Natural Antioxidants: Sources, Compounds, Mechanisms of Action ...

Natural Antioxidants: Sources, Compounds,Mechanisms of Action, and Potential ApplicationsM.S. Brewer

Abstract: While use of synthetic antioxidants (such as butylated hydroxytoluene and butylated hydroxyanisole) tomaintain the quality of ready-to-eat food products has become commonplace, consumer concern regarding their safetyhas motivated the food industry to seek natural alternatives. Phenolic antioxidants can inhibit free radical formation and/orinterrupt propagation of autoxidation. Fat-soluble vitamin E (α-tocopherol) and water-soluble vitamin C (L-ascorbicacid) are both effective in the appropriate matrix. Plant extracts, generally used for their flavoring characteristics, oftenhave strong H-donating activity thus making them extremely effective antioxidants. This antioxidant activity is mostoften due to phenolic acids (gallic, protocatechuic, caffeic, and rosmarinic acids), phenolic diterpenes (carnosol, carnosicacid, rosmanol, and rosmadial), flavonoids (quercetin, catechin, naringenin, and kaempferol), and volatile oils (eugenol,carvacrol, thymol, and menthol). Some plant pigments (anthocyanin and anthocyanidin) can chelate metals and donate Hto oxygen radicals thus slowing oxidation via 2 mechanisms. Tea and extracts of grape seeds and skins contain catechins,epicatechins, phenolic acids, proanthocyanidins, and resveratrol, all of which contribute to their antioxidative activity.The objective of this article is to provide an overview of natural antioxidants, their mechanisms of action, and potentialapplications.

IntroductionUltimately, food quality is defined in terms of consumer ac-

ceptability: taste, aroma, and appearance characteristics. The in-creasing demand for convenient foods has led to rapid growth inthe ready-to-eat product category (Hofstrand 2008). Many of thefood ingredients contain unsaturated fatty acids that are quite sus-ceptible to quality deterioration, especially under oxidative stress.For this reason, efforts to reduce oxidation have increased. Mostoften, the best strategy is the addition of antioxidants.

Synthetic phenolic antioxidants (butylated hydroxyanisole[BHA], butylated hydroxytoluene [BHT], and propyl gallate)effectively inhibit oxidation; chelating agents, such as ethylenediamine tetra acetic acid (EDTA), can bind metals reducing theircontribution to the process. Some vitamins (ascorbic acid [AA] andα-tocopherol), many herbs and spices (rosemary, thyme, oregano,sage, basil, pepper, clove, cinnamon, and nutmeg), and plant ex-tracts (tea and grapeseed) contain antioxidant components as well(Hinneburg and others 2006). Natural phenolic antioxidants, suchas synthetics, can effectively scavenge free radicals, absorb light inthe ultraviolet (UV) region (100 to 400 nm), and chelate tran-sition metals, thus stopping progressive autoxidative damage andproduction of off-odors and off-tastes.

MS 20101442 Submitted 10/22/2010, Accepted 3/8/2011. Author is with theDept. of Food Science and Human Nutrition, 202 ABL, 1302 W. PennsylvaniaAve., Univ. of Illinois, Urbana, IL 61801, U.S.A. Direct inquiries to author Brewer(E-mail: [email protected]).

Since 1994, consumers have expressed concern about the safetyof preservatives and additives in their food (Brewer and Russon1994; Brewer and Prestat 2002; Rojas and Brewer 2008b). Morethan 12 y ago, Sloan (1999) reported that one of the top 10 trendsfor the food industry to watch included the sales of natural, or-ganic, and vegetarian foods. There is a clear trend in consumerpreference for clean labeling (Hillmann 2010), for food ingre-dients and additives that are organic/natural with names that arefamiliar, and that are perceived to be healthy (Joppen 2006). In ad-dition, the call for sustainable sources and environmentally friendlyproduction is forcing the food industry to move in that direction(Berger 2009).

Defrancesco and Trestini (2008) estimated that consumers werewilling to pay a price premium (up to 70% more) for organicfresh produce (tomatoes) for their health-promoting antioxidantcontent. Of an estimated $17 billion in sales in the United States,organic foods account for only 3% of total retail food sales. Thiscategory has been growing at 7 times the rate of the averagefood category and has maintained a growth rate of more than 15%per year. However, based on the results of a recent study, Evans andothers (2010) concluded that products with physical changes, lessprocessing, with identifiable ingredients would also be perceivedto be more natural.

Consumer expectations about ingredients that may suitably belabeled as “natural” do not always coincide with current guidelines(Williams and others 2009). A clear definition can guide manufac-turers. However, the lack of consumer consensus makes it difficultfor them to understand the implications. For consumers, “natural”

c© 2011 Institute of Food Technologists®

doi: 10.1111/j.1541-4337.2011.00156.x Vol. 10, 2011 � Comprehensive Reviews in Food Science and Food Safety 221

Natural antioxidants . . .

and “clean label” are related to what they perceive an ingredientto be.

This article provides an overview of naturally occurring an-tioxidant compounds, their sources, and mechanisms of action.Various different mechanisms may contribute to oxidative pro-cesses in complex systems, such as foods. These include reactionsthat generate reactive oxygen species that target different struc-tures (lipids, proteins, and carbohydrates), and Fenton reactions,where transition metal ions play a vital role. It should be notedthat antioxidant activity of food extracts can be determined using avariety of tests (stable free radical scavengers: galvinoxyl, diphenyl-b-picrylhydrazyl [DPPH]; lipid oxidation: peroxide oxygen, con-jugated dienes, Rancimat [measurements of oxygen consumptionof a linoleic acid emulsion and oxidation induction period in lardat 100 ◦C], oxygen radical absorbance capacity [ORAC] values ),active oxygen method, iodine value (measure of the change innumber of double bonds that bind I), anisidine value (reaction ofacetic acid p-anisidine and aldehydes to produce a yellow colorthat absorbs at 350 nm), measurement of absorbance at 234 nm(conjugated dienes) and 268 nm (conjugated trienes) to assess oxi-dation in the early stages, and chromatographic methods; however,extraction procedures strongly influence the composition of theextracts and, therefore, also influence the antioxidant activity re-sults (Halliwell 1997; Schwarz and others 2001; Trojakova andothers 2001). In addition, the effect of the antioxidant compoundin a food matrix may be significantly different than the activity ofa purified extract.

Food LipidsThe fatty acids in the lipids of food tissues may be saturated or

unsaturated and may be part of the neutral triglyceride fraction(triacylglycerol) or part of the phospholipid fraction. Free fattyacids are electron-deficient at the oxygen atom of the carbonylgroup (C=O); unsaturated fatty acids are also electron-deficientat points of carbon–carbon unsaturation (C=C). These electron-deficient regions make fatty acids susceptible to attack by a vari-ety of oxidizing and high-energy agents generating free radicals(Nawar 1996). Triglycerides contain straight chains of primarily16- to 18-carbon fatty acids and minimal amounts of unsaturatedfatty acids. Phospholipids in tissue membranes contain up to 15times the amount of unsaturated fatty acids (C18:4, C20:4, C20:5,C22:5, and C22:6) found in triglycerides. They are much moresusceptible to oxidation because of the increase in the number ofpoints of carbon–carbon unsaturation (C=C) (Elmore and others1999).

OxidationWhen a hydrogen atom (H

�

) is abstracted from an unsaturatedfatty acid (R:H) forming an alkyl radical (R

�

), lipid oxidation isinitiated (see nr 1 below). Generation of this lipid radical is ther-modynamically unfavorable and is usually initiated by the presenceof other radical compounds (R

�

), singletstate oxygen (1O2), de-composition of hydroperoxides (ROOH), or pigments that act asphotoensitizers. In order to stabilize, the alkyl radical (R

�

) usuallyundergoes a shift in the position of the double bond (cis to trans)and production of a conjugated diene system. The R

�

can reactwith O2 to form a high-energy peroxyl radical (ROO

�

; see nr 2below). The peroxyl radical can then abstract a hydrogen atom(H

�

) from another unsaturated fatty acid (see nr 3 below) forminga hydroperoxide (ROOH) and a new, free alkyl radical (R

�

). Thisprocess then propagates to another fatty acid (see nr 4 below; Srini-vasan and others 2008). Lipid hydroperoxides (ROOH) are the

Table 1–Flavors and aromas associated with volatile compounds resultingfrom lipid oxidation.

Compound Flavors and aromas

Butanoic acid RancidPropanoic acid Pungent, rancid, soyPentanal Pungent, maltHexanal Green, grassy, tallowyHeptanal Green, oily, rancidOctanal Sweet, fatty, soapyNonanal Tallowy, waxyDecanal Rancid, burntDecanal Soapy, tallowy2-Nonenal Paper2-Hexenal RancidNona-2(E)-enal Tallowy, fattyE-2-Hexenal Green, fat, rancidE-2-Octenal Fatty, nutty, greenE-2-Decenal Green, pungent,E,E-Deca-2, 4-dienal Fatty, fried potato, greenE,E-Nona-2, 4-dienal Green, grassy, fatty2-Propanone Livery3-Hydroxy-2-butanone Rancid, beany, grassy2,3-Octanedione Oxidized fat or oilNonenone Pungent2-Heptanone SoapyDimethyl disulfide Onion, cabbage, putridDimethyl trisulfide Sulfur, fish, cabbageMethanethiol Garlic, sulfur

Kerler and Grosch (1996), Yong and others (2000), Ahn and others (2002, 2007), Jensen and others(2002), Jo and others (2003), Mahrour and others (2003), Nam and Ahn (2003), Nam and others(2003), Acree and Arn (2004), Rochat and Chaintreau (2005), Obana and others (2006), and Yanceyand others (2006).

primary products of lipid oxidation. They are tasteless and odor-less; however, in the presence of heat, metal ions, and/or light, theycan decompose to compounds that contribute off-odors and off-tastes. Alkoxy radicals (RO

�

) can also abstract H�

from unsaturatedfatty acids continuing the chain reaction (see nr 5 below; Decker2002; Srinivasan and others 2008). Hydroxyl radicals (

�

OH) canreact with conjugated systems continuing the oxidation process.This chain reaction terminates when 2 radical species combine toform a nonradical species (see nr 6 below). Antioxidants (A:H)inhibit the chain reaction by donating hydrogen atoms (H

�

) toradicals (see nr 7 below). The antioxidant free radical may thenform a stable peroxy-antioxidant compound (see nr 8 below).

(1) R:H + O::O + Initiator → R�

+ HOO�

(2) R�

+ O::O → ROO�

(3) ROO�

+ R:H → ROOH + R�

(4) RO:OH → RO�

+ HO�

(5) R::R +�

OH → R:R-O�

(6) R�

+ R� → R:R

(7) R�

+ ROO�→ ROOR

(8) ROO�

+ ROO� → ROOR + O2

(9) ROO�

+ AH → ROOH + A�

(10) ROO�

+ A� → ROOA.

Ultimately, oxidation depends on the addition of oxygen to acompound; however, the energy level of the oxygen has a sig-nificant impact on the ease of the oxidation reaction. Singletstate oxygen (1O2) has spin-coupled electrons and is a nonrad-ical, high-energy species (Decker 2002; Min and Boff 2002). It iselectrophilic and can react with other electron-rich, nonradical,singlet state compounds containing double bonds (C=C, C=O).However, oxygen in its lowest energy state, triplet state oxygen(3O2), has 2 unpaired, parallel spin electrons. It is very reactive(primarily with radical species). Most food components, such ascarbohydrates and proteins, are nonradical (singlet state) and arerelatively unreactive with triplet state oxygen (3O2); however, they

222 Comprehensive Reviews in Food Science and Food Safety � Vol. 10, 2011 c© 2011 Institute of Food Technologists®


are reactive with singlet state oxygen (1O2) that can be generatedin response to temperature change, reduction of activation en-ergy (presence of transition metals), exposure to UV light, andphysical damage to tissues. Singlet oxygen and free radicals cancause biological damage to macromolecules and membrane con-stituents. The presence of natural antioxidants may help controlthese degradative reactions.

Oxidation of unsaturated fatty acids can produce a variety ofaldehydes, alkanals, alkenes, and alkanes; many of which con-tribute off-odors that are perceptible at very low concentrations.Odor detection thresholds for pentanal, hexanal, and heptanal,compounds typically generated from the breakdown of oxidizedlinoleic acid have been reported to be <34, <38, and 62 ppb, re-spectively, in a gelatin model system (Vega and Brewer 1995). Theodors of a variety of oxidation-generated compounds are shownin Table 1.

AntioxidantsAntioxidants are compounds or systems that delay autoxidation

by inhibiting formation of free radicals or by interrupting propaga-tion of the free radical by one (or more) of several mechanisms: (1)scavenging species that initiate peroxidation, (2) chelating metalions such that they are unable to generate reactive species or de-compose lipid peroxides, (3) quenching

�

O2− preventing forma-

tion of peroxides, (4) breaking the autoxidative chain reaction,and/or (5) reducing localized O2 concentrations (Nawar 1996).Chain-breaking antioxidants differ in their antioxidative effec-tiveness depending on their chemical characteristics and physicallocation within a food (proximity to membrane phospholipids,emulsion interfaces, or in the aqueous phase). The chemical po-tency of an antioxidant and solubility in oil influence its acces-sibility to peroxy radicals especially in membrane, micellar andemulsion systems, and the amphiphilic character required for ef-fectiveness in these systems (Wanatabe and others 2010).

Antioxidant effectiveness is related to activation energy, rateconstants, oxidation–reduction potential, ease with which the an-tioxidant is lost or destroyed (volatility and heat susceptibility),and antioxidant solubility (Nawar 1996). In addition, inhibitorand chain propagation reactions are both exothermic. As theA:H and R:H bond dissociation energies increase, the activationincreases and the antioxidant efficiency decreases. Conversely, asthese bond energies decrease, the antioxidant efficiency increases.

The most effective antioxidants are those that interrupt the freeradical chain reaction. Usually containing aromatic or phenolicrings, these antioxidants donate H

�

to the free radicals formedduring oxidation becoming a radical themselves (see step nr 7).These radical intermediates are stabilized by the resonance delo-calization of the electron within the aromatic ring and formation ofquinone structures (Nawar 1996). In addition, many of the phe-nolics lack positions suitable for molecular oxygen attack. Bothsynthetic antioxidants (BHA, BHT, and propyl gallate) and naturalbotanicals contain phenolics (flavonoids) function in this manner.Botanical extracts with antioxidant activity generally quench freeradical oxygen with phenolic compounds as well.

Because bivalent transition metal ions, Fe2+ in particular, cancatalyze oxidative processes, leading to formation of hydroxyl rad-icals, and can decompose hydroperoxides via Fenton reactions,chelating these metals can effectively reduce oxidation (Halliwelland others 1987). Food materials containing significant amountsof these transition metals (red meat) can be particularly susceptibleto metal-catalyzed reactions.

Table 2–Total ORAC values (μm TE/100 g; Prior and others 2003) ofselected herbs and spices, berries, roots, and teas.

Food Total ORAC SEM

Basil (fresh) 4805 225Marjoram (fresh) 27297 1306Oregano (fresh) 13970 545Sage (fresh) 32004 1548Savory (fresh) 9465 436Basil (dried) 61063 2280Cinnamon (ground) 131420 13867Clove (ground) 290283 3292Ginger (ground) 39041 1835Nutmeg (ground) 69640 6859Oregano (dried) 175295 7683Pepper, black 34053 289Rosemary (dried) 165280 1391Sage (ground) 119929 20305Thyme (fresh) 27426 1251Thyme (dried) 157380 1629Turmeric (ground) 127068 11181Grapes (red, raw) 1837 248Raspberries (raw) 5065 205Garlic (raw) 5708 475Ginger root (raw) 14840 530Onions, red (raw) 1521 69Tea brewed 1128 −Tea, green, brewed 1253 −The oxygen radical absorbance capacity (ORAC) method is based on the inhibition of theperoxyl-radical-induced oxidation initiated by thermal decomposition of azo compounds. Prior andothers (2003) used 2,2′ -azo bis (2 amidino propane) dihydrochloride (AAPH) as the azo generator,incubated at 37 ◦C for 30 min with fluorescein (14 μm) as a fluorescent detector.Source: USDA (2010).

Natural AntioxidantsFood tissues, because they are (or were) living, are under con-

stant oxidative stress from free radicals, reactive oxygen species,and prooxidants generated both exogenously (heat and light) andendogenously (H2O2 and transition metals). For this reason, manyof these tissues have developed antioxidant systems to control freeradicals, lipid oxidation catalysts, oxidation intermediates, and sec-ondary breakdown products (Nakatani 2003; Agati and others2007; Brown and Kelly 2007; Chen 2008; Iacopini and others2008). These antioxidant compounds include flavonoids, pheno-lic acids, carotenoids, and tocopherols that can inhibit Fe3+/AA-induced oxidation, scavenge free radicals, and act as reductants(Khanduja 2003; Ozsoy and others 2009).

Spices and herbs, used in foods for their flavor and in medicinalmixtures for their physiological effects, often contain high con-centrations of phenolic compounds that have strong H-donatingactivity (Lugasi and others 1995; Muchuweti and others 2007).

Table 3–Content of redox-active compounds (antioxidants) of selectedfoods (mmol/100 g).

Redox-active compoundFood content (mmol/100 g)

Cloves, ground 125.5Oregano leaf, dried 40.3Ginger, ground 21.6Cinnamon, ground 17.7Turmeric powder 15.7Basil leaf, dried 12.3Curry powder 10.0Paprika 8.6Pepper, black 4.4Raspberries 2.3Wine, red 2.1Cherries, sour 1.8

Sources: McCormick Institute Antioxidant Comparison (2009) and Halvorsen and others (2006).

c© 2011 Institute of Food Technologists® Vol. 10, 2011 � Comprehensive Reviews in Food Science and Food Safety 223


COOH

OH

OH

HO

OH

OHO

HO

OH

OHO

Gallic acid Protocatechuic acid p-Coumaric acid

OH

HO

OHO

OH

HO

O

HO

O

O

OH

OH

Caffeic acid Rosmarinic acid

Figure 1–Antioxidative phenolic acids (gallic,protochatechuic, p-coumaric acid, caffeic, androsmarinic) found in plant extracts. Allstructures generated using ChemBioOffice(2008).

Many also have high ORAC values (Table 2 and 3). Some plant-derived compounds (carnosol, rosmanol, rosmariquinone, androsmaridiphenol) are better antioxidants than BHA (Richheimerand others 1996; Carvalho and others 2005).

The major antioxidative plant phenolics can be divided into4 general groups: phenolic acids (gallic, protochatechuic, caffeic,and rosmarinic acids; Figure 1), phenolic diterpenes (carnosoland carnosic acid; Figure 2), flavonoids (quercetin and catechin;Figure 3), and volatile oils (eugenol, carvacrol, thymol, and men-thol; Figure 4; Shan and others 2005). Phenolic acids generallyact as antioxidants by trapping free radicals; flavonoids can scav-enge free radicals and chelate metals as well (Engeseth and Geldof2001).

The common characteristic of the flavonoids (flavones,flavonols, flavanols, and flavanones) is the basic 15-carbon flavanstructure (C6C3C6; Figure 5). These carbon atoms are arrangedin 3 rings (A, B, and C). Classes of flavonoids differ in the level ofsaturation of the C ring. Individual compounds within a class dif-

fer in the substitution pattern of the A and B rings that influencethe phenoxyl radical stability and the antioxidant properties of thesubstances (Wojdyło and others 2007).

The free radical-scavenging potential of natural polyphenoliccompounds appears to depend on the pattern (both number andlocation) of free −OH groups on the flavonoid skeleton (Lupeaand others 2008). The B-ring substitution pattern is especiallyimportant to free radical-scavenging ability of flavonols. Study-ing the ability of 4 flavonols substituted at different points on theB-ring (galangin, kaempferol, quercetin, and myricetin) to quenchthe intrinsic fluorescence of bovine serum albumen, Xiao andothers (2008) found that myricetin > quercetin > kaempferol >

galangin. Authors interpret these findings as indicating that hy-drogen bond force plays an important role.

Flavonoids with multiple hydroxyl groups are more effectiveantioxidants than those with only one. The presence of the ortho-3,4-dihydroxy structure increases the antioxidative activity (Geldofand Engeseth 2002). Flavonoids can dampen transition metal



CH3H3C

CH3

OH

CH3 CH3

Diterpene structure

OH

OH

O

H

O

OH

HO

OH

COOH

Carnosol Carnosic acid

OCH2CH3

CH3H3C

HO

OH

CH3

CH3

O

CHO

OH

HO

O

HO

O

O

OH

OH

Rosmanol Rosmarinic acid

Figure 2–Antioxidative phenolic diterpenes(carnosol, carnosic acid, rosmanol, androsmarinic acid) found in plants.

enhancement of oxidation by donating a H�

to them, renderingthem less proxidative. In addition, flavones and some flavanones(naringenin) can preferentially bind metals at the 5-hydroxyl and4-oxo groups (Fernandez and others 2002).

Brown and Kelly (2007) evaluated the antioxidative activity ofstructurally related (poly)phenols, anthocyan(id)ins, and phenolicacids at physiologically relevant concentrations (100 to 1000 nM)using a Cu2+-mediated low-density lipoprotein oxidation model.(Poly)phenols with an ortho-dihydroxy substituted arrange-ment (cyanidin-3-glucoside, cyanidin, and protocatechuic acid)were the most effective, while trihydroxy-substituted compounds(gallic acid) had only intermediate efficacy. This was explained, inpart, by their ability to chelate Cu2+ ions. It seems likely that thesteric relationship of these −OH groups and their arrangement onthe ring(s) both play a role in the ability of the substance to chelatemetal ions. However, differences in lipid/hydrophilic phase parti-

tioning and in H-donating abilities were also hypothesized to havecontributed to the structure-activity relationships.

Alamed and others (2009) reported that the order of free radical-scavenging activity of a group of polar compounds was ferulicacid > coumaric acid > propyl gallate > gallic acid > AA; thefree radical-scavenging activity of a group of nonpolar compoundswas rosmarinic acid > BHT, tert-butylhydroquinone (TBHQ) >

α-tocopherol. Only propyl gallate, TBHQ, gallic acid, androsmarinic acid inhibited lipid oxidation in an oil-in-water emul-sion that may reflect the ability of these compounds to orient atthe interface of the oil droplet in the emulsion.

Evaluating the antioxidative activity of hydroxycinnamic acidswith similar structures (caffeic, chlorogenic, o-coumaric, andferulic acids) in a fish muscle system, Medina and others (2007)found that the capacity of these compounds to donate electrons(bond dissociation energies) appeared to play the most significant



O

OH

HO

OH

OH

OH

OHO

OH

OH

OH

OH

O

Epicatechin Quercetin (flavanol)

O

OH

HO

HO

O

OH

OH

O

HO

HO

OH

O

O

OH

OH

OH

O

OH

OH

OH

HO

HO

Epicatechin gallate Epigallocatechin gallate

Rutin

O O

OH

HO

OH

OHO

O

O

HO

HO

OH O O

OH

OH

HO

Figure 3–Antioxidative flavonoids (epicatechin, quercetin, epicatechin gallate, epigallocatechin gallate, and rutin) found in plant extracts.



OH3C

HO

HO

O

O

Eugenol Carvacrol Safrole

OH OH

O

O

H2C

O

H3C

Thymol Menthol Myristicin

O

CH3

H3C

CH3

OH

CH3

H3C CH3 O

1,8-Cineol edyhedlamanniC enemyC-p loenipreT -

N

O

O

O

Piperine

Figure 4–Antioxidant volatile oils (eugenol, carvacrol, safrole, thymol, menthol, 1,8-cineole, α-terpineol, p-cymene, cinnamaldehyde, myristicin, andpiperine) found in plant extracts.

role in delaying rancidity, while the ability to chelate metals andthe distribution between oily and aqueous phases were not cor-related with inhibitory activities. The latter finding may reflectthe type of matrix, fish muscle, in which the oxidative activitywas studied. Caffeic acid was the most effective of this antioxidantgroup (similar to propyl gallate).

Potapovich and Kostyuk (2003) reported that, of a variety offlavonoids (rutin, dihydroquercetin, quercetin, epigallocatechingallate, and epicatechin gallate), the catechins were mosteffective in inhibiting microsomal lipid peroxidation. All wereable to chelate Fe2+, Fe3+, and Cu2+ and were effective

�

O2−

scavengers to varying degrees. Authors speculate that the



7

6

5

4

9

8

3

2

1

A

B

Basic C6, C3, C6 structure Chalcone

O

A C

B

O

HO

OH

O

A C

B

O

OH

O

A C

B

O

Flavone Flavonol Flavanone

7

6

5

3

O 5'

4'

3'

+

R1

R2

R3

R4

R5

R6

R7

O

OO

O

O

HO

OH

OH

OH

OH

HO

OH

OH

HO

HO

Anthocyanin (R2= -OH, R4= -OH Anthocyanidin-3,5-glucoside or H, R5 and R7= -OH or –OCH3

Figure 5–Flavonoid structure and flavonoids (flavanones: chalcone, flavone, flavanol, and flavanones; and flavans: anthocyanin andanthocyanidin-3,5-glycoside) found in plant extracts.

relative ability to scavenge�

O2− may be responsible for the relative

antioxidative difference among these compounds.Many of the antioxidative flavonoid compounds are naturally

occurring pigments. It appears that chloroplast-located flavonoidsperform a photo-protective role against

�

O2− in plants (Agati and

others 2007). Anthocyanins are the glycosides of polyhydroxy orpolymethoxy derivatives of the flavylium cation. Hydrolysis ofthe sugar moiety yields an aglycone, anthocyanindin (Figure 5).Anthocyanins and anthocyanindins exhibit visual color becauseof the extreme mobility of the electrons within the molecularstructure (double bonds) in response to light in the visible spectrum(approximately 400 to 700 nm). The pigments are quite water-

soluble and 4 −OH groups are bound to the aromatic rings. pHhas a significant effect on anthocyanin pigments. These −OHgroups can give up H+ (in a basic solution) or H

�

to an oxidizinglipid (ROO

�

).Proanthocyanidins also contain multiple −OH groups that can

donate hydrogen, quench�

O2−, and chelate metals (Shahidi and

Wanasundara 1992; Fukumoto and Mazza 2000). Free radical-scavenging ability increases as the number of phenolic −OHgroups increases (Kondo and others 2001).

Some phenols can polymerize into polyphenols that can bindminerals. Proanthocyanidins often occur as oligomers or poly-mers of monomeric flavonoids, polyhydroxy flavan-3-ols such as



HO

CH3

CH3

O

CH3

CH3

H

H

H3C

CH3

CH2

CH2

HO

CH3

H3C O

CH3

CH3

H2C

H2C

H3C

H

H

Alpha tocopherol Gamma tocopherol

HC

CC

C

O

O

CH

OHOH

CH3

OH

OH O

O

OH

OH

HCOH

CH2O C (CH2)14 CH3

O

Ascorbic acid Ascorbyl palmitate

OH

OH

HO

O O

OHHO

OH

Propyl gallate Resveratrol

Figure 6–Natural antioxidants (alpha- and gamma-tocopherol, ascorbic acid, ascorbyl palmitate, propyl gallate, and resveratrol).

[+]-catechin and [−]-epicatechin (Dixon and others 2005;Figure 3 and 5). The polymeric procyanidins are better antiox-idants than the corresponding monomers, catechin, and epicat-echin (Ursini and others 2001). Catechin and epicatechin cancombine to form esters, such as catechin/epicatechin gallate, orbond with sugars and proteins to yield glycosides and polyphe-nolic proteins. Glycosylation of flavonoids at the 3 −OH groupusually decreases the antioxidative activity due to the reduction ofthe number of phenolic groups (quercetin/rutin; Figure 3).

Proanthocyanidins with demonstrated antioxidant activity andpotential biologically therapeutic effects occur in fruits (apples and

cherries), some berries (rosehips, raspberries, blackberries, andstrawberries), as well as in the leaves (tea), seeds (grape, sorghum,soy, and cocoa bean), and bark of many plants (Dixon and others2005; Buricova and Reblova 2008; Bak and others 2010).

α-Tocopherolα-Tocopherol (vitamin E) is a fat-soluble carotenoid whose

antioxidative capacity has been studied extensively (Figure 6).α-Tocopherol is the major vitamin E compound in plant leaveswhere it is located in the chloroplast envelope and thylakoid mem-branes in proximity to phospholipids (Onibi and others 2000). It



deactivates photosynthesis-derived reactive oxygen species (es-pecially

�

O2−) and prevents the propagation of lipid peroxida-

tion by scavenging lipid peroxyl radicals in thylakoid membranes(Munne-Bosch 2005).

Trolox is a water-soluble derivative of vitamin E. Structurallyrelated lipid-soluble antioxidants that differ in the number ofmethyl groups (δ-tocopherol compared with α-tocopherol) havedifferent free radical-scavenging activities and different surfaceactivities (Figure 6; Chaiyasit and others 2005). Giuffrida andothers (2007) evaluated the ability of α-tocopherol, δ-tocopherol,ascorbyl palmitate, and propyl gallate (300 mg/kg; Figure 6) to pre-vent oxidation in sunflower oil and high-oleic sunflower oil, bothrich in di-unsaturated fatty acids, and in partially hydrogenatedpalm oil containing monounsaturated fatty acids. δ-Tocopherolwas the most effective antioxidant in sunflower oil, and propylgallate was the most effective in the more saturated oils. Yeumand others (2009) reported synergistic effects between AA andα-tocopherol in protecting an in vitro biological model system.It may be that AA regenerates α-tocopherol after α-tocopheroldonates a H

�

to an oxidizing lipid.α-Tocopherol can also inhibit oxidation of protein. Estevez and

Heinonen (2010) demonstrated that α-tocopherol reduced for-mation of α-aminoadipic and γ -glutamic semialdehydes from ox-idized myofibrillar proteins.

In general, vitamin E added to water-based food systems us-ing an oil carrier targets the neutral lipid fraction (triacylglyc-erols) rather than the polar lipid fraction (phospholipids) and isnot an effective antioxidant. However, δ-tocopherol added usinga polar carrier can be incorporated into the phospholipid fractionand is an effective antioxidant (Wills and others 2007). In a lardmodel system, the antioxidative activity of the tocopherols is tem-perature dependent (Reblova 2006). At 80 ◦C, the antioxidativeactivity of δ-tocopherol is about twice that of α-tocopherol; how-ever, it decreases as temperature increases. Antioxidative activity ofα-tocopherol decreases above 110 ◦C, and both lose their activityabove 150 ◦C.

Dietary supplementation of α-tocopherol increases incorpo-ration of the antioxidant into the phospholipid membrane re-gion where the polyunsaturated fatty acids are located. Includingα-tocopherol in livestock diets has been shown to have signifi-cant effects on the antioxidative activities of their tissues and thestability of meat derived from them (Formanek and others 2001;Swigert and others 2004; Guo and others 2006; Boler and others2009; Lahucky and others 2010).

Ascorbic acidAA has 4 −OH groups that can donate hydrogen to an oxi-

dizing system (Figure 6). Because the −OH groups (2 pairs of 2)are on adjacent carbon atoms, AA is able to chelate metal ions(Fe++). It also scavenges free radicals, quenches

�

O2−, and acts as

a reducing agent. At high levels (>1000 mg/kg), AA shifts thebalance between ferrous (Fe2+) and ferric iron (Fe3+), acts as anoxygen scavenger, and inhibits oxidation. However, at low levels(<100 mg/kg), it can catalyze oxidation (in muscle tissue; Ahnand others 2007; Yetella and Min 2008).

Environmental conditions and the presence of other compoundsin the system can alter the antioxidative capacity of AA. Allam andMohamed (2002) reported that, using the induction period forthe oxidation of sunflower oil as a measure of antioxidant activityafter heating (180 ◦C), ascorbyl palmitate was less thermally stablethan mixed tocopherols, propyl gallate, BHT, or BHA. This maybe a function of the water solubility of AA.

HerbsA number of spices and herbs contain compounds that can be

removed and added to food systems to prevent oxidation (Lee andShibamoto 2002; Ahn and others 2007; Rojas and Brewer 2007,2008a; Sasse and others 2009). Antioxidant (and flavor) compo-nents of herbs and spices may be removed/concentrated as extracts,essential oils, or resins. Extracts are soluble fractions that can beremoved from plant materials by solubilizing the component(s) ofinterest in an aqueous, lipid, alcohol, solvent, or supercritical CO2

phase then removing it. Essential oils are the volatile oils and oftencontain isoprenoid compounds. Chemically, essential oils are ex-tremely complex mixtures containing compounds of every majorfunctional group class. Essential oils are isolated by steam distilla-tion, extraction (solvent or CO2), or mechanical expression fromthe plant material. Plants also contain resins that are nonvolatile,high molecular weight, amorphous solids, or semisolids that flowwhen subjected to heat or stress. They are typically light yellowto dark brown in color, tasteless, odorless or faintly aromatic, andtranslucent or transparent. Most resins are bicyclic terpenes (alpha-and beta-pinene, delta-3 carene, and sabinene), monocyclic ter-penes (limonene and terpinolene), and tricyclic sesquiterpenes(longifolene, caryophyllene, and delta-cadinene). They are solu-ble in most organic solvents but not in water. Resins may containsmall amounts of volatile phenolic compounds.

Extracts of many members of the Labiatae (Lamiaceae) fam-ily (oregano, marjoram, savory, sage, rosemary, thyme, and basil),which are antioxidative, have a high total phenol content (Chenand others 2007). They do not necessarily have a high free radical-scavenging ability but appear to contain components that func-tion by at least 2 different antioxidative mechanisms (Madsen andothers 1996). Dorman and others (2003) observed that, whilethese antioxidant characteristics are not entirely related to the totalphenolic contents, they do appear to be strongly dependent on ros-marinic acid, the major phenolic component present. Rosmarinicacid has vicinal −OH groups on each of 2 aromatic rings, whilecarnosic acid, carnosol, and rosmanol each have vicinal −OHgroups on only 1 aromatic ring (Figure 3). A number of herbs(chamomile, rosehip, hawthorn, and lemon verbena) can enhancethe activity of antioxidative enzymes such as superoxide dismutaseand catalase in a dose-dependent manner and have been shown toenhance cell viability and provide protective effects against oxida-tive stress induced by hydrogen peroxide (in lung fibroblasts; Yooand others 2008).

RosemaryChen and others (2007) reported that, of several herbs (Psidium

guajava L., Camellia sinensis [Gamma Amino Butyric Acid tea], T.sinensis Roem., and Rosemarinus officinalis L.), the aqueous extractof rosemary contained the highest concentration of phenolic sub-stances (185 mg/g; Folin–Ciocalteau) and total flavonoids (141mg/g). This aqueous extract inhibited UVB-induced (100 to 400nm) oxidation of an erythrocyte ghost system (in vivo model sys-tem) at a relatively low concentration (100 μg/mL; Chen andothers 2007). At 100 mcg/mL, rosemary extract was able to scav-enge 39% of the DPPH radicals (0.2 μm); at 500 mcg/mL, itscavenged 55%. Rosemary extract (100 mcg/mL) inhibited lipo-some (egg lecithin with Fe3+/AA/H2O2) oxidation by 98%.

The most active antioxidative constituents of rosemary (R.officinalis) are phenolic diterpenes (carnosic, carnosol, rosmanol,rosmadial, 12-methoxycarnosic acid, epi-, and iso-rosmanol) andphenolic acids (rosmarinic and caffeic) (Table 4; Figure 1 and 2;Frankel 1991; Frankel and others 1996; Richheimer and others



Tabl

e4–

Sele

cted

anti

oxid

ant

com

poun

dsid

enti

fied

inse

lect

edhe

rbs.

Phen

olic

dite

rpen

esPh

enol

icac

ids

Vol

atile

sPh

enyl

prop

anoi

dsSi

mpl

eRo

s-Ep

i-,is

o-Ro

s-Ro

smar

i-Ca

rnos

icCa

rn-

Rosm

ar-

phen

olic

Caff

eic

1,8-

α-

α,β

Carv

p-Fl

avo-

man

olro

sm

anol

mad

ial

diph

enol

acid

osol

inic

acid

acid

sac

ids

Cine

ole

Thuj

ene

pine

neTh

ymol

Euge

nol

acro

lCy

men

eno

ids∗

Rose

mar

y∗X

XX

XX

XX

XX

XX

XO

rega

no∗

XX

XX

XX

XX

Sage

∗X

XX

XX

XX

XTh

yme∗

XX

XX

XX

XX

Mar

jora

m∗

XX

XX

Sum

mer

savo

ry∗

XX

XX

XX

X

Bay

Leaf

XX

XX

XBa

sil∗

XX

XX

XX

XX

X∗ La

mia

ceae

fam

ily.

Nak

atan

iand

Inat

ani(

1981

),A

roum

aan

dot

hers

(199

2),C

uvel

iera

ndot

hers

(199

4),D

orm

anan

dot

hers

(200

0,20

03),

Ahn

and

othe

rs(2

002,

2007

),A

okia

ndW

ada

(200

3),D

orm

anan

dot

hers

(200

3),T

hors

enan

dH

ildeb

rand

t(20

03),

Lee

and

othe

rs(2

005)

,Boz

inan

dot

hers

(200

6),

Carr

illo

and

Tena

(200

6),Y

anis

hiev

aan

dot

hers

(200

6),H

atzi

dim

itrio

uaan

dot

hers

(200

7),B

itara

ndot

hers

(200

8),a

ndH

erna

ndez

-Her

nand

ezan

dot

hers

(200

9).

1996; Nakatani 2003; Thorsen and Hildebrandt 2003; Carvalhoand others 2005). Carnosic acid has several times the antioxida-tive activity as BHT and BHA (Richheimer and others 1996).The synthetic phenolic antioxidants, BHA and BHT, each havea single aromatic ring with 1 −OH group capable of donatingH

�

. While carnosic acid also has a single aromatic ring, it has2 −OH groups that can serve as H

�

donors. In addition, vicinal−OH groups can chelate prooxidative metals thereby preventingoxidation via 2 mechanisms. Hra and others (2000) reported that,in sunflower oil, rosemary extract exhibited antioxidant activitysuperior to α-tocopherol. The polyphenol, rosmarinic acid has2 aromatic rings, each with 2 −OH groups that are capable ofdonating H

�

and chelating metals. Adding α-tocopherol to rose-mary can have either an antagonistic effect (Hra and others 2000)or a synergistic effect (Aoki and Wada 2003). This may indicatethat there are components in rosemary, other than rosmarinic acid,which make substantial contributions to the antioxidative capacityof the extract. It may also be a function of the solubility of therosemary fractions used compared to that of α-tocopherol withrespect to the food system to which it being added.

In lipid-based systems, carnosic acid and carnosol effectivelychelate iron and scavenge peroxyl radical (Arouma and others1992). However, free radical-scavenging activity ability does varyamong the different compounds: 1,8-cineole = 62.5%, β-pinene =46.2%, and α-pinene = 42.7% found in rosemary essential oil(Wang and others 2008). The ethanol extract of rosemary hashigher antioxidative activity than do the individual phenolic com-pounds (carnosic acid, carnosol, 1,8-cineole, α-pinene, camphor,camphene, and β-pinene) separately (Wang and others 2008;Hernandez-Hernandez and others 2009). Solvents of medium po-larity extract higher concentrations of carnosic acid from rosemaryand sage than do solvents of higher or lower polarity (Trojakova andothers 2001). In addition, different varieties of rosemary, grownin different regions under different conditions may vary in thecontent of these phenolic compounds.

OreganoWater/ethanol, dichloromethane, and ethanol extracts of

oregano (Origanum vulgare L.) also contain high concentrationsof phenols, primarily rosmarinic acid, as well as phenolic car-boxylic acids and glycosides that are both antioxidative and ef-fective superoxide anion radical scavengers (Kim and Cho 2001;Bendini and others 2002; Nakatani 2003; Hernandez-Hernandezand others 2009; Table 3 and 4). Oregano has a high total phe-nolic compound concentration (15.8 mg gallic acid equivalent[GAE]/g) and antioxidant activity. Using the reducing power as-say, radical-scavenging assay, and the beta-carotene linoleic acidmodel system, Muchuweti and others (2007) determined thatoregano had an antioxidant activity of 58.3% exceeded only bycinnamon (61.8%). Using hexanal as an indicator, Stashenko andothers (2002) demonstrated that the essential oils of oregano androsemary were both more effective at inhibiting Fe2+-induced oxi-dation of linoleic acid in a sunflower oil model system than vitaminE, Trolox, or BHA. This fraction contained unglycosylated andglycosylated flavanones as well as dihydroflavonols, all of whichhave antioxidative activity.

MarjoramOf a number of herbs and spices (bay leaves, rosemary, sage,

marjoram, oregano, cinnamon, parsley, sweet basil, and mint),marjoram (Origanum majorana L.) has the highest proportion ofsimple phenolic compounds (96%; Muchuweti and others 2007).



Marjoram essential oil also contains a significant amount of bothrosmarinic acid and carnosol (Table 4; Figure 1 and 2). The es-sential oil can scavenge hydroxyl radicals (OH

�

). It has antiradicalactivity exceeding that of the phenolic component thymol. In alinoleic acid model system, at 5 mg/mL, marjoram has a radical-scavenging activity of 92%, inhibits conjugated diene formationby 50%, and formation of secondary oxidation products by 80%(Schmidt and others 2008).

Jun and others (2001) isolated a component (T3b) from marjo-ram, which is likely a phenolic substance, that is a better superoxideanion radical scavenger than α-tocopherol, BHA, BHT, AA, epi-gallocatechin gallate, quercetin, or epicatechin (Figure 3). Theinhibitory mechanism of T3b appears to depend on the actionof superoxide dismutase, an endogenous enzyme that destroys su-peroxide anion by converting it to H2O2. These authors reportedthat the methanol extract of marjoram exhibited strong superoxideanion radical-scavenging ability (85.5%).

Marjoram essential oil is also rich in terpinen-4-ol, cis-sabinenehydrate, p-cymene, and γ -terpinene (Vera and Chane-Ming 1999;Edris and others 2003; Novak and others 2003). The bicyclicmonoterpenes, cis-sabinene hydrate and cis-sabinene hydrate ac-etate, appear to be responsible for the flavor of marjoram (Richterand Schellenberg 2007). To the extent that these aromatic com-pounds can be separated from marjoram, this herb could be addedto foods without adding unwanted flavors.

SageThe polar extracts of sage (Salvia officinalis) have strong radical-

scavenging ability and superoxide anion radical-inhibiting ability(Orhan and others 2007). The antioxidative activity of sage oilcompounds, due primarily to the presence of compounds withvicinal −OH groups, is correlated with the oxygenated diter-pene and sesquiterpene concentrations (Papageorgiou and oth-ers 2008). Sage contains some of the same antioxidant phenolicditerpene compounds found in rosemary such as carnosol, ros-manol, and rosmadial, in addition to some not found in rosemary(methyl carnosate, 9-ethylrosmanol ether, epirosmanol, isoros-manol, and galdosol) (Table 4; Figure 1 and 2; Cuvelier and others1994; Miura and others 2002; Pizzale and others 2002; Nakatani2003).

In model systems, the polar extracts of the Salvia species exhibitexcellent antioxidant activities compared to BHT (Tepe and others2006). However, adding sage (0.05%) to raw pork is a less effectiveantioxidant than feeding α-tocopherol (1000 mg/kg feed) to pigsprior to slaughter in terms of preventing oxidation in cookedpork patties (McCarthy and others 2001). This suggests that thereis a component of the polar extract that either locates in thephospholipid membrane, chelates, or reduces free iron or affectsendogenous oxidative systems.

ThymeThymus vulgaris, T. mastichina, T. caespititius, and T. camphorate all

have antioxidative activities comparable to those of α-tocopheroland BHT (Miguel and others 2004). Thyme essential oil exhibitsvery strong free radical-scavenging ability and inhibits lipid oxi-dation induced by both Fe2+/ascorbate and Fe2+/H2O2 (Bozinand others 2006). In terms of antioxidative activity, thyme oil >

thymol > carvacrol > γ -terpinene > myrcene > linalool > p-cymene > limonene > 1,8-cineole > α-pinene (Youdim andothers 2002). Carvacrol and thymol each have 1 aromatic ring and1 −OH group, 1-terpineol has 1 −OH group, while p-cymenehas 1 aromatic group. The presence of aromatic groups and the

number of −OH groups appears to coincide with the antioxidantpotential of these compounds.

Using an aldehyde/carboxylic acid assay, Lee and others (2005)demonstrated that carvacrol and thymol (5 ppm) can inhibit oxida-tion almost completely for 30 d. The primary aroma compoundsin thyme include 1,8-cineole, thymol, carvacrol, and α-terpineol(Table 4; Figure 4; Lee and others 2005). Given that thymol isthe most effective antioxidative component and also one of theprimary aroma compounds in thyme, using extracts of this herbwould likely impart unwanted flavors to foods to which they areadded unless other antioxidative but nonaromatic components canbe separated from the extract.

BasilIn basil, a significant correlation exists between the total phe-

nolic content and antioxidant activity (Juliani and Simon 2002).Purple basil (Ocimum basilicum) extracts have a higher total phe-nolic acid content and greater antioxidant activity than do greenbasil extracts. The essential oil contains <18% eugenol (Figure 4)as a percentage of the total volatiles; however, it is correlated withantioxidant activity. However, the low contribution of the essentialoil to the total antioxidant activity (0.05% to 5.9%) suggests thatthe antioxidant activity of these plants is not due to the presence ofthe essential oils as such, but to other phenolic compounds in greenbasil and to anthocyanins in purple basil (Juliani and Simon 2002).The aqueous extract of basil is a concentration-dependent super-oxide and hydroxyl radical scavenger (Padurar and others 2008).The antioxidant activity of this extract has been attributed to itspolar phenolic compounds. The total phenolic content of waterand ethanol extracts of basil (GAE) was reported to be equivalent.Hinneburg and others (2006) reported that hydrodistilled extractsfrom basil and laurel had the highest antioxidant activities of sev-eral herbs (basil, laurel, parsley, juniper, aniseed, fennel, cumin,cardamom, and ginger) but not the greatest iron chelation ability.In a linoleic acid peroxidation assay, basil extract was as effectiveas Trolox. Basil also exhibited significant iron-reducing capacity.

Rosmarinic acid has been identified as the primary pheno-lic compound in basil leaves and stems (Lee and Scagel 2009).Linalool, epi-α-cadinol, and α-bergamotene (7.4% to 9.2%) andγ -cadinene have been identified as the most common compoundsin basil essential oil (Hussain and others 2008). Basil essential oilstrongly inhibits lipid peroxidation whether induced by Fe2+ ascor-bate or by Fe2+/H2O2 (Bozin and others 2006). Chicoric acid(caffeic acid derivatized with tartaric acid) has also been identi-fied in substantial quantities (Lee and Scagel 2009). Additionalantioxidant compounds found in basil are shown in Table 4.

SpicesLike herbs, spices can have significant antioxidative effects (Suhaj

2006). Wojdyło and others (2007) measured total equivalent an-tioxidant capacities and phenolic contents (Folin–Ciocalteu) of32 spices. Major phenolic acids identified in these spices in-cluded caffeic, p-coumaric, ferulic, and neochlorogenic. Predom-inant flavonoids were quercetin, luteolin, apigenin, kaempferol,and isorhamnetin.

Spices can also have antibacterial effects. Shan and others (2005,2007) found that, of 46 spice extracts evaluated, many exhibitedantibacterial activity against foodborne pathogens. Gram-positivebacteria were generally more sensitive than Gram-negative bac-teria. Staphylococcus aureus was the most sensitive, while Echerichiacoli was the most resistant. The antibacterial activity of the extractswas closely associated with their phenolic content.



CinnamonCinnamon (Cinnamonum zeylanicum) contains a number of

antioxidative components including vanillic, caffeic, gallic, pro-tochatechuic, p-hydroxybenzoic, p-coumaricd, and ferulic acidsand p-hydroxybenzaldehyde (Table 5, Figure 1, 2, 4, and 5;(Muchuweti and others 2007). Of a number of herbs and spices(bay leaves, rosemary, sage, marjoram, oregano, cinnamon, pars-ley, sweet basil, and mint) evaluated, cinnamon has been re-ported to have the highest polyphenolic compound concentration(13.7 mg GAE/g; Muchuweti and others 2007). Of 42 commonlyused essential oils, cinnamon bark, oregano, and thyme have beenreported to have the strongest free radical-scavenging abilities (Wenand others 2009). At 5 mg/mL, cinnamon a radical-scavengingactivity of 92% (Muchuweti and others 2007). The major com-ponents responsible for this activity were identified as eugenol,carvacrol, and thymol. Jayaprakasha and others (2003) identified27 compounds in the volatile oil of cinnamon stalks. The volatileoil was 44.7% hydrocarbons and 52.6% oxygenated compounds.Using a β-carotene-linoleate model system, the volatile oil in-hibited 55.9% and 66.9% of the oxidation at 100 and 200 ppm,respectively, compared to the control. The antioxidant capabilityof cinnamon essential oil is stronger than its free radical-scavengingcapacity (Chen 2008). However, it is a better superoxide radicalscavenger than propyl gallate, mint, anise, BHA, licorice, vanilla,ginger, nutmeg, or BHT (Murcia and others 2004).

Cinnamon (bark and leaf) oleoresin can significantly inhibitformation of primary and secondary oxidation products. Singhand others (2007) identified 13 components, which accountedfor 100% of the total amount, in cinnamon bark volatile oil. Thebark oleoresin contained 17 components that accounted for 92.3%of the total amount. The major component in cinnamon barkoleoresin was (E)-cinnamaldehyde (49.9%). Schmidt and others(2006) identified small amounts of β-caryophyllene, benzyl ben-zoate, linalool, eugenyl acetate, and cinnamyl acetate in cinnamonleaf essential oil. The major component identified in cinnamonleaf oil was eugenol (87.2%). Cinnamon leaf oil has a significantinhibitory effect on hydroxyl radicals and acts as an iron chelator ef-ficiently inhibiting formation of conjugated dienes and generationof secondary products from lipid peroxidation at a concentrationequivalent to BHT.

CloveThe primary components of clove (Eugenia caryophyllus) essen-

tial oil are phenylpropanoids such as eugenol, carvacrol, thymol,and cinnamaldehyde (Figure 4; Chaieb and others 2007). Clovealso contains a variety of nonvolatile compounds (tannins, sterols,flavonoids, and triterpenes). Jirovetz and others (2006) identi-fied 23 compounds in clove oil including eugenol (76.8%), β-caryophyllene (17.4%), α-humulene (2.1%), and eugenyl acetate(1.2%). A variety of the antioxidative compounds are shown inTable 5.

Clove essential oil is inhibitory toward hydroxyl radicals andcan chelate iron. Comparing 16 spices, Khatun and others(2006) found that clove had the highest radical-scavenging activityfollowed by allspice and cinnamon. Eugenol has been reportedto have an antioxidative activity equivalent to Trolox, carvacrol(oregano), and thymol (thyme; Dorman and others 2000). Theessential oil scavenges free radicals at concentrations lower thanthose of eugenol, BHT, and BHA alone. Using peroxide valuesand formation of conjugated dienes, Marinova and others (2008)established that in sunflower oil at 100 ◦C, myricetin is a moreeffective and stronger antioxidant than α-tocopherol. Mixtures of Ta

ble

5–Se

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the 2 exhibited a synergistic effect that was optimized in an equalmolar ratio of the 2.

The antioxidant activity of glycosidically bound volatile com-pounds in clove essential oil has been reported to be significantlygreater than that of the volatile aglycones (Politeo and others2010). The glycosides can undergo enzymatic hydrolysis releasingtheir aglycones, therefore, could be considered as potential antiox-idant precursors. Heating at 100 ◦C for up to 6 h increases the per-oxy radical-scavenging activity of clove (Khatun and others 2006).

NutmegJukic and others (2006) isolated glycosidically bound volatiles

from nutmeg and identified free aglycones in the essential oil. Theglycosidically bound and aglycone fractions had only 2 compoundsin common, eugenol and terpinen-4-ol. The aglycone fractionhad stronger antioxidant properties than did the free volatiles fromthe oil. Nutmeg (Myristica fragans and M. argentea) contains ar-genteane, a flavanol diglycoside, which appears to be the primaryantioxidative compound (Calliste and others 2010). Bis-erythroargenteane is a di-lignan that has been isolated from nutmeg mace(the lace-like seed membrane of nutmeg). The argenteane centralmoiety (3,3′-dimethoxy-1,1′-biphenyl-4,4′-diol) appears to oweits free radical-scavenging ability to its ability to release 1 or 2 H

�

(Chatterjee and others 2007; Calliste and others 2010). Nutmegalso contains significant amounts of myristicin and safrole that areresponsible for the characteristic aroma of nutmeg (Fisher 1992).Myristicin and safrole have similar structures: a 6-membered aro-matic ring bound to an oxygenated 5-carbon ring on one sideand a hydrocarbon side chain on the other (Figure 4). After heat-ing (180 ◦C, 10 min), nutmeg oil has a significantly higher freeradical-scavenging activity, compared to basil, cinnamon, clove,oregano, and thyme (Tomaino and others 2005). A variety of theantioxidant compounds found in nutmeg are shown in Table 5.

Ginger, turmeric, and cuminGinger is derived from the root of Zinger officinale. Fresh and

dried ginger contain relatively large amounts of the volatile oilscamphene, p-cineole, alpha-terpineol, zingiberene, and pentade-canoic acid (Figure 4; Tiwari and others 2006; El-Ghorab andothers 2010). The maximum total phenolic contents were ex-tractable with methanol from fresh ginger (95.2 mg/g dry extract)followed by hexane extraction of fresh ginger (87.5 mg/g dry ex-tract). Hydrodistillation produced 23 mg GAE/g (Hinneman andothers 2006). Ginger extract has been shown to have antioxidantactivity almost equal to that of synthetic antioxidants (BHA andBHT; Rehman and others 2003).

Kikuzaki and Nakatani (2006) reported that 12 of the 5gingerol-related compounds and 8 diarylheptanoids isolatedfrom ginger rhizomes exhibit higher antioxidative activity thanα-tocopherol. Authors suggest that this is likely dependent uponside chain structures in addition to substitution patterns on thebenzene ring. Hinneburg and others (2006) have suggested that,for ginger, it may advisable to use extraction media that are ableto extract the lipophilic antioxidant compounds.

Turmeric is a spice derived from the rhizomes the Cur-cuma longa plant, which is a member of the ginger family(Zingiberaceae). Rhizomes are horizontal underground stemsthat send out shoots as well as roots. The bright yellow colorof turmeric is primarily due to fat-soluble, polyphenolic pig-ments known as curcuminoids, primarily curcumin (diferuloylmethane; Priyadarsini and others 2003; Anand and others 2008).Turmeric has been used as a spice and medicinal herb through-

out Asia for centuries. Ground turmeric consists primarily ofcurcumin, dimethoxycurcumin and bis-dimethoxycurcumin, and2,5-xylenol (Zhang and others 2009). Curcumin is an unsaturateddiketone that exhibits keto-enol tautomerism (Anand and others2008). It is a classical phenolic chain-breaking antioxidant, donat-ing H

�

from the phenolic groups rather than from the CH2 group(Ross and others 2000). Jayaprakashaa and others (2006) reportedthat the antioxidant activity of the curcuminoids is curcumin >

BHT, dimethoxycurcumin > bisdemithoxycurcumin. All of thesepolyphenolic molecules have limited water solubility. Curcumin ishighly effective in neutralizing free radicals (Yu and others 2008).At the same concentration, curcumin has about twice the an-tioxidative activity of the polyphenol resveratrol (Aftab and Vieira2009). Turmeric oil has a free radical-scavenging ability compa-rable to vitamin E and BHT (Yu and others 2008). The majorcomponents of turmeric oil responsible for this antioxidant activ-ity are α- and β-turmerone, curlone, and α-terpineol (Carolinaand others 2003).

Heating dry ginger and turmeric and their essential oils at120 ◦C results in different degrees of retention of antioxidant ac-tivity (Tiwari and others 2006). Antioxidant activity of turmericoil is higher after heating while that of ginger oil is lower. Thismay be due to the difference in monoterpene content or to therelease of bound antioxidants caused by the heat treatment. A va-riety of the antioxidant compounds found in ginger and nutmegare shown in Table 5.

Cumin is derived from Cuminum cyminum. The major com-ponents in cumin volatile oil are cuminal, γ -terpinene, andpinocarveol (El-Ghorab and others 2010). Cumin essential oil isbetter at reducing Fe3+ ions than dried or fresh ginger or cumin.

Black pepperBlack pepper (Piper nigrum) is a highly valued spice for its distinct

biting quality that occurs at 1.35 ppm. It has a pungency 150 timesthat of capsaisan (United States Consumer Product Safety Com-mission 1992) due to the alkaloid piperine (Figure 4; Srinivasan2007). The flavor quality is measured by the volatile oil and by thenonvolatile methylene chloride extract, piperine. Piperine stim-ulates the digestive enzymes of the pancreas, enhances digestivecapacity, and reduces gastrointestinal food transit time. Piperinecan also quench free radicals and reactive oxygen species. It canprotect against oxidative damage in vitro. Piperine acts as a hydroxylradical scavenger at low concentrations (Mittal and Gupta 2000).

Kapoor and others (2009) reported that black pepper (P. nigrum)volatile oil contains 54 components that represent about 97% ofthe total weight. β-Caryophylline (30%) is the major compo-nent along with limonene (13%), β-pinene (7.9%), and sabinene(5.9%). Pepper essential oils also contain α- and β-pinene,cyclohexene, 1-methyl-4-(1-methylethylidene)-2,3-cyclohexen-1-ol, limonen-6-ol, (E)-3(10)-caren-4-ol, and t-caryophyllene(Liang and others 2010). The major component of both ethanol-and ethyl acetate-extracted oleoresins is piperine (63.9% and39.0%, respectively, Liang and others 2010). Using peroxide, p-anisidine, and thiobarbituric acid tests, the oil and oleoresinshave been shown to have stronger antioxidant activity thanBHA and BHT (Kapoor and others 2009) but less than that ofpropyl gallate. Gurdip and others (2004) reported that, while ex-tracts were predominantly piperine, piperolein B, piperamide, andguineensine, the predominant compounds in essential oils were β-caryophyllene, limonene, sabinene, β-bisabolene, and α-coapene.Some of the antioxidant compounds found in black pepper areshown in Table 5.



S

O

OH

N

O

S

S-allyl L-cysteine sulfoxide Diallyl sulfide

S

S

S

OH

S

N

O

Allyl trisulfide Allyl-cysteine

Figure 7–Antioxidative sulfur-containingcompounds (S-allyl—cysteine sulfoxide,diallyl sulfide, allyl trisulfide, andallyl-cysteine) in allium plant extracts.

Given that piperine is one of the most effective antioxidativecomponents and also one of the primary aroma compounds inpepper, using extracts of this herb would likely impart unwantedflavors to foods to which they are added unless other antioxidativebut nonaromatic components can be separated from the extract.

Garlic and related herbsGarlic (Allium sativum L.) has been widely used as a foodstuff

since antiquity. It has acquired a reputation as a therapeutic agentand herbal remedy in many cultures to prevent and treat heart andmetabolic diseases, such as atherosclerosis, thrombosis, hyperten-sion, dementia, cancer, and diabetes (Tyler 1993).

Garlic and shallots (Allium ascalonicum) have antioxidant andfree radical-scavenging characteristics and identifiable odors atlow concentrations. They contain 2 main classes of antioxi-dant compounds: flavonoids (flavones and quercetins; Figure 3)and sulfur-containing compounds (allyl-cysteine, diallyl sulfide,and allyl trisulfide; Figure 7). The sulfur-containing amino acidderivative, alliin (S-allyl-L-cystein sulfoxide), can be convertedinto allicin (diallyldisulfide-S-oxide), the compound commonlyassociated with garlic odor, by the enzyme alliinase. Thiosulfi-nates, such as allicin, give garlic its characteristic odor; however,they are not necessarily responsible for all of the various antiox-idative and health benefits attributed to it (Amagase 2006). Okadaand others (2005) have suggested that a combination of the allylgroup (−CH2CH=CH2) and the −S(O)S− group is necessaryfor the antioxidant action of thiosulfinates in garlic extracts. S-allylcysteine, S-allyl mercaptocysteine, and nonsulfur compounds,such as saponins, may contribute to the health benefits (hy-polipidemic, antiplatelet, procirculatory, immune enhancement,anticancer, and chemopreventive activities) associated with garlic.Gorinstein and others (2008) reported that trans-hydroxycinnamicacid (caffeic, p-coumaric, ferulic, and sinapic acids) concentrationsin garlic were twice that in onions. Some of the antioxidant com-pounds found in garlic are shown in Table 6, and sulfur-containingcompounds are shown in Figure 7.

The antioxidative effects of shallots are related primarily to theirphenol content (Leelarungrayub and others 2006). According toNuutila and others (2003), methanol extracts of onions have sig-nificantly higher radical-scavenging activities than garlic and redonion has higher activity than yellow onion. Quercetin content ishighest in red onions (Gorinstein and others 2008). The radical-scavenging activities are positively correlated with the total phe-nolics in these extracts.

Tea extractsThe 3 primary types of tea, green, black, and oolong, are pro-

duced by different processing procedures. Of these types, green teaextracts have the highest total phenolics content, 94% of whichare flavonoids (catechins; Duh and others 2004). Oolong tea con-tains about 18% total phenolics and 4.4% flavonoids. Theaflavinsand thearubigins predominate in black tea. Black tea also con-tains chlorogenic, caffeic, p-coumaric, and quinic acids (Figure 1;Kiehne and Engelhardt 1996). Some of the antioxidant com-pounds found in tea are shown in Table 6.

Much of the antioxidative activity of green tea (C. sinensis)appears to be due to natural flavonoids, tannins, and some vitamins(Abdullin and others 2001). The antioxidant activity is linearlyrelated to the phenol content (Apak and others 2006) that hasbeen reported to be about 450 mg/g (Peschel and others 2007).Catechins in green tea consist primarily of gallic acid derivatives(Chen and others 2007). Catechin flavanols appear to account formore than 80% of the total antioxidant activity of green tea butless than 60% of that of black tea (Gardner and others 1998). Theradical-quenching ability of green tea has been shown to be morethan 20% more effective than that of black tea in both aqueousand lipophilic systems.

In tea extracts, the strongest antioxidant and H2O2-scavengingactivity is due to phenols, with 3 −OH groups bonded to thearomatic ring, adjacent to each other (Sroka and Cisowski 2003).Epigallocatechin, which has 3 adjacent −OH substitutions onthe B ring, has the highest antioxidant activity (Figure 3). In



Tabl

e6–

Sele

cted

anti

oxid

ant

com

poun

dsid

enti

fied

inga

rlic

,tea

,and

grap

esee

dex

trac

t.

Flav

onoi

dsSu

lfur-

cont

aini

ngco

mpo

unds

Hyd

roci

nnam

icac

ids

Oth

ers

Que

rCa

teEp

iEp

icat

echi

nEp

igal

loA

llyl

Dia

llyl

Tri

p-Re

sM

yre

ceti

nqu

inca

tech

inga

llate

cate

chin

galla

tecy

stei

nesu

lfide

sulfi

deCa

ffei

cCo

umar

icFe

rulic

vera

trol

ceti

nRu

tin

Gar

lican

dsh

allo

tsX

XX

XX

XX

XTe

aex

trac

tX

XX

XX

XX

XG

rape

seed

extr

act

XX

XX

XX

XX

Nak

atan

iand

Inat

ani(

1981

),A

roum

aan

dot

hers

(199

2),C

uvel

iera

ndot

hers

(199

4),K

iehn

ean

dEn

gelh

ardt

(199

6),D

orm

anan

dot

hers

(200

0,20

03),

Ahn

and

othe

rs(2

002,

2007

),O

kada

and

othe

rs(2

005)

,Car

rillo

and

Tena

(200

6),Y

anis

hiev

aan

dot

hers

(200

6),C

hen

and

othe

rs(2

007)

,Hat

zidi

mitr

ioua

and

othe

rs(2

007)

,Gor

inst

ein

and

othe

rs(2

008)

,Iac

opin

iand

othe

rs(2

008)

,Her

nand

ez-H

erna

ndez

and

othe

rs(2

009)

,and

Calli

ste

and

othe

rs(2

010)

.

addition to a flavonoid ring, a 3′,4′,5′-trihydroxy (galloyl) groupare required for Fe++ binding in catechins (Khokhar and Owusu-Apenten 2003). These polyphenolic flavonoids are particularlyeffective free radical scavengers (Figure 3; Lien and others 2008).The primary catechin polyphenol [(−)-epigallocatechin-3-gallate]is also the primary peroxyl-radical-scavenging compound in teaextracts (Caldwell 2001; Cabrera and others 2003). In terms of freeradical-scavenging ability, epicatechin gallate > epigallocatechin >

epicatechin (Guo and others 1996). The first 2 compounds have3′,4′,5′-trihydroxy (galloyl) groups while the last does not. Boththeir iron-chelating and free radical-scavenging activities appearto be responsible for the ability of these compounds to protectmembranes from Fe2+/Fe3+-initiated lipid oxidation. In an iron-mediated reaction, Grey and Adlercreutz (2006) demonstratedthat catechin inhibited oxidation better than AA. They concludedthat catechin’s chelating ability, rather than its radical-scavengingmechanism alone, is responsible for the observed antioxidativeactivity.

In more complex food systems, tea catechins can have vary-ing effects. Mitsumoto and others (2005) found that adding teacatechins to raw beef (200 or 400 mg/kg) inhibited (P < 0.05)lipid oxidation to a greater extent than vitamin C (200 or 400mg/kg); however, they increased discoloration in cooked beefand chicken meat. Chen and others (1998) reported that greentea catechin extract, consisting primarily of 4 epicatechin iso-mers, was much more antioxidative than rosemary extract whenadded to canola oil, pork lard, and chicken fat. In maize (corn)oil triglycerides, Huang and Frankel (1997) found that epigallo-catechin (140 M), epigallocatechin gallate, and epicatechin gallatewere better antioxidants than either epicatechin or catechin. Bothgallic acid and propyl gallate were more effective than epicate-chin and catechin. However, in a maize oil-in-water emulsion,all tea catechins, gallic acid, and propyl gallate were prooxidative(5 and 20 M) accelerating hydroperoxide and hexanal formation.The improved antioxidant activity of tea catechins in liposomes,compared with emulsions, may be due to the greater affinity ofthe polar catechins toward the polar surface of the lecithin bilay-ers, thus affording better protection (Hatzidimitrioua and others2007). In a model system mixture of the flavanols, in the sameconcentrations as they occur in the tea extracts, the antioxidantpotential has been shown to be a simple summation of the activ-ity of the individual components with no apparent synergism orantagonism occurring (Gardner and others 1998).

Alkyl compounds with double bond(s), such as 3,7-dimethyl-1,6-octadien-3-ol in green tea extracts and heterocyclic com-pounds (furfural) in roasted green tea extracts, are majorvolatile constituents that also exhibit some antioxidative activity(Yanagimoto and others 2003).

Grape seed extractBecause red wines are produced from red grapes, the antioxi-

dant capacity and chemical composition are related to the grapes.The antioxidant activity of red wines is associated with the con-tent of polyphenols such as flavonoids, phenolic acids, stilbenes,coummarines, and lignoids (Radovanovic and others 2009). Thephenolic composition varies greatly due to grape variety, envi-ronmental and climate conditions, soil type, degree of ripeness,and winemaking process (Table 6; Jayaprakasha and others 2001;Hatzidimitrioua and others 2007; Lachman and others 2007;Iacopini and others 2008; Rababah and others 2008; Xu and oth-ers 2010;). Touns and others (2009) reported wide variations inthe contents of total phenols (122 to 441 mg GAE/g), flavonoids



17 to 48 mc epicatechin [EC]/g), and tannins (15 to 37 mc EC/g)in the methanolic extracts from seeds of 3 varieties of grapes.

Phenolic compounds in grape seeds and skins include cate-chins, epicatechins, epicatechin-3-O-gallate, phenolic acids, caf-feic acid, quercetin, myricetin, proanthocyanidins, and resveratrol(Figure 1, 3, and 4; Jayaprakasha and others 2001; Hatzidimitri-oua and others 2007). Many have strong antiradical activity. Mostof the phenolic compounds found in red wines are derived fromthe condensation of flavan-2-ol into oligomers (proanthocyani-dins) and polymers (condensed tannins). Resveratrol, quercetin,and rutin are generally found in grape skin extracts, while cat-echin and epicatechin are found in the seeds (Figure 3 and 6).The phenolic content of grape seeds defatted with hexane thenextracted with methanol and dried under vacuum has been re-ported to be about 5 mg/100 g, while the anthocyanin content isbetween 0.14 and 0.68 g/100 g (Rababah and others 2008).

Iacopini and others (2008) assessed the antioxidant activity ofthe extracts and pure compounds using 2 different in vitro tests:scavenging of the stable DPPH radical and of authentic perox-ynitrite (ONOO−). Antioxidant activities of grape seed extractranged from 66.4% to 81.4%, compared to vitamin E that rangesfrom 90.3% to 94.7%. Monophenols, quercetin, rutin, and resver-atrol may act either synergistically or antagonistically dependingon their concentrations and the reaction temperature. Grape seedextract has been shown to inhibit both lipid hydroperoxide andpropanal formation in an emulsion system (Hu and Skibsted 2002).Oligomeric procyanidins may be better antioxidants than theirmonomeric counterparts due to their ability to concentrate wherethe oxidative reaction is likely to occur.

Resveratrol (trans-3,4′,5-trihydroxystilbene), produced primar-ily in the grapevine, is present in various parts of the grape,including the skin. It has strong antioxidant activity exceedingthat of propyl gallate, vanillin, phenol, BHT, and α-tocopherol(Murcia and Martinez-Tome 2001). This may be because it hasmore phenolic rings (2 compared with 1) than propyl gallate,phenol, and BHT, and because it has more −OH groups thanα-tocopherol (3 compared with 1). Resveratrol inhibits peroxida-tion in a concentration-dependent manner. However, it does notscavenge hydroxyl radicals or does it react with H2O2, making it aninefficient catalyst of subsequent oxidation (Murcia and Martinez-Tome 2001). Some of the antioxidant compounds found in grapeseed extract are shown in Table 6.

Soares and others (2003) demonstrated that resveratrol,vitamins C and E, BHT, and propyl gallate were all able to signifi-cantly inhibit the oxidation of β-carotene by hydroxyl free radicals.Polyphenolic fractions from grape pomace can repair α-tocopherolby reducing the α-tocopheroxyl radical (Pazos and others 2009).

Most of the phenolic compounds in fresh wine are derived fromcondensation of flavan-3-ol into oligomers (proanthocyanidins)and polymers (tannins; Granato and others 2011). Granato andothers (2011) reported that the primary phenolics exerting antiox-idant effects (DPPH and ORAC assays) in Brazilian red wines werenonanthocyanin flavonoids. Anthocyanins present in these wineswere present solely in their monomeric form and ranged fromabout 9 to 237 mg/mL. Flavonoid content varied from 520 to1795 mg catechin equivalents [CTE]/L. However, after evaluating80 Spanish red wines, Rivero Perez and others (2008) found thatthe free anthocyanin fraction is the primary fraction responsiblefor antioxidant capacity and is correlated with electron transferprocesses.

Pazos and others (2006) evaluated the effectiveness of a grapephenol fraction, isolated grape procyanidins, hydroxytyrosol (from

olive oil), and propyl gallate in inhibiting lipid oxidation in afish (hake) microsomal model system. Oxidation was initiated byhemoglobin, enzymatic NADH iron and nonenzymatic ascorbateiron. The relative antioxidant efficiency was independent of theprooxidant system and was isolated grape procyanidin > propylgallate > grape phenolic extract > hydroxytyrosol. Antioxidativeeffectiveness was positively correlated with incorporation of thesubstance into microsomes. However, polarity appeared to playless of a role in inhibition of hemoglobin oxidation by pheno-lics underscoring the fact that an exogenous antioxidant must beincorporated into membranes where unsaturated fatty acids andiron-reducing enzymes are located in order to be effective. Poianaand others (2008) demonstrated that during the ageing of red wine,polymeric anthocyanins increased from about 9% to over 75% after6 mo, while monomeric anthocyanins decreased from over 75% toless than 24%. Total antioxidant capacity decreased and was highlycorrelated with the monomeric anthocyanin fraction (r > 0.98);however, free radical-scavenging ability increased and was highlycorrelated with the polymeric anthocyanin fraction.

Granato and others (2010) also evaluated the antioxidant activityand the phenolic content of red wines and verified that ORACvalues correlated well to flavonoid content (r = 0.47; P = 0.01),total phenolics (r = 0.44), and DPPH (r = 0.67). DPPH valuesalso correlated well to the content of flavonoids (r = 0.69), totalphenolic compounds (r = 0.60), and nonflavonoid compounds (r =0.46) (in beers; Granato and others 2011).

The Stereochemistry of FlavanonesEnantiomers are molecules that are mirror images of each an-

other but cannot be superimposed onto one another. Moleculesexhibit stereoisomerism (enantiomers) because they have one ormore chiral centers. A chiral center results from the presence of anassymetrical carbon atom, that is, one that is attached to 4 differ-ent atoms or 4 different groups of atoms (making its mirror imagenonsuperimposable). Enantiomers rotate the plane of polarizedlight in opposite directions.

Enantiomer names use the R/S system. This system involves noreference but labels each chiral center R or S using a system inwhich its substituents are each assigned a priority, according to theCahn-Ingold-Prelog priority rules (Cahn and others 1966), basedon atomic number. If the center is oriented so that the lowestpriority of the 4 substituents is pointed away from a viewer, theviewer will then see 2 possibilities: if the priority of the remaining3 substituents decreases in a clockwise direction, it is labeled R(rectus), and if it decreases in a counterclockwise direction, it is S(sinister).

Flavanones can have chiral carbon atoms; therefore, they can ex-ist as S- and R-enantiomers. These enantiomers can be producedin different quantities in different plant materials under differentgrowing conditions (Yanez and others 2005, 2008, 2007). Theycan have different effects in both biological and inorganic systems.For these reasons, separating and quantifying them has been ofinterest to the medical, biological, and agricultural industries inthe recent past.

The flavanone glycosides naringin and neohesperidin foundin some citrus species have a chiral center in the C-2 positionof the flavanone moiety (Uchiyama and others 2008; Figure 8).The flavanone hesperetin, the aglycone of hesperidin and majorflavonoid in oranges, contains a chiral C-atom, so it can alsoexist as an S- and R-enantiomer. The 2S-herperidin and its S-hesperitin aglycone predominate in nature (Uchiyama and others2008).



O

O

OH

OH

HO

O

O

O

O

HO

O OH OH

OH

O O

HO

OH

OH

OH

OH

Hesperitin Naringen

O O O O

O

HO

OH

OH

HO

OH

OH

O OH

OH

HO OH

Neohesperidin

O O O

O

OO

HO

OH

OH

HO

OH

OH

OH

OH

OH

OH

Hesperidin

Figure 8–Natural antioxidants that exist as stereoisomers (hesperitin, naringin, neohesperidin, and hesperidin).

Enantiomers can react with other compounds or other enan-tiomers in different ways or at different rates. Brand and oth-ers (2010) have demonstrated small, but significant, differencesin the metabolism and transport characteristics, and bioactivitybetween S- and R-hesperetin. Naringin, the major flavanone-7-O-glycoside of sour orange, is responsible for the bitter tasteof the fruit (Caccamese and others (2010). The relative ratios ofnaringin and neohesperidin to their C-2 epimers varies depend-

ing on species, maturity, and processing. Separation of naringinfrom neohesperidin is complicated by the presence of stereoiso-mers (Belboukhari and others 2010). Takemoto and others (2008)developed a high-performance liquid chromatography (HPLC)method using UV detection for the stereospecific analysis of theflavan, sakuranetin, found in grapefruit and oranges. StereospecificHPLC methods have been developed for separation of epimers intea, grapes, orange juice, and C-2 epimers from other sources



(Uchiyama and others 2008; Caccamese and others 2010; Vega-Villas and others 2008; Kim and others 2009; Belboukhari andothers 2010).

Si-Ahmed and others (2010) reported that different mo-bile phases in different ratios are required to accomplishenantiomeric and diastereomeric separation of a variety offlavanones (flavanone, 2′-hydroxyflavanone, 4′-hydroxyflavanone,6-hydroxyflavanone, 7-hydroxyflavanone, 4′-methoxyflavanone,6-methoxyflavanone, 7-methoxyflavanone, hesperetin, hes-peridin, naringenin, and naringin). Others have reported simi-lar differences in chiral discrimination ability (toward flavanones)depending on the buffer and alcohol modifier enantioselectivity(Cirilli and others 2008). Abbate and others (2009) described amethod for assessing configurational and conformational proper-ties (of naringenin) using vibrational circular dichroism.

The stereoselectivity of chiral flavanones and epimers has sig-nificant biological effects in terms of their pharmacological activ-ity and disposition in humans and livestock. Gardana and others(2009) reported that some human intestinal bacteria can transformdiadzein to equol, O-desmethylangolensin, or dihydrodaidzein.Diet has a clear effect. A diet lower in fiber, vegetables, and cere-als and higher in lipids from animal sources increases productionof equol. These stereoselective differences in the chiral forms offlavonone antioxidants may result in differences in antioxidativeeffects of the various epimers depending on the matrix and oxi-dizing group. For these reasons, a concerted effort is being madeto separate these chiral compounds and to evaluate their specificcharacteristics under defined conditions.

Effects of ProcessingEndogenous antioxidant systems (enzymatic) can be damaged

during food processing (particle size reduction and heating), bycertain ingredients (salts and organic acids), and by storage con-ditions (presence of oxygen) such that they are ineffective (Chenand others 1998). NaCl, in particular, reduces the activity of theantioxidant enzymes catalase, glutathione peroxidase, and superox-ide dismutase that reduces their capacity to perform antioxidativefunctions (Lee and others 1997). Ingredients, such as AA and citricacid, can work synergistically with flavonoid antioxidants.

Spices and herbs can be added to foods in various forms: whole,ground, or as isolates from their extracts. Extracting antioxidantcomponents from a complex matrix depends on the solubility ofthe extractant, the solvent, and the presence of other substancesthat may compete with the extraction process, and the extractionprocess itself (vacuum, distillation, pressure, and so on). Becausethese substances are aromatic, pungent food ingredients, they mayor may not be desirable in a nonflavoring (antioxidant or other)application (Ruberto and others 2000; Teissedre and Waterhouse2000). For example, even at low concentrations, some componentsof rosemary essential oil (verbenone, borneol, and camphor) canimpart a rosemary odor to foods (Carrillo and Tena 2006). Solidrosemary extract can contain >356 μg/g verbenone, 190 μg/gborneol, and >135 μg/g camphor (Carrillo and Tena 2006).

ExtractionBecause many antioxidants are unstable to oxygen and endoge-

nous enzymes, most are extracted from freeze-dried plant materi-als. Selecting an appropriate extraction procedure can increase theconcentration of the antioxidant compound. Extraction using edi-ble oil or fat is relatively simple. Herbs and spices can be mixed withfats, oils, or medium-chain triglycerides, allowed to extract underdefined time/temperature control, then filtered for use (Pokorny

and others 2001). Three primary extraction techniques are used forpolyphenols: solvents, solid-phase extraction, and supercritical ex-traction. Using a Soxhlet apparatus combines percolation and im-mersion that increases extraction efficiency. Several extractions canbe accomplished with solvents having different polarities (petrolether, toluene, acetone, ethanol, methanol, ethyl acetate, and wa-ter). Methanol/water/HCl (70:29:1, v/v/v) has been shown to bethe best among several solvents evaluated for extracting phenolicsfrom grape seed (Xu and others 2010). Grinding in a mortar inliquid nitrogen provides uniform particle size allowing for a moreconsistent extraction.

Ultrasound can be used to assist liquid solvent extraction. Xuand others (2010) reported that sequential sonication was a pre-ferred to mechanical agitation as an extraction method for assessingphenolic content in grapeseed. Supercritical CO2 extraction canalso be used (Schwarz and others 2001).

Hydrodistillation of plant materials has several advantages. Theessential oils that carry the intrinsic flavor of a spice can be removedand polyphenols, primary antioxidant compounds, are concen-trated. In addition, the hydrodistilled compounds are generallymore soluble in aqueous media than are those extracted usingorganic solvents. They are often more soluble than synthetic an-tioxidants as well. Hydrodistillation also avoids potential residuesfrom organic solvents. Hydrodistilled extracts have also been re-ported to have a variety of functional effects in foods and in humanhealth (Hinneburg and others 2006). Optimizing the extractionprocess could lead to even better results.

The distillation process can also concentrate antioxidant com-ponents. Naz and others (2011) found that deodorizer distillatesfrom sunflower oil processing were richer in tocopherols than thedeodorized oil itself. The implication is that, while the distillationprocess removes unwanted materials from the oil, it may, in fact,concentrate some of the antioxidants.

Heat treatmentWhen we think of processing, heat treatment is often the first

process that comes to mind.Antioxidative activity of a given compound may increase, de-

crease, or remain unchanged as a function of temperature. Stabilityof an antioxidant to heat is advantageous in the food industry, sincemany fat- and oil-containing foods are heated during processingand since heat is often the initiator of lipid oxidation. At 80 ◦C,the antioxidative activity of δ-tocopherol is about twice that of α-tocopherol; however, it decreases as temperature increases from 80to 150 ◦C. Antioxidative activity of α-tocopherol remains fairlyconstant between 80 and 110 ◦C, decreasing only at tempera-tures above 110 ◦C. Neither retains their antioxidative activity at150 ◦C.

Ginger extract has good thermal stability and inhibits morethan 85% of linoleic acid peroxidation when heated at 185 ◦C for120 min (Rehman and others 2003). Heating (120 ◦C) dry gingerand turmeric essential oils results in different degrees of antioxidantactivity retention. The antioxidant activity of turmeric oil is higherafter heating (120 ◦C), unlike ginger oil that loses antioxidantactivity (Tiwari and others 2006). Turmeric oil contains a higherconcentration of monoterpenes than does ginger oil; however,release of bound antioxidants by the heat treatment should not beruled out.

Adding antioxidants to livestock dietsIncluding herb distillates into livestock diets can have positive

effects. Moclino and others (2008) found that feeding a steam



distilled rosemary by-product to ewes increased rosmarinic acid,carnosol, and carnosic acid content in the meat. Fresh meat fromthese animals had higher total ferric reducing antioxidant powerand lower DPPH values than controls indicating that the rosemarydistillate partitioned into the meat tissues and reduced susceptibil-ity to oxidation. McCarthy and others (2001) have shown similarresults with pigs. Boler and others (2009) found that feeding vita-min E to pigs increased pork stability during storage. Simitzis andothers (2008) found that meat from lambs fed a feed that had beensprayed with oregano essential oil (1 mL/kg) was much more stableto lipid oxidation during both refrigerated and frozen storage thanthat from controls. Gobert and others (2010) found that addingantioxidants to diets of cattle fed a polyunsaturated fatty acid(PUFA)-rich diet improved lipid stability in steaks; the combina-tion of vitamin E and plant extracts rich in polyphenols was moreefficient than vitamin E alone indicating some synergism betweenthe 2.

Effects of the food matrix and ingredientsNatural plant antioxidants can protect food components from

oxidation under the stress of heating and storage. However, theinherent characteristics (ionic strength and pH) of the food, thefood matrix (emulsion, foam, aqueous, and protein), and ingredi-ents can influence antioxidant effectiveness.

Vitamin E added to water-based food systems in an oil carrierconcentrates in the neutral lipid fraction rather than the polar lipidfraction and is not an effective antioxidant. However, δ-tocopheroladded using a polar carrier can be incorporated into the phos-pholipid fraction and is an effective antioxidant (Wills and others2007). In a lard model system, the antioxidative activity of thetocopherols is temperature dependent (Reblova 2006). Wanatabeand others (2010) demonstrated that, in a methyl lineoleate/wateremulsion, the effectiveness of AA and acyl ascorbates dependedon whether the oxidation process was initiated by an oil-solubleprooxidant or a water-soluble prooxidant. The AA concentratedin the aqueous phase and suppressed oxidation to a greater de-gree at the oil/water interface when the prooxidant was watersoluble. Docecanoyl and hexadecanoyl ascorbates dissolved in theoil phase and suppressed oxidation the oil phase (droplets) ratherthan at the interface. Increasing the pH appeared to enhance theelectron-donating ability of AA in the water phase ultimately af-fecting oxidation. Hexadecanoyl ascorbate in the oil phase was notsusceptible to these pH effects. Authors suggest that another expla-nation may be destabilization of the emulsion through flocculationand coalescence of the oil droplets at low pH.

Thymol can prevent loss of α-tocopherol (in oil) followingheating at 180 ◦C for 10 min (Tomaino and others 2005). Using alipophilic model system, Lee and Shibamoto (2002) demonstratedthat volatile extracts of thyme (and basil) inhibited the oxidationof hexanal for 40 d. These extracts also inhibited methyl linoleatedeterioration at 40 ◦C. In sunflower oil, aroma detection thresholdsof carvacrol, thymol, and p-cymene 2,3-diol have been reported tobe 30, 124, and 794 ppm, respectively (Bitar and others 2008). p-Cymene 2,3-diol at 335 ppm imparted no negative flavor changesand reduced oxidation by more than 46%.

Estevez and others (2008) evaluated several phenols (gallic acid,cyanidin-3-glucoside, (+)-epicatechin, chlorogenic acid, genis-tein, and rutin) and α-tocopherol in terms of anti- or prooxidativeeffects of oil-in-water emulsions containing myofibrillar proteins(1%). Gallic acid, cyanidin-3-glucoside, and genistein were themost efficient inhibitors of lipid and protein oxidation. They con-

cluded that the nature and conformation of the proteins as wellas the chemical structure of the phenols influenced the overalleffect.

Antioxidant content of raw materials can change over time andare likely related to storage conditions. Hatzidimitrioua and others(2007) reported that total phenol content of grape seeds decreasesduring storage. Changes were minor for samples stored at less than55% relative humidity; however, high humidity (75%) accelerateddegradation resulting in a 50% reduction of total phenol content.Based on the continuous gallic acid release, authors suggested thatthis degradation was related to hydrolytic reactions. Modificationsof the storage process would be expected to enhance retention ofantioxidative compounds in grape seeds.

Ingredients, such as salt, can act as prooxidants in food systems;however, antioxidants can help reduce it. Brannan (2008) foundthat grape seed extract helps to mitigate the prooxidative effectsof NaCl in stored ground chicken without affecting moisturecontent or pH. The author suggests that grapeseed extract mayalter the effect of NaCl on protein solubility in salted chickenpatties. Whether it affects physicochemical interactions in cookedmeat quality remains to be assessed.

Akarpat and others (2008) demonstrated that adding a hot waterextract of rosemary (10%) to ground beef containing salt (1.5%)protected color and preserved oxidative quality during frozen stor-age (120 d). Fasseas and others (2008) found that essential oils fromoregano and sage added to ground beef and pork (3% w/w) re-duced oxidation. The effect was even more dramatic in cookedmeat than in raw meat.

The antioxidant components of rosemary, sage, basil, black pep-per, garlic, and onion appear to be relatively stable. Microwavetreatment of these herbs has no effect on reducing power or iron-chelating capacity (Bertelli and others 2004). However, the effectson other components, such as flavor components and pigments,are unknown.

Marinating and cooking (chicken) significantly reduces the an-tioxidant activities of marinating sauces and consequently reducesthe amounts of antioxidant available (Thomas and others 2010).Marinating chicken (in herb and spice-based marinades) prior tocooking reduced the total antioxidant activity (45% to 70%) orig-inally present in the sauce. This may be due to the ionic effects ofvarious salts typically included in marinades, the effects of reducedpH on the phenolic components of the marinades, and/or tothe interactions between antioxidants or between antioxidants andprotein. Loss of antioxidant activity due to cooking may reflect theprotective action of antioxidants on proteins (which are denaturedby heating) or their protective action toward other components(vitamins).

In addition to reducing lipid oxidation, antioxidants may haveother benefits in food systems. Adding rosemary essential oiland/or citrus fiber washing water to bologna has been shownto lower the levels of residual nitrite (Viuda-Martos and others2010). Flavonoids, hesperidin, and narirutin were identified inthe bologna with hesperidin concentrations being higher thannarirutin concentrations. The preferred (sensory) sample was thatwhich contained 50 g/kg citrus fiber water and 200 mg/kg rose-mary essential oil.

There are many types of food matrices to which these antioxi-dant compounds might be added and many types of processing thatthe product might then undergo. There are currently no generalguidelines as to what/when to use plant extracts in food matrices.More studies are necessary to elucidate that substances are effectivein what systems and under what condition.



SynergismCombining antioxidants may increase their effectiveness. Smet

and others (2008) found that dietary synthetic antioxidants com-bined with α-tocopherol were more effective than rosemary, greentea, grape seed, or tomato extracts (100 to 200 ppm) alone or incombination in sparing tocopherols oxidation and in preventingoxidation of fresh frozen chicken patties. It has been proposedthat the mixed free radical acceptors involve 2 antioxidants: onethat reacts with the peroxy radical (and is consumed) and a 2ndthat regenerates the 1st, effectively sparing. Phenolic antioxidantsand AA appear to work synergistically in this way (Uri 1961).

(1) ROO�

+ A:H = ROO:H + A�

(2) A�

+ B:H = A:H + B�

.

Some acidic compounds, such as AA and citric acid, can exerta synergistic effect when added along with polyphenolic antiox-idants. These acidic compounds chelate metals. These synergistsform an antioxidant radical synergist complex (A:S) such that nei-ther the antioxidant radical (A

�

) nor the synergist radical (S�

) cancatalyze oxidation reactions. This chemical association suppressesthe antioxidant radical’s ability to assist in the breakdown of lipidperoxides (Aurand and Woods 1979).

Addition of anthocyanin can prevent oxidation of AA by metalions such as copper (Sarma and others 1997). Anthocyanin notonly chelates metal ions, but also forms an AA (copigment-metal-anthocyanin) complex that may be the basis for its antioxidativeactivity. Because of the number of −OH groups on the aro-matic rings, and because of their water solubility, anthocyanins arepH-sensitive. In a basic solution, the −OH groups can give upH+; in a more neutral environment, they can donater H

�

to anoxidizing lipid (ROO

�

). For this reason, the antioxidative capacityof an anthocyanin is dependent on the anthocyanin itself (num-ber and location of −OH groups), the pH of the surroundingenvironment, and the other components of the system (metals,continuous phase).

Lee and others (2005) found that combinations of chelators(sodium tripolyphosphate or sodium citrate) with reductants (ery-thorbate), and/or free radical scavengers (BHA and rosemary ex-tract) were effective antioxidants. The combination of rosemaryand erythorbate was most effective in delaying lipid oxidation inground beef. The rosemary/citrate/erythorbate combination wasmost effective in stabilizing color and delaying lipid oxidation.These findings indicate that combining a reductant with a freeradical scavenger is more effective at preventing lipid oxidationthan either alone.

In a mixture of 3 monophenols (catechin, resveratrol, and/orquercetin) derived from grapeseed, Pinelo and others (2004) foundan initial increase in antioxidative activity followed by a subse-quent decrease for all solution combinations. They also reported apossible synergy between quercetin, rutin, and resveratrol towardONOO−. The effect was additive for catechin and epicatechin.These compounds may be acting independently, while other com-binations may react with each other.

Granato and others (2010) found that (in brown ales) flavonoids,total phenolics, and nonflavonoid phenolics (hydroxycinnamatesand hydroxybenzoates), derived from both the malt and the hops,are strongly correlated with antioxidant activity (ORAC andDPPH). Ghiselli and others (2000) have shown that beer increasesserum antioxidant capacity. Ethanol increases absorption of phe-nolic acids. However, the increase in antioxidant capacity is notdue to either ethanol or phenolic acids alone, but rather becauseof a synergistic effect between the 2.

Regulatory Status of Extracts, Concentrates, andResins

Synthetic antioxidants (BHA, BHT, and EDTA) are regulatedby the Food and Drug Administration (FDA) as direct food addi-tives. They may be used alone or in combination not to exceed0.02% (2 ppm) of the final product in specified food products(21CFR172.110). These antioxidants are considered to be safeand suitable ingredients for use in meat, poultry, and egg products,alone or in combination, not to exceed 0.02% of the fat content(FSIS Directive 7120.1. revision 5).

Some herb and spice extracts and oleoresins are Generally Rec-ognized As Safe (GRAS). Some are considered to be indirect ad-ditives (21 CFR Vol. 3. Part 101); as such, solvents permitted forthe extraction process and solvent residues allowed are specified.Some extracts, concentrates, and resins are regulated by the FDA“Dietary Supplement Health and Education Act of 1994” and areconsidered to be one (or more) of several defined dietary ingre-dients (a vitamin, a mineral, an herb or other botanical, aminoacid, a dietary substance for use by man to supplement the dietby increasing the total dietary intake, or a concentrate, metabolite,constituent, extract, or combination of any ingredient described inclause (A), (B), (C), (D), or (E) and is excluded from regulation asa food additive. Extracts, concentrates, and resins are also regulatedunder the Food Labeling Regulation, Amendments; Food Reg-ulation Uniform Compliance Date; and New Dietary IngredientPremarket Notification Final Rule (1997). If they are added tocause flavor or color changes, they are regulated as such and specificquantities allowable for use in various foods are set forth. Based onthe number of various classifications under which an extract, con-centrate or resin could be covered, allowable use levels vary widely.

SummaryPlant and animal tissues contain unsaturated fatty acids, primar-

ily in the phospholipid fraction of cell membranes. These lipidsare especially susceptible to oxidation because of their electron-deficient double bonds. The breakdown products of oxidation canproduce off-odors, new flavors, loss of nutrient content, and colordeterioration. To manufacture high-quality, stable food products,the most effective solution is often the addition of antioxidants,either synthetic or natural, which can serve as “chain breakers,” byintercepting the free radicals generated during various stages of ox-idation or to chelate metals. Chain-breaking antioxidants are gen-erally the most effective. A common feature of these compoundsis that they have one or more aromatic rings (often phenolic) withone or more −OH groups capable of donating H· to the oxidiz-ing lipid. Synthetic antioxidants, such as BHA, BHT, and propylgallate, have one aromatic ring. The natural antioxidants AA andα-tocopherol each have 1 aromatic ring as well. However, many ofthe natural antioxidants (flavonoids and anthocyanins) have morethan 1 aromatic ring. The effectiveness of these aromatic antiox-idants is generally proportional to the number of −OH groupspresent on the aromatic ring(s). Depending on the arrangementof the −OH groups, these compounds may also chelate prooxida-tive metals. The facts that they are natural, and have antioxidativeactivity that is as good or better than the synthetic antioxidants,makes them particularly attractive for commercial food processorsbecause of consumer demand for natural ingredients.

ReferencesAbbate S, Burgi LF, Castiglioni E, Lebon F, Longhi G, Toscano E,Caccamese S. 2009. Assessment of configurational and conformational



properties of naringenin by vibrational circular dichroism. Chirality21(4):436–41.

Abdullin IF, Turova EN, Budnikov GK. 2001. Coulometric determination ofthe antioxidant capacity of tea extracts using electrogenerated bromine.Zhurnal Analiticheskoi Khimi 56(6):627–9.

Acree T, Arn H. 2004. Flavornet. Available from: http://www.flavornet.org,c©Datu Inc. Accessed Jun 2008.

Aftab N, Vieira A. 2009. Antioxidant activities of curcumin and combinationsof this curcuminoid with other phytochemicals. Phytother Res 24(4):500–2.

Agati G, Matteini P, Goti A, Tattini M. 2007. Chloroplast-located flavonoidscan scavenge singlet oxygen. New Phytol 174(1):77–81.

Ahn J, Grun IU, Fernando LN 2002. Antioxidant properties of natural plantextracts containing polyphenolic compounds in cooked ground beef. J FoodSci 67(4):1364–9.

Ahn J, Grun IU, Mustapha A. 2007. Effects of plant extracts on microbialgrowth, color change, and lipid oxidation in cooked beef. Food Micro24:7–14.

Akarpat A, Turhan S, Ustun NN. 2008. Effects of hot water extracts frommyrtle, rosemary, nettle and lemon balm leaves on lipid oxidation and colorof beef patties during frozen storage. J Food Process Preserv 32(1):117–32.

Alamed J, Chaiyasit W, McClements DJ, Decker EA. 2009. Relationshipsbetween free radical scavenging and antioxidant activity in foods. J AgricFood Chem 57(7):2969–76.

Allam SSM, Mohamed HMA. 2002. Thermal stability of some commercialnatural and synthetic antioxidants and their mixtures. J Food Lipids9(4):277–93.

Amagase H. 2006. Clarifying the real bioactive constituents of garlic. J Nut136(Suppl 3):716S–25S.

Anand P, Thomas SG, Kunnumakkara AB, Sundaram C, Harikumar KB,Sung B, Tharakan ST, Misra K, Priyadarsini IK, Rajasekharan KN,Aggarwal BB. 2008. Biological activities of curcumin and its analogues(congeners) made by man and mother nature. Biochem Pharm7(6):1590–611.

Aoki T, Wada S. 2003. Phenolics composition and antioxidant activity ofsweet basil (Ocimum basilicum L. J Agric Food Chem 51(15):4442–9.

Apak R, Guclu K, Ozyurek M, Karademir SE, Ercag E. 2006. The cupricion reducing antioxidant capacity and polyphenolic content of some herbalteas. Internat J Food Sci Nut 57(5–6):292–304.

Arouma OI, Halliwell B, Aeschbach R, Loligers J. 1992. Antioxidant andpro-oxidant properties of active rosemary constituents: carnosol and carnosicacid. Xenobiotica 22:257–68.

Aurand LW, Woods AE. 1979. Lipids. Chapter 5. In: Aurand LW, WoodsAE, editors. Food chemistry. Westport, Conn.: The AVI PublishingCompany, Inc. p 125–6.

Bak I, Lekli I, Juhasz B, Varga E, Varga B, Gesztelyi R, Szendrei L, Tosaki A.2010. Isolation and analysis of bioactive constituents of sour cherry (Prunuscerasus) seed kernel: an emerging functional food. J Med Food 13(4):905–10.

Belboukhari N, Cheriti A, Roussel C, Vanthuyne N. 2010. Chiral separationof hesperidin and naringin and its analysis in a butanol extract of Launeaearborescens. Nat Prod Res 24(7):669–81.

Bendini A, Toschi TG, Lercker G. 2002. Antioxidant activity of oregano(Origanum vulgare L.) leaves. Italian J Food Sci 14(1):17–24.

Berger RG. 2009. Biotechnology of flavours-the next generation. BiotechLet 31(11):1651–9.

Bertelli D, Plessi M, Miglietta F. 2004. Effect of industrial microwavetreatment on the antioxidant activity of herbs and spices. Italian J Food Sci16(1):97–103.

Bitar A, Ghaddar T, Malek A, Haddad T, Toufeili I. 2008. Sensorythresholds of selected phenolic constituents from thyme and theirantioxidant potential in sunflower oil. J Am Oil Chem Soc 85(7):641–6.

Boler DD, Gabriel SR, Yang H, Balsbaugh R, Mahan DC, Brewer MS,McKeith FK, Killefer J, 2009. Effect of different dietary levels ofnatural-source vitamin E in grow-finish pigs on pork quality and shelf life.Meat Sci 83(4):723–30.

Bozin B, Mimica-Dukic N, Simin N, Anackov G. 2006. Characterization ofthe volatile composition of essential oils of some Lamiaceae spices and theantimicrobial and antioxidant activities of the entire oils. J Agric FoodChem 54(5):1822–8.

Brand W, Shao J, Hoek-van den Hil EF, van Elk KN, Spenkelink B, deHaan LH, Rein MJ, Dionisi F, Williamson G, van Bladeren PJ, Rietjens

IM. 2010. Stereoselective conjugation, transport and bioactivity of S- andR-hesperetin enantiomers in vitro. J Agric Food Chem 58(10):6119–25.

Brannan RG. 2008. Effect of grape seed extract on physicochemicalproperties of ground, salted, chicken thigh meat during refrigerated storageat different relative humidity levels. J Food Sci 73(1):C36–C40.

Brewer MS, Prestat C. 2002. Consumer attitudes towards issues in foodsafety. J Food Safety 22(2):67–85.

Brewer MS, Russon C. 1994. Consumer attitudes towards food safety issues.J Food Saf 14:63–76.

Brown JE, Kelly MF. 2007. Inhibition of lipid peroxidation by anthocyanins,anthocyanidins and their phenolic degradation products. Eur J Lipid SciTechno 109(1):66–71.

Buricova L, Reblova Z. 2008. Czech medicinal plants as possible sources ofantioxidants. Czech J Food Sci 26(2):132–8.

Cabrera C, Gimenez R, Lopez MC. 2003. Determination of tea componentswith antioxidant activity. J Agric Food Chem 51(15):4427–35.

Caccamese S, Bianca S, Santo D. 2010. Racemization at C-2 of naringin insour oranges with increasing maturity determined by chiralhigh-performance liquid chromatography. J Agric Food Chem55(10):3816–22.

Cahn RS, Ingold CK, Prelog V. 1966. Specification of molecular chirality.Angew Chem Intl Ed 5(4):385–415. DOI:10.1002/anie.196603851.

Caldwell CR. 2001. Oxygen radical absorbance capacity of the phenoliccompounds in plant extracts fractionated by high-performance liquidchromatography. Analyt Biochem 293(2):232–8.

Calliste CA, Kozlowski D, Duroux JL, Champavier Y, Chulia AJ, TrouillasP. 2010. A new antioxidant from wild nutmeg. Food Chem 118(3):489–96.

Carrillo JD, Tena MT. 2006. Determination of volatile compounds inantioxidant rosemary extracts by multiple headspace solid-phasemicroextraction and gas chromatography. Flavor Frag J 21(4):626–33.

Carolina C, Manzan M, Toniolo FS, Bredow E, Povh NP. 2003. Extractionof essential oil and pigments from Curcuma longa [L.] by steam distillationand extraction with volatile solvents. J Agric Food Chem 51(23):6802–7.

Carvalho RN, Moura LS, Rosa PTV, Meireles MAA. 2005. Supercriticalfluid extraction from rosemary (Rosmarinus officinalis): kinetic data, extract’sglobal yield, composition, and antioxidant activity. J Supercrit Fluids35:197–204.

Chaieb K, Hajlaoui H, Zmantar T, Kahla-Nakbi AB, Rouabhia M,Mahdouani K, Bakhrouf A. 2007. The chemical composition and biologicalactivity of clove essential oil, Eugenia caryophyllata (Syzigium aromaticum L.Myrtaceae): a short review. Phytother Res 21(6):501–6.

Chaiyasit W, McClements DJ, Decker EA. 2005. The relationship betweenthe physicochemical properties of antioxidants and their ability to inhibitlipid oxidation in bulk oil and oil-in-water emulsions. J Agric Food Chem53(12):4982–8.

Chatterjee S, Niaz Z, Gautam S, Adhikari S, Variyar PS, Sharma A. 2007.Antioxidant activity of some phenolic constituents from green pepper (Pipernigrum L.) and fresh nutmeg mace (Myristica fragrans). Food Chem101(2):515–23.

ChemBioOffice. 2008. ChemDraw Ultra 11. Available from:www.Cambridge.com. Accessed Nov 2010.

Chen HY, Lin YC, Hsieh CL. 2007. Evaluation of antioxidant activity ofaqueous extract of some selected nutraceutical herbs. Food Chem104(4):1418–24.

Chen Z. 2008. Research of antioxidative capacity in essential oils of plants.China Cond 11:40–3.

Chen ZY, Wang LY, Chan PT, Zhang Z, Chung HY, Liang C. 1998.Antioxidative activity of green tea catechin extract compared with that ofrosemary extract. J Am Oil Chem Soc 75(9):1141–5.

Cirilli R, Ferretti R, De Santis E, Gallinella B, Zanitti L, La Torre F. 2008.High-performance liquid chromatography separation of enantiomers offlavanone and 2′-hydroxychalcone under reversed-phase conditions.J Chrom 1190(1–2):95–101.

Cuvelier ME, Berset C, Richard H. 1994. Antioxidant constituents in sage(Salvia officinalis). J Agric Food Chem 42:665–9.

Deans SG, Simpson EJM. 2000. Antioxidants from Salvia officinalis. In:Kinzios SE, editor. The genus salvia. Amsterdam, the Netherlands:Harwood Academic Publishers. p 189–92.

Decker EA. 2002. Antioxidant mechanisms. In: Akoh D, Min DB, editors.Lipid chemistry. 2nd ed. New York: Marcel Dekker, Inc. p 530–2.

Defrancesco E, Trestini S. 2008. Consumers’ willingness to pay for the healthpromoting properties of organic fresh tomato. Rivista di Economia Agraria63(4):517–45.



Dixon RA, Xie DY, Sharma SB. 2005. Proanthocyanidins—a final frontierin flavonoid research? New Phys 165:9–28.

Dorman HJD, Peltoketo A, Hiltunen R, Tikkanen MJ 2003.Characterisation of the antioxidant properties of de-odourised aqueousextracts from selected Lamiaceae herbs. Food Chem 83(2):255–62.

Dorman HJD, Surai P, Deans SG. 2000. In vitro antioxidant activity of anumber of plant essential oils and phytoconstituents. J Essen Oil Res12(2):241–8.

Duh PD, Yen GC, Yen WJ, Wang BS, Chang LW. 2004. Effects of pu-erhtea on oxidative damage and nitric oxide scavenging. J Agric Food Chem52:8169–76.

Edris AE, Shalaby A, Fadel HM. 2003. Effect of organic agriculture practiceson the volatile aroma components of some essential oil plants growing inEgypt II: sweet marjoram (Origanum marjorana L.) essential oil. Flav Frag J18(4):345–51.

El-Ghorab H, Nauman M, Anjum FM, Hussain S, Nadeem M. 2010.Comparative study on chemical composition and antioxidant activity ofginger (Zingiber officinale) and cumin (Cuminum cyminum). J Agric FoodChem 58(14):8231–7.

Elmore S, Mottram DS, Enser M, Wood JD. 1999. Effect of thepolyunsaturated fatty acid composition of beef muscle on the profile ofaroma volatiles. J Agric Food Chem 47(4):1619–25.

Estevez M, Kylli P, Puolanne E, Kivikari R, Heinonen M. 2008. Oxidationof skeletal muscle myofibrillar proteins in oil-in-water emulsions: interactionwith lipids and effect of selected phenolic compounds. J Agric Food Chem56(22):10933–40.

Estevez M, Heinonen M. 2010. Effect of phenolic compounds on theformation of alpha-aminoadipic and gamma-glutamic semialdehydes frommyofibrillar proteins oxidized by copper, iron, and myoglobin. J Agric FoodChem 58(7):4448–55.

Evans G, de Challemaison B, Cox DN. 2010. Consumers’ ratings of thenatural and unnatural qualities of foods. Appetite 54(3):557–63.

FDA. 2009. Compliance Policy Guides. CPG Sec. 525.750Spices—Definitions. Available from: www.fda.gov/ICECI/ComplianceManuals/CompliancePolicyGuidanceManual/ucm074468.htm..Accessed Jan 2010.

Fasseas MK, Mountzouris KC, Tarantilis PA, Polissiou M, Zervas G 2008.Antioxidant activity in meat treated with oregano and sage essential oils.Food Chem 106(3):1188–94.

Federal Register Final Rule—62 FR 49826 September 23, 1997–FoodLabeling Regulation, Amendments; Food Regulation Uniform ComplianceDate; and New Dietary Ingredient Premarket Notification. Federal Register62(184):49825–58.

Fernandez MT, Mira ML, Florencio MH, Jennings KR. 2002. Iron andcopper chelation by flavonoids: an electrospray mass spectrometry study.J Inorg Biochem 92(2):105–111.

Fisher C. 1992. Phenolic compounds in spices. Chapter 9. In: Phenoliccompounds in food and their effects on health. ACS Symposium Series.ACS 506:118–29.

Formanek Z, Kerry JP, Higgins FM, Buckley DJ, Morrissey PA, Farkas J.2001. Addition of synthetic and natural antioxidants to α-tocopheryl acetatesupplemented beef patties; effects of antioxidants and packaging on lipidoxidation. Meat Sci 58:337–41.

Frankel EN. 1991. Recent advances in lipid oxidation. J Agric Food Chem54(4):495–511.

Frankel EN, Huang SW, Aeschbach R, Prior E. 1996. Antioxidant activityof a rosemary extract and its constituents, carnosinic acid, carnosol androsmarinic acid, in bulk oil and oil-in-water emulsion. J Agric Food Chem44:131–5.

Fukumoto L, Mazza G. 2000. Assessing antioxidant and prooxidant activitiesof phenolic compounds. J Agric Food Chem 48:3597–604.

Gardana C, Canzi E, Simonetti P. 2009. The role of diet in the metabolismof daidzein by human faecal microbiota sampled from Italian volunteers. JNut Biochem 20(12):940–7.

Gardner PT, McPhail DB, Duthie GG. 1998. Electron spin resonancespectroscopic assessment of the antioxidant potential of teas in aqueous andorganic media. J Agric Food Chem 76(2):257–62.

Geldof N, Engeseth NJ. 2002 Antioxidant capacity of honeys from variousfloral sources based on the determination of oxygen radical absorbancecapacity and inhibition of in vitro lipoprotein oxidation in human serumsamples. J Agric Food Chem 50:3050–5.

Ghiselli A, Natella F, Guidi A, Montanari I, Fantozzi P, Scaccini C. 2000.Beer increases plasma antioxidant capacity in humans. J Nutr Biochem11(2):76–80.

Giuffrida F, Destaillats F, Egart MH, Hug B, Gola PA, Skibsted LH, DionisiF. 2007. Activity and thermal stability of antioxidants by differentialscanning calorimetry and electron spin resonance spectroscopy. Food Chem101(3):1108–14.

Granato D, Castro IA, Katayama FCU. 2010. Assessing the associationbetween phenolic compounds and the antioxidant activity of Brazilian redwines using chemometrics. LWT Food Sci Technol 43:1542–9.

Granato D, Branco GF, Faria Jde A, Cruz AG. 2011. Characterization ofBrazilian lager and brown ale beers based on color, phenolic compounds,and antioxidant activity using chemometrics. J Sci Food Agric 91(3):563–71.

Grey CE, Adlercreutz P. 2006. Evaluation of multiple oxidation products formonitoring effects of antioxidants in Fenton oxidation of2′-deoxyguanosine. J Agric Food Chem 54(6):2350–8.

Gobert M, Gruffat D, Habeanu M, Parafita E, Bauchart D, Durand D. 2010.Plant extracts combined with vitamin E in PUFA-rich diets of cull cowsprotect processed beef against lipid oxidation. Meat Sci 85(4):676–83.

Gorinstein M, Leontowicz H, Leontowicz M, Namiesnik J, Najman K,Drzewiecki J, Martincova O, Katrich E, Trakhtenberg S. 2008. Comparisonof the main bioactive compounds and antioxidant activities in garlic andwhite and red onions after treatment protocols. J Agric Food Chem56(12):4418–26.

Guo Q, Richert JR, Burgess DM, Webel DE, Orr D, Blair M. 2006. Effectsof dietary vitamin E and fat supplementation on pork quality. J Anim Sci84(11):3089–99.

Guo Q, Zhao B, Li M, Shen S, Xin W. 1996. Studies on protectivemechanisms of four components of green tea polyphenols against lipidperoxidation in synaptosomes. Biochim et Biophys Acta 1304(3):210–22.

Gurdip S, Marimuthu P, Catalan C, de Lampasona MP. 2004. Chemical,antioxidant and antifungal activities of volatile oil of black pepper and itsacetone extract. J Agric Food Chem 84(14):1878–84.

Halliwell B. 1997. Antioxidants in human health and disease. Annual Reviewof Nutrition 16:33–50.

Halliwell B, Gutteridge JMC, Aruoma O. 1987. The deoxyribose method: asimple “test tube” assay for determination of rate constants for reactions ofhydroxyl radicals. Anal Biochem 165:215–9.

Halvorsen R, Carlsen M, Phillips K, Bohn S, Holte K, Jacobs D, Jr, BlonhoffR. 2006. Content of redox-active compounds (ie, antioxidants) in foodsconsumed in the United States. Am J Clin Nut 84:95–135.

Hatzidimitrioua E, Nenadisa N, Tsimidou MZ. 2007. Changes in thecatechin and epicatechin content of grape seeds on storage under differentwater activity (aw) conditions. Food Chem 105(4):1504–11

Hernandez-Hernandez E, Ponce-Alquicira E, Jaramillo-Flores ME,Guerrero-Legarreta I. 2009. Antioxidant effect of rosemary (Rosmarinusofficinalis L.) and oregano (Origanum vulgare L.) extracts on TBARS andcolour of model raw pork batters. Meat Sci 81(2):410–17.

Hillmann J. 2010. Reformulation key for consumer appeal into the nextdecade. Food Rev 37(1):14, 16, 18–9.

Hinneberg I, Dorman DHJ, Hiltunen R. 2006. Antioxidant activitiesof extracts from selected culinary herbs and spices. Food Chem 97:122–9.

Hofstrand D. 2008. Domestic perspectives on food versus fuel. AgricultureMarketing Resource Center. Available from: www.agmrc.org. Accessed Feb2010.

Hra HR, Hadolina M, Knez E, Bauman D. 2000. Comparison ofantioxidative and synergistic effects of rosemary extract with α-tocopherol,ascorbyl palmitate and citric acid in sunflower oil. Food Chem71(2):229–33.

Hu M, Skibsted LH. 2002. Kinetics of reduction of ferrylmyoglobin by(-)-epigallocatechin gallate and green tea extract. J Agric Food Chem50:2298–3003.

Huang SW, Frankel EN. 1997. Antioxidant activity of tea catechins indifferent lipid systems. J Agric Food Chem 45(8):3033–8.

Hussain I, Anwara F, Sherazi STH, Przybylski R. 2008. Chemicalcomposition, antioxidant and antimicrobial activities of basil (Ocimumbasilicum) essential oils depends on seasonal variations. Food Chem108(3):986–95.

Iacopini P, Baldi M, Storchi P, Sebastiani L. 2008. Catechin, epicatechin,quercetin, rutin, and resveratrol in red grapes: content, in vitro antioxidantactivity and interactions. J Food Comp Anal 21(8):589–98.

Jayaprakasha GK, Rao LJM, Sakariah KK. 2003. Volatile constituents fromCinnamomum zeylanicum fruit stalks and their antioxidant activities. J AgricFood Chem 5(15):4344–8.



Jayaprakasha GK, Singh RP, Sakariah KK. 2001. Antioxidant activity ofgrape seed (Vitis vinifera) extracts on peroxidation models in vitro. FoodChem 73(3):285–90.

Jayaprakashaa GK, Rao LJ, Sakariaha KK. 2006. Antioxidant activities ofcurcumin, demethoxycurcumin and bisdemethoxycurcumin. Food Chem98(4):720–4.

Jensen MT, Hansen L, Andersen HJ. 2002. Transfer of the meat aromaprecursors (dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide) fromfeed to cooked pork. LWT— Food Sci Technol 35(6):485–9.

Jirovetz L, Buchbauer G, Stoilova I, Stoyanova A, Krastanov A, Schmidt E.2006. Chemical composition and antioxidant properties of clove leafessential oil. J Agric Food Chem 54(17):6303–7.

Jo C, Ahn HJ, Son JH, Lee J, Byun MW. 2003. Packaging and irradiationeffect on lipid oxidation, color, residual nitrite content, and nitrosamineformation in cooked pork sausage. Food Control 14(1):7–12.

Joppen L. 2006. Taking out the chemistry. Food Eng Ingred 31(2):38–9, 41.

Jukic M, Politeo O, Milos M. 2006. Chemical composition and antioxidanteffect of free volatile aglycones from nutmeg (Myristica fragrans Houtt.)compared to its essential oil. Croatica Chem Acta 79:209–14.

Juliani HR, Simon JE. 2002. Antioxidant activity of basil (Ocimum spp.). In:Janick J. editor. New crops and new uses: strength in diversity. Virginia:ASHS Press. p 575–9.

Jun WJ, Han BK, Yu KW, Kim MS, Chang IS, Kim HY, Cho HC. 2001.Antioxidant effects of Origanum majorana L. on superoxide anion radicals.Food Chem 75(4):439–44.

Kapoor IPS, Singh B, Singh G, Heluani CS de, Lampasona MP, CatalanCAN. 2009. Chemical and in vitro antioxidant activity of volatile oil andoleoresins of black pepper (Piper nigrum). J Agric Food Chem57(12):5358–64.

Kerler J, Grosch W. 1996. Odorants contributing to warmed-over flavor(WOF) of refrigerated cooked beef. J Food Sci 61(6):1271–4, 1284.

Khanduja KL. 2003. Stable free radical scavenging and antiperoxidativeproperties of resveratrol in vitro compared with some other bioflavonoids.Ind J Biochem Biophys 40:416–22.

Khatun M, Eguchi S, Yamaguchi T, Takamura H, Matoba T. 2006. Effect ofthermal treatment on radical-scavenging activity of some spices. Food SciTechnol Res 12(3):178–85.

Khokhar S, Owusu-Apenten RK. 2003. Iron binding characteristics ofphenolic compounds: some tentative structure-activity relations. FoodChem 81(1):133–40.

Kiehne A, Engelhardt U. 1996. Thermospray LC-MS analysis of variousgroups of polyphenols in tea. II: chlorogenic acids, theaflavins andthearubigins. Z Leibenm untersForsch 202(4):299–302.

Kikuzaki H, Nakatani N. 2006. Antioxidant effects of some gingerconstituents. J Food Sci 58(6):1407–10.

Kim K, Cho HY. 2001. Antioxidant effects of Origanum majorana L. onsuperoxide anion radicals. Food Chem 75(4):439–44.

Kim H, Choi Y, Lim J, Paik SR, Jung S. 2009. Chiral separation of catechinby capillary electrophoresis using mon-, di-, tri-succinyl-beta-cyclodextrinas chiral selectors. Chirality 221(10):937–42.

Kondo K, Kurihara M, Fukuhara K. 2001. Mechanism of antioxidant effectof catechins. Meth Enzymol 335:203–17.

Lachman J, Sulik M, Shilla M. 2007. Comparison of the total antioxidantactivity status of Bohemian wines during the wine-making process. FoodChem 103:802–7.

Lahucky R, Nuernberg K, Kovac L, Bucko O, Nuernberg G. 2010.Assessment of the antioxidant potential of selected plant extracts—in vitroand in vivo experiments on pork. Meat Sci 85(4):779–84.

Lee AJ, Umano K, Shibamoto T, Lee KG. 2005a. Identification of volatilecomponents in basil (Ocimum basilicum L.) and thyme leaves (Thymus vulgarisL.) and their antioxidant properties. Food Chem 91(1):131–7.

Lee S, Decker EA, Faustman C, Mancini RA 2005b. The effects ofantioxidant combinations on color and lipid oxidation in n-3 oil fortifiedground beef patties. Meat Sci 70(4):683–9.

Lee J, Scagel CF. 2009. Chicoric acid found in basil (Ocimum basilicum L.)leaves. Food Chem 115:650–6.

Lee KG, Shibamoto T. 2002. Determination of antioxidant potential ofvolatile extracts isolated from various herbs and spices. J Agric Food Chem50(17):4947–52.

Lee SK, Mei L, Decker EA. 1997. Influence of sodium chloride onantioxidant enzyme activity and lipid oxidation in frozen ground pork. MeatSci 46(4):349–55.

Leelarungrayub N, Rattanapanone V, Chanarat N, Gebicki JM. 2006.Quantitative evaluation of the antioxidant properties of garlic and shallotpreparations. Nutrition 22(3):266–74.

Liang RJ, Shi SD, Ma YJ. 2010. Analysis of volatile oil composition of thepeppers from different production areas. Med Chem Res 19(2):157–65.

Lien A, He H, Pham-Huy C. 2008. Green tea and health: an overview. JFood Agric Environ 6(1):6–13.

Lugasi A, Dworschak E, Hovari J 1995. Characterization of scavengingactivity of natural polyphenols by chemiluminescence technique. Federationof the European Chemists’ Society. Proceedings of the European FoodChemists. VIII, Vienna, Austria, September. 3:639–43.

Lupea AX, Pop M, Cacig S. 2008. Structure-radical scavenging activityrelationships of flavonoids from Ziziphus and Hydrangea extracts. RevChim 59(3):309–13.

McCarthy TL, Kerry JP, Kerry JF, Lynch PB, Buckley DJ. 2001. Evaluationof the antioxidant potential of natural food/plant extracts as compared withsynthetic antioxidants and vitamin E in raw and cooked pork patties. MeatSci 58(1):45–52.

McCormick Institute Antioxidant Comparison. 2009. Curcumin: a naturalstandards review. Available from: www.mccormickscienceinstitute.com/content.cfm?ID=10480. Accessed Feb 2010.

Madsen HL, Nielsen BR, Bertelsen G, Skibsted LH. 1996. Screening ofantioxidative activity of spices. A comparison between assays based on ESRspin trapping and electrochemical measurement of oxygen consumption.Food Chem 57(2):331–7.

Mahrour A, Caillet S, Nketsia-Tabiri J, Lacroix M. 2003. The antioxidanteffect of natural substances on lipids during irradiation of chicken legs. J AmOil Chem Soc 80(7):679–84.

Marinova E, Toneva A, Yanishlieva N. 2008. Synergistic antioxidant effect ofα-tocopherol and myricetin on the autoxidation of triacylglycerols ofsunflower oil. Food Chem 106(2):628–33.

Medina I, Gallardo JM, Gonzlez MJ, Lois S, Hedges N. 2007. Effect ofmolecular structure of phenolic families as hydroxycinnamic acids andcatechins on their antioxidant effectiveness in minced fish muscle. J AgricFood Chem 55(10):3889–95.

Miguel G, Simoes M, Figueiredo AC, Barroso JG, Pedro LG, Carvalho L.2004. Composition and antioxidant activities of the essential oils of Thymuscaespititius, Thymus camphoratus and Thymus mastichina. Food Chem86(2):183–8.

Min DB, Boff JM. 2002. Chemistry and reaction of singlet oxygen in foods.Comp Rev Food Sci Food Saf 1:58–61.

Mitsumoto M, O’Grady MN, Kerry JP, Buckley DJ. 2005. Addition of teacatechins and vitamin C on sensory evaluation, colour and lipid stabilityduring chilled storage in cooked or raw beef and chicken patties. Meat Sci69(4):773–9.

Mittal R, Gupta RL. 2000. In vitro antioxidant activity of piperine. MethodsExp Clin Pharm 22(5):271–4.

Miura K, Kikuzaki H, Nakatani N. 2002. Antioxidant activity of chemicalcomponents from sage (Salvia officinalis L.) and thyme (Thymus vulgaris L.)measured by the oil stability index method. J Agric Food Chem50(7):1845–51.

Moclino I, Martinez C, Sotomayor JA, Lafuente A, Jordan MJ. 2008.Polyphenolic transmission to Segureno lamb meat from ewes’ dietssupplemented with the distillate from rosemary (Rosmarinus officinalis) leaves.J Agric Food Chem 56(9):3363–7.

Muchuweti M, Kativu E, Mupure CH, Chidewe C, Ndhlala AR, BenhuraMAN. 2007. Phenolic composition and antioxidant properties of somespices. Am J Food Technol 2(5):414–20.

Munne-Bosch S. 2005. The role of α-tocopherol in plant stress tolerance. JPlant Phys 162(7):743–8.

Murcia MA, Egea I, Romojaro F, Parras P, Jimenez AM, Martinez-Tome M.2004. Antioxidant evaluation in dessert spices compared with common foodadditives. Influence of irradiation procedure. J Agric Food Chem52(7):1872–81.

Murcia MA, Martinez-Tome M. 2001. Antioxidant activity of resveratrolcompared with common food additives. J Food Protect 64(3):379–84.

Nakatani N. 2003. Biologically functional constituents of spices and herbs. JJpn Soc Nut Food Sci 56(6):389–95.

Nakatani N, Inatani R. 1981 Structure of rosmanol a new antioxidant fromrosemary (Rosmarinus officinalis L). Agric Biol Chem 45:2385–6.

Nam KC, Ahn DU. 2003. Use of antioxidants to reduce lipid oxidation andoff-odor volatiles of irradiated pork homogenates and patties. Meat Sci63(1):1–8.



Nam KC, Min BR, Yan H, Lee EJ, Mendonca A, Wesley I, Ahn DU. 2003.Effect of dietary vitamin E and irradiation on lipid oxidation, color, andvolatiles of fresh and previously frozen turkey breast patties. Meat Sci65(1):513–21.

Nawar WF. 1996. Lipids. In: Fennema O, editor. Food chemistry. 3rd ed.New York: Marcel Dekker, Inc. p 225–320.

Naz S, Sherazi STH, Talpur FN. 2011. Changes of total tocopherol andtocopherol species during sunflower oil processing. J Am Oil Chem Soc88:127–32.

Novak I, Zambori-Nemeth E, Horvath H, Seregely Z, Kaffk K. 2003. Studyof essential oil components in different origanum species by GC and sensoryanalysis. J Acta Aliment 32(2):141–50.

Nuutila AM, Pimia RP, Aarni M, Oksman-Caldentey KM. 2003.Comparison of antioxidant activities of onion and garlic extracts byinhibition of lipid peroxidation and radical scavenging activity. Food Chem81(4):485–93.

Obana H, Furuta M, Masakazu, Tanaka Y. 2006. Detection of2-alkylcyclobutanones in irradiated meat, poultry and egg after cooking. JHealth Sci 52(4):375–82.

Okada Y, Tanaka K, Fujita I, Sato E, Okajima H. 2005. Antioxidant activityof thiosulfinates derived from garlic. Redox Rep 10(2):96–102.

Onibi GE, Scaife JR, Murray I, Fowler VR. 2000. Supplementaryα-tocopherol acetate in full-fat rapeseed-based diets for pigs: effect onperformance, plasma enzymes and meat drip loss. J Agric Food Chem80(11):1617–24.

Orhan I, Kartal M, Naz Q, Ejaz A, Yilmaz G, Kan Y, Konuklugil B, SenerB, Choudhary MI. 2007. Antioxidant and anticholinesterase evaluation ofselected Turkish Salvia species. Food Chem 103(4):1247–54.

Ozsoy N, Candoken E, Akev N. 2009. Implications for degenerativedisorders: antioxidative activity, total phenols, flavonoids, ascorbic acid,beta-carotene and beta-tocopherol in Aloe vera. Oxid Med Cell Long2(2):99–106.

Padurar I, Paduraru O, Miron A. 2008. Assessment of antioxidant activity ofBasilica herba aqueous extract—in vitro studies. Farmacia 160(4):402–8.

Papageorgiou V, Gardeli C, Mallouchos A, Papaioannou M, Komaitis M2008. Variation of the chemical profile and antioxidant behavior ofRosmarinus officinalis L. and Salvia fruticosa Miller grown in Greece. J AgricFood Chem 56(16):7254–64.

Pazos M, Lois S, Torres JL, Medina I. 2006. Inhibition of hemoglobin andiron promoted oxidation in fish microsomes by natural phenolics. J AgricFood Chem 54(12):4417–23.

Pazos M, Torres JL, Andersen ML, Skibsted LH, Medina I. 2009. Galloylatedpolyphenols efficiently reduce alpha-tocopherol radicals in a phospholipidmodel system composed of sodium dodecyl sulfate (SDS) micelles. J AgricFood Chem 57(11):5042–8.

Peschel W, Dieckmann W, Sonnenschein M, Plescher A. 2007. Highantioxidant potential of pressing residues from evening primrose incomparison to other oilseed cakes and plant antioxidants. Indust Crops Prod25(1):44–8.

Pinelo M, Manzocco L, Nunez MJ, Nicoli MC. 2004. Interaction amongphenols in food fortification: negative synergism on antioxidant capacity. JAgric Food Chem 52(5):1177–80.

Pizzale L, Bortolomeazzi R, Vichi S, Uberegger E, Conte LS. 2002.Antioxidant activity of sage (Salvia officinalis and S. fructicosa) and oregano(Origanum onites and O. indercedens) extracts related to their phenoliccompound content. J Agric Food Chem 82:1645–51.

Poiana MA, Dobrei A, Stoin D, Ghita A. 2008. The influence of viticulturalregion and the ageing process on the color structure and antioxidant profileof Cabernet Sauvignon red wines. J Food Agric Environ 6(3 4):104–8.

Pokorny J, Yanislieva N, Gordom M. 2001. Antioxidants in food—practicalapplications. Boca, Raton, Boston, New York, Washington, D.C.:Woodhead Publishing, CRC Press. p 380.

Politeo O, Jukic M, Milos M. 2010. Comparison of chemical compositionand antioxidant activity of glycosidically bound and free volatiles from clove(Eugenia caryophyllata Thunb.). J Food Biochem 34(1):129–41.

Potapovich AI, Kostyuk VA. 2003. Comparative study of antioxidantproperties and cytoprotective activity of flavonoids. Biochem (Moscow)68(5):514–9.

Prior RL, Hoang H, Gu L, Wu X, Bacchiocca M, Howard L,Hampsch-Woodill M, Huang D, Ou B, Jacob R. 2003. Assays forhydrophilic and lipophilic antioxidant capacity (oxygen radical absorbancecapacity [ORACFL]) of plasma and other biological and food samples. JAgric Food Chem 51:3273–9.

Priyadarsini KI, Maity DK, Naik GH, Kumar MS, Unnikrishnan MK, SatavJG, Mohan H. 2003. Role of phenolic O-H and methylene hydrogen onthe free radical reactions and antioxidant activity of curcumin. Free RadBiol Med 35:475–84.

Rababah TM, Ereifej KI, Al-Mahasneh MA, Ismaeal K, Hidar AG, Yang W.2008. Total phenolics, antioxidant activities, and anthocyanins of differentgrape seed cultivars grown in Jordan. Int J Food Prop 11(2):472–9.

Radovanovic A, Radovanovic B, Jovancicevic B. 2009. Free radicalscavenging and bacterial activities of southern Serbian red wines. FoodChem 117:326–31.

Reblova Z. 2006. The effect of temperature on the antioxidant activity oftocopherols. Eur J Lipid Sci Technol 108(10):858–63.

Rehman Z, Salariya AM, Habib F. 2003. Antioxidant activity of gingerextract in sunflower oil. J Agric Food Chem 83(7):624–9.

Richheimer SL, Bernart MW, King GA, Kent MC, Bailey DT. 1996.Antioxidant activity of lipid-soluble phenolic diterpenes from rosemary. JAm Oil Chem Soc 73(4):507–14.

Richter J, Schellenberg I. 2007. Comparison of different extraction methodsfor the determination of essential oils and related compounds from aromaticplants and optimization of solid-phase microextraction/gas chromatography.Anal Bioanal Chem 387(6):2207–17.

Rivero Perez MD, Muniz P, Gonzalez Sanjose ML. 2008. Contribution ofanthocyanin fraction to the antioxidant. Food Chem Toxico 46(8):2815–9.

Rochat S, Chaintreau A. 2005. Carbonyl odorants contributing to thein-oven roast beef top note. J Agric Food Chem 53(24):9578–85.

Rojas M, Brewer S. 2007. Effect of natural antioxidants on oxidative stabilityof cooked, refrigerated beef and pork. J Food Sci 72:S282–8.

Rojas M, Brewer MS. 2008a. Effect of natural antioxidants on oxidativestability of frozen, vacuum-packaged beef and pork. J Food Qual3(12):173–88.

Rojas MC, Brewer MS. 2008b. Consumer attitudes towards issues in foodsafety. J Food Saf 28(1):1–22.

Ross L, Barclay RC, Vinqvist MR, Mukai K, Goto H, Hashimoto Y,Tokunaga A, Uno H. 2000. On the antioxidant mechanism of curcumin:classical methods are needed to determine antioxidant mechanism andactivity. Orig Let 2(18):2841–3.

Ruberto G, Baratta MT, Deans SG, Dorman HJD. 2000. Antioxidant andantimicrobial activity of Foeniculum vulgare and Crithmum maritimumessential oils. Planta Med 66:687–93.

Sarma AD, Sreelakshmi Y, Sharma R. 1997. Antioxidant abilityof anthocyanins against ascorbic acid oxidation. Phytochem 45(4):671–4.

Sasse A, Colindres P, Brewer MS. 2009. Effect of natural and syntheticantioxidants on oxidative stability of cooked, frozen pork patties. J Food Sci74(1):S30–5.

Schmidt E, Bail S, Buchbauer G, Stoilova I, Krastanov A, Stoyanova A,Jirovetz L. 2008. Chemical composition, olfactory evaluation andantioxidant effects of the essential oil of Origanum majorana L. from Albania.Nat Prod Comm 3(7):1051–6.

Schmidt E, Jirovetz L, Buchbauer G, Eller GA, Stoilova I, Krastanov A,Stoyanova A, Geissler M. 2006. Composition and antioxidant activities ofthe essential oil of cinnamon (Cinnamomum zeylanicum Blume) leaves fromSri Lanka. J Essen Oil-Bearing Plants 9(2):170–82.

Schwarz K, Bertelsen G, Nissen LR, Gardner PT, Heinonen MI, Huynh-BaAH, Lambelet P, McPhail D, Skibsted LH, Tijburg L. 2001. Investigation ofplant extracts for the protection of processed foods against lipid oxidation.Comparison of antioxidant assays based on radical scavenging, lipidoxidation and analysis of the principal antioxidant compounds. Eur FoodRes Technol 212:319–28.

Shahidi F, Wanasundara PK. 1992. Phenolic antioxidants. Crit Rev Food SciNut 32(1):67–103.

Shan B, Cai Y-Z, Brooks JD, Corke H. 2007. The in vitro antibacterialactivity of dietary spice and medicinal herb extracts. Int J Food Microbiol117(1):112–9.

Shan B, Cai YZ, Sun M, Corke H. 2005. Antioxidant capacity of 26 spiceextracts and characterization of their phenolic constituents. J Agric FoodChem 53(2):7749–59.

Si-Ahmed K, Tazerouti F, Badjah-Hadj-Ahmed AY, Aturki Z, D’Orazio G,Rocco A, Fanali S. 2010. Analysis of hesperetin enantiomers in humanurine after ingestion of blood orange juice by using nano-liquidchromatography. J Pharm Biomed Anal 51(1):225–9.

Simitzis PE, Deligeorgis SG, Bizelis JA, Dardamani A, Theodosiou I, FegerosK. 2008. Effect of dietary oregano oil supplementation on lamb meatcharacteristics. Meat Sci 79(2):217–23.



Singh G, Maurya S, de Lampasona MP, Catalan CAN. 2007. A comparisonof chemical, antioxidant and antimicrobial studies of cinnamon leaf and barkvolatile oils, oleoresins and their constituents. Food Chem Tox45(9):1650–61.

Sloan AE. 1999. Top ten trends to watch and work on for the millennium.Food Technol 53(8):40–8, 51–8.

Smet K, Raes K, Huyghebaert G, Haak L, Arnouts S, Smet S de. 2008. Lipidand protein oxidation of broiler meat as influenced by dietary naturalantioxidant supplementation. Poultry Sci 87(8):1682–8.

Soares DG, Andreazza AC, Salvador M. 2003. Sequestering ability ofbutylated hydroxytoluene, propyl gallate, resveratrol, and vitamins C and Eagainst ABTS, DPPH, and hydroxyl free radicals in chemical and biologicalsystems. J Agric Food Chem 51(4):1077–80.

Srinivasan O, Parkin KL, Fennema O, editors. 2008. Fennema’s foodchemistry. 4th ed. Boca Raton, Fla.: CRC Press. p 1144.

Srinivasan K. 2007. Black pepper and its pungent principle-piperine: areview of diverse physiological effects. Crit Rev Food Sci Nut 47(8):735–48.

Sroka Z, Cisowski W. 2003. Hydrogen peroxide scavenging, antioxidant andanti-radical activity of some phenolic acids. Food Chem Tox 41(6):753–8.

Stashenko EE, Puertas MA, Martinez JR. 2002. SPME determination ofvolatile aldehydes for evaluation of in-vitro antioxidant activity. AnalBioanal Chem 373(1/2):70–4.

Suhaj M. 2006. Spice antioxidants isolation and their antiradical activity: areview. J Food Comp Anal 19(6–7):531–7.

Swigert KS, McKeith FK, Carr TR, Brewer MS, Culbertson M. 2004.Effects of dietary vitamin D3, vitamin E, and magnesium supplementationon pork quality. Meat Sci 67(1):81–6.

Takemoto JK, Remsberg CM, Yanez JA JA, Vega-Villa KR, Davies NM.2008. Stereospecific analysis of sakuranetin by high-performance liquidchromatography: pharmacokinetic and botanical applications. J ChromAnalyt Technol 75(1):136–41.

Teissedre P, Waterhouse A. 2000. Inhibition of oxidation of humanlow-density lipoproteins by phenolic substances in different essential oilsvarieties. J Agric Food Chem 48:3801–5.

Tepe B, Sokmen M, Akpulat HA, Sokmen A. 2006. Screening of theantioxidant potentials of six Salvia species from Turkey. Food Chem95(2):200–4.

Thomas RH, Bernards MA, Drake EE, Guglielmo CG. 2010. Changes inthe antioxidant activities of seven herb- and spice-based marinating saucesafter cooking. J Food Comp Anal 23(3):244–52.

Thorsen MA, Hildebrandt KS. 2003. Quantitative determination of phenolicditerpenes in rosemary extracts: aspects of accurate identification. J Chrom9(5):119–25.

Tiwari V, Shankar R, Srivastrava J, Vankar PM. 2006. Change in antioxidantactivity of spices—turmeric and ginger on heat treatment. J Environ FoodChem 5(2):1313–7.

Tomaino A, Cimino F, Zimbalatti V, Venuti V, Sulfaro V, de Pasquale A,Saija A. 2005. Influence of heating on antioxidant activity and the chemicalcomposition of some spice essential oils. Food Chem 89(4):549–54.

Touns MS, Ouerghemmi I, Wannes WA, Ksouri R, Zemn H, Marzouk B,Kchou ME. 2009. Valorization of three varieties of grape. Industrial CropsProd 30(2):292–6

Trojakova L, Reblova Z, Nguyen HTT, Pokorny J. 2001. Antioxidantactivity of rosemary and sage extracts in rapeseed oil. J Food Lipids 8:1–13.

Tyler V. 1993. The honest herbal. New York: The Haworth Press, Inc. p139–41.

Uchiyama N, Kim IH, Kikura-Hanajiri R, Kawahara N, Konishi T, Goda Y.2008. HPLC separation of naringin, neohesperidin and their C-2 epimers incommercial samples and herbal medicines. J Pharm Biomed Anal46(5):864–9.

United States Consumer Product Safety Commission. 1992. Final report:study of aversive agents. Available from: www.cpsc.gov/library/foia/foia99/os/aversive.pdf. Accessed Feb 2011.

Uri N. 1961. Mechanism of antioxidation. In: Lundber WO, editor.Autoxidation and antioxidants. New York: Interscience. p 133–9.

Ursini F, Rapuzzi I, Toniolo R, Tubaro F, Bontempelli G. 2001.Characterization of antioxidant effect of procyanidins. Meth Enzymol335:338–50.

USDA. 2010. USDA Database for the oxygen radical absorbance capacity(ORAC) of selected foods. Release 2. U.S. Department of Agriculture.ARS. Beltsville, MD. Available from: www.ars.usda.gov/

SP2UserFiles/Place/12354500/Data/.../ORAC_R2.pdf. Accessed May2010.

Vega JD, Brewer MS. 1995. Detectable odor thresholds of selected lipidoxidation compounds in a meat model system. J Food Sci 60(3):592–5.

Vega-Villa KR, Yanez JA, Remsberg CM, Ohgami Y, Davies NM. 2008.Stereospecific high-performance liquid chromatographic validation ofhomoeriodictyol in serum Yerba Santa (Eriodictyon glutinosum). J PharmBiomed Anal 46(5):971–4.

Vera RR, Chane-Ming J. 1999. Chemical composition of the essential oil ofmarjoram (Origanum majorana L.) from Reunion Island. Food Chem66(2):143–5.

Viuda-Martos M, Ruiz-Navajas Y, Fernandez-Lopez J, Perez-Alvarez JA.2010. Effect of adding citrus fibre washing water and rosemary essential oilon the quality characteristics of a bologna sausage. LWT Food Sci Tech43(6):958–63.

Wanatabe Y, Nakanashi H, Goto N, Otsuka K, Kimura T, Adachi S. 2010.Antioxidative properties of ascorbic acid and acyl ascorbates in ML/Wemulsion. J Am Oil Chem Soc 85:1475–80.

Wang W, Wu N, Zu YG, Fu YJ. 2008. Antioxidative activity of Rosmarinusofficinalis L. essential oil compared to its main components. Food Chem108(3):1019–22.

Wen LC, Wen YC, SungChuan W, KuangHway Y. 2009. DPPH free-radicalscavenging activity, total phenolic contents and chemical compositionanalysis of forty-two kinds of essential oils. J Food Drug Anal 17(5):386–95.

Williams P, Markoska J, Chachay V, McMahon A. 2009. ‘Natural’ claims onfoods: a review of regulations and a pilot study of the views of Australianconsumers. Food Aust 61(9):383–9.

Wills TM, Mireles DeWitt CA, Sigfusson H. 2007. Improved antioxidantactivity of vitamin E through solubilization in ethanol: a model study withground beef. Meat Sci 76(2):308–15.

Wojdyło A, Oszmianski J, Czemerys R. 2007. Antioxidant activity andphenolic compounds in 32 selected herbs. Food Chem 105(3):940–9.

Xiao JB, Suzuki M, Jiang XY, Chen XQ, Yamamoto K, Ren FL, Xu M.2008. Influence of B-ring hydroxylation on interactions of flavonols withbovine serum albumin. J Agric Food Chem 56(7):2350–6.

Xu CM, Zhang YL, Wang J, Lu JA. 2010. Extraction, distribution andcharacterisation of phenolic compounds and oil in grapeseeds. Food Chem122(3):688–94.

Yancey EJ, Grobbel JP, Dikeman ME, Smith JS, Hachmeister KA, ChambersEC, Gadgil P, Milliken GA, Dressle E. 2006. Effects of total iron,myoglobin, hemoglobin, and lipid oxidation of uncooked muscles on liveryflavor development and volatiles of cooked beef steaks. Meat Sci 73:680–6.

Yanagimoto K, Ochi H, Lee K, Shibamoto T. 2003. Antioxidative activitiesof volatile extracts from green tea, oolong tea, and black tea. J Agric FoodChem 51(25):7396–401.

Yanez JA, Andrews PK, Davies NM. 2007. Methods of analysis andseparation of chiral flavonoids. J Chrom Anal Tech Biomed Life Sci 848(2):159–81.

Yanez JA, Remsberg CM, Miranda ND, Vega-Villa KR, Andrews PK,Davies NM. 2008. Pharmacokinetics of selected chiral flavonoids:hesperetin, naringenin and eriodictyol in rats and their content in fruitjuices. Biopharm Drug Dispos 29(2):63–82.

Yanez JA, Teng XW, Roupe KA, Davies NM. 2005. Stereospecifichigh-performance liquid chromatographic analysis of hesperetin inbiological matrices. J Pharm Biomed Anal 37(3):591–5.

Yanishieva NV, Marinova E, Pokorny J. 2006. Natural antioxidants fromherbs and spices. Eur J Lipid Sci Technol 108:776–93.

Yetella RR, Min DB. 2008. Quenching mechanisms and kinetics of troloxand ascorbic acid on the riboflavin-photosensitized oxidation of tryptophanand tyrosine. J Agric Food Chem 56(22):10887–92.

Yeum KJ, Beretta G, Krinsky NI, Russell RM, Aldini G. 2009. Synergisticinteractions of antioxidant nutrients in a biological model system. Nut25(7/8):839–46.

Yong J, Hun K, Sung YP, W, JC, Seong SY, Young JY. 2000. Identificationof irradiation-induced volatile flavor compounds in chicken. J Korean SocFood Sci Nut 29(6):1050–6.

Yoo KM, Lee CH, Lee H, Moon BK, Lee CY. 2008. Relative antioxidantand cytoprotective activities of common herbs. Food Chem 106(3):929–36.



Youdim KA, Deans SG, Finlayson HJ 2002. The antioxidant properties ofthyme (Thymus zygis L.) essential oil: an inhibitor of lipid peroxidation and afree radical scavenger. J Essen Oil Res 14(3):210–5.

Yu XC, Wang X, Adelberg J, Barron FH, Chen Y, Chung HY. 2008.Evaluation of antioxidant activity of curcumin-free turmeric (Curcuma longaL.). Chapter 14. In: Oil and identification of its antioxidant constituents.Functional food and health. ACS Ser. 993:152–64.

Zhang J, Jinnai S, Ikeda R, Wada M, Hayashida S, Nakashima K. 2009. Asimple HPLC-fluorescence method for quantitation of curcuminoids and itsapplication to turmeric products. Analytical Sciences 25. Available from:http://naosite.lb.nagasakiu.ac.jp/dspace/bitstream/10069/22006/1/AnalSci25_385.pdf. Accessed Feb 2010.


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