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AOCS Mission StatementAOCS advances the science and technology of oils, fats, surfactants and related materials, enriching the lives of people everywhere.

AOCS Books and Special Publications Committee W. Byrdwell, Chairperson, USDA, ARS, BHNRC, FCMDL, Beltsville, MarylandN.T. Dunford, Oklahoma State University, OklahomaD.G. Hayes, University of Tennessee, Knoxville, TennesseeV. Huang, Yuanpei University of Science and Technology, TaiwanG. Knothe, USDA, ARS, NCAUR, Peoria, IllinoisD.R. Kodali, University of Minnesota, Minneapolis, MinnesotaG.R. List, USDA, NCAUR-Retired, Consulting, Peoria, IllinoisR. Moreau, USDA, ARS, ERRC, Wyndmoor, PennsylvaniaW. Warren Schmidt, Surfactant Consultant, Cincinnati, OhioP. White, Iowa State University, Ames, IowaN. Widlak, ADM Cocoa, Milwaukee, WisconsinR. Wilson, Oilseeds & Biosciences Consulting, Raleigh, North Carolina

Copyright © 2015 by AOCS Press, Urbana, IL 61802. All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means without written permission of the publisher.

ISBN 978-1-630670-44-3 (print) ISBN 978-1-630670-45-0 (.epub)ISBN 978-1-630670-46-7 (.mobi)

Library of Congress Cataloging-in-Publication DataPolar lipids : biology, chemistry, and technology / editors, Moghis Ahmad, Xuebing Xu. pages cm ISBN 978-1-63067-044-3 (print : alk. paper)—ISBN 978-1-63067-045-0 (epub)— ISBN 978-1-63067-046-7 (mobi) 1. Lipids. 2. Oils and fats—Analysis. 3. Lecithin. 4. Chemistry, Organic. I. Ahmad, Moghis, editor. II. Xu, Xuebing, 1962– editor. QP751.P635 2015 572'.57— dc23 2015007162

Printed in the United States of America19 18 17 16 15 5 4 3 2 1

The paper used in this book is acid-free, and falls within the guidelines established to ensure permanence and durability.

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v

Contents

Preface vii

List of Abbreviations ix

chapter 1 1

Soybean Lecithin: Food, Industrial Uses, and Other Applications G.R. List

chapter 2 35

Rice Bran Lecithin: Compositional, Nutritional, and Functional CharacteristicsRam Chandra Reddy Jala and R.B.N. Prasad

chapter 3 57

Sunflower LecithinEstefania N. Guiotto, Mabel C. Tomás, and Bernd W.K. Diehl

chapter 4 77

Palm PhospholipidsWorawan Panpipat and Manat Chaijan

chapter 5 91

Milk and Dairy Polar Lipids: Occurrence, Purification, and Nutritional and Technological PropertiesThien Trung Le, Thi Thanh Que Phan, John Van Camp, and Koen Dewettinck

chapter 6 145

Phosphatidylserine: Biology, Technologies and Applications Xiaoli Liu, Misa Shiihara, Naruyuki Taniwaki, Naoki Shirasaka, Yuta Atsumi, and Masatoshi Shiojiri

chapter 7 185

Phenolipids as New Antioxidants: Production, Activity, and Potential ApplicationsDerya Kahveci, Mickaël Laguerre and Pierre Villeneuve

chapter 8 215

Sugar Fatty Acid EstersYan Zheng, Minying Zheng, Zonghui Ma, Benrong Xin, Ruihua Guo, and Xuebing Xu


vi ■ Contents

chapter 9 245

Production and Utilization of Natural PhospholipidsWillem van Nieuwenhuyzen

chapter 10 277

Autoxidation of Plasma Lipids, Generation of Bioactive Products and Their Biological RelevanceArnis Kuksis and Waldemar Pruzanski

chapter 11 349

Lysophospholipids: Advances in Synthesis and Biological SignificanceMoghis U. Ahmad, Shoukath M. Ali, Ateeq Ahmad, Saifuddin Sheikh, and Imran Ahmad

chapter 12 391

NMR of Polar LipidsBernd W.K. Diehl

chapter 13 439

Polar Lipid Profiling by Supercritical Fluid Chromatography/Mass Spectrometry MethodTakayuki Yamada, Yumiko Nagasawa, Kaori Taguchi, Eiichiro Fukusaki, and Takeshi Bamba

chapter 14 463

Omega-3 PhospholipidsKangyi Zhang

About the Editors 495

Contributors 497

Index 501


215

8Sugar Fatty Acid Esters

Yan Zheng, Minying Zheng, Zonghui Ma, Benrong Xin, Ruihua Guo, and Xuebing Xu ■ Wilmar (Shanghai) Biotechnology Research and Development

Center Co., Ltd., Shanghai, China

Introduction

Sugar fatty acid esters, usually called sugar esters (SEs), are non-ionic and biode-gradable surfactants. Because of their good stabilizing and conditioning properties, they have broad applications in the food, pharmaceutical, detergent, agricultural, fine chemical, and personal care industries (H-Kittikun et al., 2012; Magg, 1984; Naka-mura et al., 1997). SEs can be synthesized by an esterification reaction between sugar/sugar alcohols (e.g., sucrose, fructose, glucose, sorbitol, xylitol) and nonpolar fatty acids. The higher substitution esters (HSEs), hexa, hepta, and octa, find use as fat replacers. The lower s ubstitution esters (LSEs), mono-, di-, and tri-esters, find use as oil-in-water (O/W) as well as water-in-oil (W/O) emulsifiers.

In one typical example, sucrose esters are non-ionic compounds synthesized by esterification of fatty acids (or natural glycerides) with sucrose. Sucrose (α-D-glucopyranosyl β-D-fructofuranoside) is a polyhydric alcohol with eight hydroxyl groups (Figure 8.1): three primary hydroxyls (C6, C1', C6') and five secondary hy-droxyls. The three primary hydroxyls on the sucrose molecule are the most reactive and are the easiest to substitute with fatty acids, forming mono-, di-, and tri-esters. Hence, compounds ranging from mono- to octa- esters are theoretically possible, and different ester substitutions can determine the properties of the resultant su-crose esters.

LSEs used as emulsifiers, which depends on their hydrophilic-lipophilic balance (HLB), has been widely researched. For HSEs, the most extensively studied and publicized of the fat substitutes is olestra (Olean, Procter & Gamble). It is prepared

Figure 8.1 Structure of sucrose.


216 ■ Y. Zheng et al.

from the reaction of sucrose with long-chain fatty acid methyl esters. Digestive enzymes do not release the fatty acids, so olestra is noncaloric (Mattson and Volpenhein, 1972).

This chapter will focus on various methods of synthesis of SEs, physiochemical properties, and the uses as emulsifiers and fat replacers.

Properties of Sugar Fatty Acid Esters

Physicochemical Properties

It is well known that the usage of fatty acid esters in various areas is based on their special physicochemical properties. SEs are non-ionic surface-active agents consisting of sugar as a hydrophilic group and fatty acids as lipophilic groups. The carbon chain length and nature of the sugar head group, together with the many possibilities for linkage between the hydrophilic sugar head group and the hydrophobic alkyl chain, contribute to the unique physicochemical properties of sugar fatty acid esters (El-Laithy et al., 2011). Depending on the composition, SEs exist as solids, waxy materials, or liquids (Szüts and Szabó-Révész, 2012). Depending on the degree of esterification, SEs decrease the surface tension of water. Therefore, they can exhibit different surface-active properties including HLB values, critical micelle concentration (CMC), emulsifying stability, and foaming ability. In addition, the sugar esters have special thermal properties.

Hydrophilic–Lipophilic Balance

Hydrophilic–lipophilic balance (HLB) is the balance of the size and strength of the hydrophilic and lipophilic moieties of a surfactant molecule. The HLB scale ranges from 0 to 20. In the range of 3.5 to 6.0, surfactants are more suitable for use in W/O emulsions. Surfactants with HLB values in the 8 to 18 range are most commonly used in O/W emulsions (Griffin, 1949). The longer the fatty acid chains in the SEs and the higher the degree of esterification, the lower the HLB value (Figure 8.2).

Micelle Formation and Critical Micelle Concentration

Due to their amphipathic structure, sugar esters in aqueous solutions tend to form thermodynamically stable molecular aggregates called micelles. Micelles begin to form at a specific concentration called critical micelle concentration (CMC), which is depen-dent on the surfactant structure and experimental conditions. Below the CMC, the surfactants are solubilized as monomers in the solution. Once the CMC is reached, all additional surfactants that have been added are employed either in the formation of new micelles or for promoting the growth of the aggregates (Könnecker et al., 2011).

The glucose molecule has a highly hydrophilic head group, and when the degree of glucosidation increases, the surface-active properties will decrease. Research (Joshi et al., 2007) shows that, in the micelle, a longer hydrocarbon chain results in a larger


Sugar Fatty Acid Esters ■ 217

hydrocarbon region. Furthermore, the CMC decreases as the alkyl chain length in-creases, so that at a given total surfactant concentration, a longer chain surfactant generally has a larger concentration of surfactant in the micellar state.

The temperature also affects the micellar formation and surface activity, and the SEs are very sensitive to temperature change. The increase of the temperature leads to larger micelle sizes and lower CMC (Molina-Bolívar and Ruiz, 2008).

Emulsification Properties

The surface-active properties of sugar fatty acid esters are derived from the original hydrophilic group of sugar/sugar alcohol and the original lipophilic group of fatty ac-ids. By varying the degree of substitution or the fatty acid chain lengths, wide ranges of functionality can be obtained. Emulsification is the most important function of sugar esters.

16

11

7

3

1

Ester Composition (%)

HLB

100 20 30 40 50 60 70 80 90 100

Mono

MonoMono

Mono

Mono Di

Di

Di

Di

Tri

Tri

Tri

Tri PentaTetra

Tetra

Hexa Hapta

Mono

Figure 8.2 Ester compositions and HLB values of SEs. HLB: hydrophilic-lipophilic balance; SE: sugar ester.



Sugar fatty acid esters with three or fewer fatty acids reduce the surface tension of water. For example, sophorolipid esters can effectively reduce the surface ten-sion of water to values below 38.7 mN/m–1 (Zhang et al., 2004). Moreover, Neta et al. (2012) found that fructose esters, synthesized from oleic acid, fructose, and ethanol by CALB (Candida antarctica lipase B), are able to reduce the surface ten-sion to 35.8 mN/m–1 and also to stabilize an emulsion (emulsification indexes [EI] between 54.4% and 58.4%).

Foaming Ability

Many food products consist of foams, which are thermodynamically unstable sys-tems. Foam stability can be improved by the addition of SEs, which decreases the surface tension. A lower surface tension facilitates the enlargement of the air–water interfacial area, resulting in higher foam ability (Table 8.A).

Coalescence of bubbles is also a key factor in the stability of foams. The coales-cence of air bubbles is greatly influenced by the type and concentration of SEs pres-ent in the solution. In pure water, air bubbles coalesce almost instantly. However, coalescence is not instantaneous in aqueous solutions of SEs. The main factors that determine the coalescence time in these solutions are the surface excess concentration of the surfactant and the repulsive surface forces (steric forces). So, the SEs stabilize the films mainly by steric force (Samanta and Ghosh, 2011).

On the other hand, some of the SEs, especially sucrose laurate, do not typically form interfaces with high viscoelasticity. Instead, they stabilize the interface by the

Table 8.A Effects of SEs with Different HLB Values on Foam Characteristics

EmulsifierMono-Ester

% HLB Value

Surface Tensiona (mN/m)

Foam Heightb (ml)

0 min 5 min

Sucrose laurate 70 15 28.5 127 1245Sucrose palmitate 75 16 34.0 29 36Sucrose stearate 70 15 34.5 31 29Sucrose stearate 50 11 36.7 12 9Sucrose stearate 30 6 46.8 4 2Distilled water — — 72.8 — —

Note: SE: sugar fatty acid ester; HLB: hydrophilic–lipophilic balance. All tested in 0.1% solutions.aDu Nouy method.bRoss and Miles method.



Gibbs-Marangoni mechanism. This mechanism relies on rapid surface diffusion of sucrose laurate that will reduce surface concentration gradients that may develop as a result of deformations of the interface (Kempen et al., 2013). During diffusion, su-crose laurate drags along some of the continuous phase. This slows down drainage of liquid from the films, which will increase foam stability.

Thermal Properties

The thermal properties of SEs can be used to evaluate their applicability in hot-melt technology. The melting points of most sugars are high, but SEs, depending upon their degree of esterification, have melting points of 40–79 °C and are quite stable to heat; hence, they can be employed to prepare solid dispersions by the melt tech-nology. It is very important to know the thermal behavior of these materials so that the changes in the base materials can be predicted during storage and technological processes such as the preparation of solid dispersions by melting (Szüts et al., 2007). Evaluation of the thermal properties of sugar fatty acid esters can also help to observe and analyze the time-dependent solid-state changes.

SEs with high or moderate HLB values have a glass transition temperature (Tg) instead of a melting point. They soften during heating, whereas SEs with low HLB values melt and then quickly recrystallize from their melts. However, the original structure does not return for SEs with high, moderate, or low HLB values; after melting and solidification, their melts continuously change. In addition, the SEs with various HLB values can also be used to influence (increase or decrease) the rate of dissolution of other materials, and hence to change the development of the effect. Due to their low melting points, they are promising carriers for the melting method.

Biological Properties

The most prominent biological property of SEs is the antimicrobial property. Con-ley and Kabara (1973) conducted several antimicrobial experiments using SEs. They determined the minimal inhibitory concentration of a series of sucrose fatty acid esters against gram-negative and gram-positive organisms. Gram-positive organisms were affected. Sucrose esters had greater inhibitory effect than the free fatty acids ex-cept lauric acid. The antimicrobial activity of sucrose esters comes from the interac-tion of the esters with cell membranes of bacteria, causing autolysis. The lytic action is assumed to be due to stimulation of autolytic enzymes rather than to actual solu-bilization of cell membranes of bacteria (Wang, 2004). However, although the effec-tiveness of fatty acids increased when esterified, the spectrum of antimicrobial action of the esters is narrower when compared with the free acids. In addition, very similar



organisms do not have the same susceptibility to comparable sucrose esters (Marshall and Bullerman, 1996). Marshall and Bullerman (1986) examined the antimicrobial properties of six sucrose esters substituted to different degrees with a mixture of fatty acids (palmitic and stearic). Antimycotic activity was detected against several mold species from Aspergillus, Penicillium, Cladosporium, and Alternaria. The least- substituted sucrose ester was the most active in reducing mold growth. Investigations in vitro and using refrigerated beef showed that sucrose fatty acid esters were also active against Escherichia coli O157, L. monocytogenes, Staph. aureus, and psychrotro-phic spoilage microorganisms (Hathcox and Beuchat, 1996; Kabara, 1993; Monk and Beuchat, 1995; Monk et al., 1996).

Fructose esters could be used as antimicrobial agents that suppressed the cell growth of Streptococcus mutans, a causative organism of dental caries. Among the dif-ferent carbohydrate esters, fructose laurate showed the highest growth inhibitory ef-fect (Watanabe et al., 2000).

In food hygiene, biofilms were also a very important potential hazard and a source of microbial contamination of foods. Furukawa et al. (2010) investigated the effects of food additives on biofilm formation by food-borne pathogenic bacteria. They found that sucrose monomyristate and sucrose monopalmitate significantly in-hibited biofilm formation by Staphylococcus aureus and Escherichia coli at a low con-centration (0.001% w/w). The addition of sucrose monopalmitate at the early growth stage of S. aureus exhibited a strong inhibitory effect, suggesting that the ester inhib-ited the initial attachment of the bacterial cells to the abiotic surface.

Production of Sugar Fatty Acid Esters

Chemical Synthesis

There have been a significant number of publications on sugar fatty acid esters from the mid-1950s, in particular the LSEs that have been commercially manufactured and used as emulsifiers since the early 1960s.

The initial synthesis of LSEs by transesterification used dimethyl formamide (DMF) as the mutual solvent for solubilizing sugar and free fatty acid. This process was first commercialized by Dai-Nippon Sugar Manufacturing Co., Ltd., in Japan in the late 1960s to produce sucrose fatty acid esters as food additives (Ryoto, 1987; Yamada et al., 1980). Sucrose fatty acid esters manufactured by this process were not approved for use in the United States because of the odor and toxic materials present in the prod-uct. Osipow et al. (1956) described the first commercial process for the preparation of sucrose fatty acid ester from methyl ester in DMF. A relatively safer process, known as the Nebraska-Snell process, was developed that involved reacting a microemulsion of sucrose in propylene glycol as solvent with the fatty acid methyl ester in the presence of potassium carbonate as the catalyst (Osipow and Rosenblatt, 1967).



A lot of workers have modified the process to avoid using a toxic solvent. A solvent-free interesterificaiton process was developed by Feuge et al. (1970) at the Southern Regional Research Center (SRRC), and this was licensed to Ryoto Co. in Japan (now Mitsubishi-Kasei Food Corporation). This process involved the reaction between molten sucrose (mp 185 °C) and fatty acid methyl esters in the presence of lithium, potassium, and sodium soaps as solubilizers and catalysts at temperatures between 170 °C and 187 °C. A combination of lithium oleate with sodium or potas-sium oleate at 25% of total soap, based on the weight of sugar, gave the best sucrose fatty acid ester product. The drawback of this process is that molten sucrose is rapidly degraded to a black tarry mass at 170–187 °C. In both solvent and solvent-free pro-cesses, distillation is often required to remove the unreacted methyl esters, fatty acids, and alcoholic byproducts (Akoh, 1994).

Other studies on the syntheses of sucrose fatty acid esters have also been report-ed. Lemieux and McInnes (1962) reported a preparative method for the synthesis of sucrose mono-esters in anhydrous DMF, of which 80% of the total product was monoester and 20% di-ester based on the amount of methyl ester that reacted. Jones (1981) described a process for preparing mono- and di-esters of sucrose from sucrose and alkenyl ester of fatty acid in a polar aprotic solvent.

Another hot topic is that of chemical synthesis of HSEs. They are mixtures of sucrose esters formed by chemical interesterification of sucrose with six to eight fatty acids. The HSE commonly known as olestra (Olean) is manufactured from satu-rated and unsaturated fatty acids of chain length C12 and higher, obtained from conventional edible fats and vegetable oils (Shieh et al., 1996). The first step of the process is methylation of fatty acids. The second step is transesterification of sucrose and fatty acid methyl ester using catalysts, such as alkali metals or their soaps, under anhydrous conditions and high vacuum. The resulting crude olestra product is puri-fied by washing, bleaching, and deodorizing to remove free fatty acids and odors, fol-lowed by distillation to remove unreacted fatty acid methyl esters and sucrose esters with low degrees of fatty acid substitution.

Rizzi and Taylor (1978) described a solvent-free two-stage reaction sequence for synthesizing HSEs. In the first stage, sucrose and fatty acid methyl ester (FAME) with a mole ratio of 1:3 were reacted in the presence of potassium soaps to form a homogenous melt in 2–3.5 hours. The product of this stage contained mainly esters of sucrose with a low degree of substitution (DS = 1 – 3). In the second stage, excess FAME and more NaH were added and reacted for an additional 6 hours to produce HSEs in yields up to 90%. This process was modified by Hamm (1984) by adding methyl oleate at the beginning of the reaction and sucrose and NaH in increments, and HSEs with a DS of 4–8 were obtained in 42% theoretical yield.

Akoh and Swanson (1990) reported an optimized synthesis of HSEs that gave yields between 99.6% and 99.8% of the purified HSEs based on the initial weight of sucrose octa-acetate (SOAC). This was a one-stage, solvent-free process involving



admixing of sucrose octa-acetate, 1–2% sodium metal as catalyst, and FAME of veg-etable oils in a three-neck reaction flask prior to application of heat. Formation of a one-phase melt was achieved 20–30 minutes after heat was applied. High yields of HSEs were obtained at temperatures as low as 105 °C and synthesis times as short as 2 hours by pulling a vacuum of 0–5 mm Hg pressure.

Enzymatic Synthesis

In recent years, utilization of enzymes as biocatalysts for preparing SEs has attracted great attention because of growing consumer demand for green processes and prod-ucts (Table 8.B on p. 224). The enzymatic process will bring the advantage of the high specificity and regioselectivity of the reaction at a lower temperature and an eas-ier downstream process, which will generate various products with controlled struc-ture and functionality. On the other hand, due to the steric hindrance, only LSEs can be achieved through the enzymatic method. In the following section, solvents’, enzymes’, and substrates’ properties and how they affect each other on the productiv-ity of enzymatic synthesis of LSEs are briefly discussed.

Solvents are essential for LSE production due to the different solubilities of sugar and fatty acids. Looking for a suitable organic medium for enzymatic synthesis of LSEs requires full consideration of solvent toxicity to the biocatalyst and the solubility of substrates. Proteases such as substilisin can maintain catalytic activity in strongly polar solvents like dimethylformamide (DMF) (Pedersen et al., 2003). Ferrer et al. (2002) synthesized 6-O-lauroyl sucrose from sucrose and vinyl laurate using a lipase in mixed solvents of tert-amyl alcohol and Dimethylsulfoxide (DMSO) to improve substrates solubility, and the yield to 6-O-lauroyl sucrose was up to 70%. Degn and Zimmer-mann (2001) reported the synthesis of myristate ester of different carbohydrates us-ing Novozyme 435; the production rate of myristyl glucose was improved from 222 to 1212 mmol g−1 h−1 by changing the solvent from pure tert-butanol to a mixture of tert- butanol and pyridine. Besides toxicity and solubility, parameters such as the sol-vent dielectric constant (Affleck et al., 1992), polarity and partition coefficient (Lu et al., 2008), as well as electron acceptance index (Valivety et al., 1994) have been used to study the effect different solvents on the rate of lipase-mediated synthesis of SEs.

Besides organic solvents, a new kind of solvents called ionic liquids (ILs) are being increasingly used in lipase-mediated synthesis of SEs for their nonvolatile character and thermal stability. They exhibit excellent physicochemical characteristics, includ-ing the ability to dissolve polar, nonpolar, organic, inorganic, and polymeric com-pounds. It was also observed that ILs enhanced the reactivity, selectivity, and stability of enzymes. ILs containing dicyanamide anion were found to be able to dissolve considerable amount of glucose and sucrose (Forsyth and Macfarlane, 2003). Park and Kazlauskas (2001) synthesized 10 ILs and investigated the acylation of sugar with



vinyl acetate catalyzed by Candida antarctica lipase B (CALB). Their result showed that enzymes’ catalytic efficiency and selectivity could be changed by using different ILs. Lee et al. (2008) observed that enzyme activities in ILs were highly enhanced by using a supersaturated solution under ultrasound irradiation in lipase-catalyzed es-terifications of sugar with vinyl laurate or lauric acid, but the stability of the enzyme in ILs was not influenced by ultrasound irradiation. Although these studies about ILs mainly deal with the synthesis of monosaccharide esters, these samples provide use-ful insights considered to be appropriate for an application of enzymatic synthesis of HSEs in the future.

Lipase (triacylglycerol acylhydrolase, EC 3.1.1.3) has been widely used in en-zymatic synthesis of LSEs for its properties in nonaqueous media. To avoid the side effect of water and enhance the activity and regioselectivity of a given lipase, immobi-lization and modification technologies are widely studied. Cao et al. (1999) reported the conversion in the synthesis of 6-O-glucose palmitate increased with decreasing hydrophilicity of the support.

Tsuzuki et al. (1999) found that use of a detergent-modified lipase powder af-forded greater yields of SEs compared to the use of untreated powder of the same lipase. Ferrer et al. (2002) evaluated the Thermomyces lanuginosus lipase (TLL) im-mobilized by three methods: adsorption on polypropylene (Accurel EP100), covalent attachment to Eupergit C, and silica-granulation. The lipase adsorbed on Accurel showed an extraordinary initial activity and the highest selectivity to 6-O-lauroyl su-crose was found with granulated lipase. Other methods like preparing surfactant-lipase complex (Maruyama et al., 2002), using different ionic liquids as coating materials (Mutschler et al., 2009), as well as rational design of lipases (Magnusson et al., 2005) to improve lipase’s property have been fully discussed.

Fatty acids of different chain length and lipase from different sources used to synthesize SEs have a great influence on the efficiency of a catalyzing process. Some lipases exhibit a high selectivity for long- and medium-chain fatty acids, whereas oth-ers are selective toward short and branched fatty acids. Research showed that the conversion increased with increasing chain length of the fatty acid when the reac-tion was catalyzed by Hog pancreas lipase (HPL). When the synthesis reaction was catalyzed by TLL, the conversion decreased with increasing chain length of the acid. The conversion is nearly independent of the chain length of the acid for the reaction catalyzed by Novozym 435 (Kumar et al., 2005). In the case of synthesis of sucrose 6-mono-esters, TLL is more effective than lipase from CALB, which is more interest-ing for the synthesis of the corresponding 6,6'-di-esters (Ferrer et al., 2005). The type of acyl donor also can affect the reaction. Among the methyl, ethyl, and vinyl ester substrates, vinyl ester is extensively used because its byproduct, vinyl alcohol, can be converted to acetaldehyde irreversibly, thereby increasing the yield of the desired ester (Yadav and Trivedi, 2003).


224

Tab

le 8

.B E

nzy

mat

ic S

ynth

esis

of

SEs

by

Lip

ases

in V

ario

us

Org

anic

So

lven

ts

Sub

stra

tes

Enzy

mes

Solv

ents

Tim

e (h

)Pr

od

uct

sY

ield

Ref

eren

ces

Acy

l acc

epto

rA

cyl d

on

or

D-f

ruct

ose

Stea

ric

acid

Lip

ozy

me

SP 3

82te

rt-B

uta

no

l46

2 o

r 6-

O-s

tear

ate

fru

cto

se8.

6%C

han

g a

nd

Sh

aw (

2009

)

D-F

ruct

ose

PFA

DN

ovo

zym

435

Ace

ton

e72

6-O

-pal

mit

oyl

-α-D

-fr

uct

op

yran

ose

38.8

%C

hai

yaso

et

al. (

2006

)

D-G

alac

tose

6-O

-pal

mit

oyl

-α-D

-g

luco

pyr

ano

se6.

8%

D-G

luco

se6-

O-p

alm

ito

yl-α

-D-

glu

cop

yran

ose

76.0

%

a-M

eth

yl-g

luco

se6-

O-p

alm

ito

yl-α

-D-

glu

cop

yran

ose

78.0

%

Glu

cose

Lau

ric

acid

TLL

tert

-am

yl

alco

ho

l:DM

SO20

6-O

-lau

royl

glu

cose

98.0

%Fe

rrer

et

al.

(200

5)

D-G

luco

seL-

Ala

nin

eLi

po

zym

e IM

20 R

ML

CH

2Cl2

:DM

F (9

0:10

, v/v

; 40º

C)

72M

ixtu

re o

f m

on

o-e

ster

s2.

0%So

mas

hek

ar

and

Div

akar

(2

007)

D-F

ruct

ose

Mix

ture

of

di-

este

rs17

.0%

Mix

ture

of

mo

no

-est

ers

6.0%

Lact

ose

Mix

ture

of

di-

este

rs6.

0%

Mix

ture

of

mo

no

-est

ers

14.0

%

Sucr

ose

Mix

ture

of

mo

no

-est

ers

8.0%

Fru

cto

seO

leic

aci

dN

ovo

zym

435

Eth

ano

l37

.8M

ixtu

re o

f es

ters

88.4

%N

eta

et a

l. (2

011)

Sucr

ose

Do

dec

ano

icC

ALB

ILs

Mix

ture

of

mo

no

-est

ers

25.0

%Li

u e

t al

. (2

005)

D-G

luco

seM

yris

tic

acid

No

vozy

m 4

35te

rt-b

uta

no

l: p

yrid

ine

(55:

45,

v/v)

24M

yris

tyl g

luco

se34

mg

/m

LD

egn

an

d

Zim

mer

man

n

(200

1)D

-Fru

cto

seM

yris

tyl f

ruct

ose

22.3

μ

mo

l/m

in.g

Mal

tose

Myr

isty

l mal

tose

1.9

μm

ol/

min

.g

Mal

totr

iose

Myr

isty

l mal

totr

iose

ND

Cel

lob

iose

Myr

isty

l cel

lob

iose

ND

Sucr

ose

Myr

isty

l su

cro

seN

D

Lact

ose

Myr

isty

l lac

tose

ND

α- a

nd

β-D

- G

luco

pyr

ano

sid

eM

yris

tyla

- D

-glu

cop

yran

osi

de

26.9

μ

mo

l/m

in.g

Sucr

ose

Vin

yl

lau

rate

Met

allo

pro

teas

e Th

erm

oly

sin

(B

acill

us

ther

mo

pro

teo

lyti

cus)

Dim

eth

ylsu

lfo

xid

e (D

MSO

)12

2-O

-Lau

royl

-su

cro

se53

.0

nm

ol/

min

.g

Ped

erse

n e

t al

. (20

02)

No

te: D

MSO

: dim

eth

ylsu

lfo

xid

e; P

FAD

: pal

m f

atty

aci

d d

isti

llate

s; N

D: n

ot

det

ecte

d; C

ALB

: Can

did

a an

tarc

tica

lip

ase

B; T

LL: T

her

mo

myc

es la

nu

gin

osu

s lip

ase;

RM

L: R

hiz

om

uco

r m

ieh

ei li

pas

e; D

MF:

dim

eth

ylfo

rmam

ide;

SE

: su

gar

est

er.


225

Tab

le 8

.B E

nzy

mat

ic S

ynth

esis

of

SEs

by

Lip

ases

in V

ario

us

Org

anic

So

lven

ts

Sub

stra

tes

Enzy

mes

Solv

ents

Tim

e (h

)Pr

od

uct

sY

ield

Ref

eren

ces

Acy

l acc

epto

rA

cyl d

on

or

D-f

ruct

ose

Stea

ric

acid

Lip

ozy

me

SP 3

82te

rt-B

uta

no

l46

2 o

r 6-

O-s

tear

ate

fru

cto

se8.

6%C

han

g a

nd

Sh

aw (

2009

)

D-F

ruct

ose

PFA

DN

ovo

zym

435

Ace

ton

e72

6-O

-pal

mit

oyl

-α-D

-fr

uct

op

yran

ose

38.8

%C

hai

yaso

et

al. (

2006

)

D-G

alac

tose

6-O

-pal

mit

oyl

-α-D

-g

luco

pyr

ano

se6.

8%

D-G

luco

se6-

O-p

alm

ito

yl-α

-D-

glu

cop

yran

ose

76.0

%

a-M

eth

yl-g

luco

se6-

O-p

alm

ito

yl-α

-D-

glu

cop

yran

ose

78.0

%

Glu

cose

Lau

ric

acid

TLL

tert

-am

yl

alco

ho

l:DM

SO20

6-O

-lau

royl

glu

cose

98.0

%Fe

rrer

et

al.

(200

5)

D-G

luco

seL-

Ala

nin

eLi

po

zym

e IM

20 R

ML

CH

2Cl2

:DM

F (9

0:10

, v/v

; 40º

C)

72M

ixtu

re o

f m

on

o-e

ster

s2.

0%So

mas

hek

ar

and

Div

akar

(2

007)

D-F

ruct

ose

Mix

ture

of

di-

este

rs17

.0%

Mix

ture

of

mo

no

-est

ers

6.0%

Lact

ose

Mix

ture

of

di-

este

rs6.

0%

Mix

ture

of

mo

no

-est

ers

14.0

%

Sucr

ose

Mix

ture

of

mo

no

-est

ers

8.0%

Fru

cto

seO

leic

aci

dN

ovo

zym

435

Eth

ano

l37

.8M

ixtu

re o

f es

ters

88.4

%N

eta

et a

l. (2

011)

Sucr

ose

Do

dec

ano

icC

ALB

ILs

Mix

ture

of

mo

no

-est

ers

25.0

%Li

u e

t al

. (2

005)

D-G

luco

seM

yris

tic

acid

No

vozy

m 4

35te

rt-b

uta

no

l: p

yrid

ine

(55:

45,

v/v)

24M

yris

tyl g

luco

se34

mg

/m

LD

egn

an

d

Zim

mer

man

n

(200

1)D

-Fru

cto

seM

yris

tyl f

ruct

ose

22.3

μ

mo

l/m

in.g

Mal

tose

Myr

isty

l mal

tose

1.9

μm

ol/

min

.g

Mal

totr

iose

Myr

isty

l mal

totr

iose

ND

Cel

lob

iose

Myr

isty

l cel

lob

iose

ND

Sucr

ose

Myr

isty

l su

cro

seN

D

Lact

ose

Myr

isty

l lac

tose

ND

α- a

nd

β-D

- G

luco

pyr

ano

sid

eM

yris

tyla

- D

-glu

cop

yran

osi

de

26.9

μ

mo

l/m

in.g

Sucr

ose

Vin

yl

lau

rate

Met

allo

pro

teas

e Th

erm

oly

sin

(B

acill

us

ther

mo

pro

teo

lyti

cus)

Dim

eth

ylsu

lfo

xid

e (D

MSO

)12

2-O

-Lau

royl

-su

cro

se53

.0

nm

ol/

min

.g

Ped

erse

n e

t al

. (20

02)

No

te: D

MSO

: dim

eth

ylsu

lfo

xid

e; P

FAD

: pal

m f

atty

aci

d d

isti

llate

s; N

D: n

ot

det

ecte

d; C

ALB

: Can

did

a an

tarc

tica

lip

ase

B; T

LL: T

her

mo

myc

es la

nu

gin

osu

s lip

ase;

RM

L: R

hiz

om

uco

r m

ieh

ei li

pas

e; D

MF:

dim

eth

ylfo

rmam

ide;

SE

: su

gar

est

er.



The solubility of the substrates is affected by the concentration of the other sub-strate because dissolution of a substrate affects the polarity of the reaction medium; thus, the molar ratio of the two substrates has a great impact on the esterification pro-cess. For example, for glucose stearic acid ester synthesis using CALB as the catalyst, an excess of the fatty acid in the reaction medium led to a significant increase of sugar ester synthesis. On the other hand, the sugar ester yield was reduced by decreasing the chain length of the fatty acid in the reaction involving glucose (Yan et al., 2001). The esteri-fication of fructose in tert-amyl alcohol was favored by an excess of short-chain fatty acids; however, an excess of long-chain fatty acids decreased the conversion rate (Soul-tani et al., 2001). In general, the conversion rate of lipase-catalyzed transesterification involving fatty acids with less than 10 carbons can be improved by supplying an excess of fatty acid. On the other hand, a lower molar ratio of fatty acid to sugar is preferable if the reaction involves longer fatty acids, because a high concentration of a nonpolar fatty acid decreases the solubility of sugar in the reaction medium (Gumel et al., 2011).

Applications of Sugar Fatty Acid Esters

As we know, there are many kinds of sugar fatty acid esters such as sucrose esters, maltose esters, fructose esters, raffinose esters, and so forth. The most widely used sugar esters, sucrose esters, are synthesized by esterification of fatty acids (or natural glycerides) with sucrose. In this part, we mainly focus on the application of various sucrose esters that have been approved for use in the food, pharmaceutical, and cos-metic industries.

Applications in the Food Industry

Without any safety or laws and regulations issues, only sucrose esters have broad ap-plications in the food industry (Nakamura, 1997; Watanabe et al., 2000). During food processing, sucrose esters could be utilized as food emulsifiers, wetting and dis-persing agents, and antibiotics. Moreover, they could retard staling, solubilize flavor oils, improve organoleptic properties in bakery and ice cream formulations, and could be used as fat stabilizers during the cooking of fats (Banat et al., 2010).

EmulsifiersSucrose esters have been manufactured commercially as food emulsifiers since the early 1960s. Their wide range of HLB, depending on degree of esterification of fatty acids and sucrose, provides ultimate application of sucrose esters to each product type.

Megahed (1999) prepared sucrose fatty acid esters as food emulsifiers and evalu-ated their surface active and emulsification properties. They compared the surface tension, interfacial tension, and HLB of sucrose esters with different fatty acids. Re-sults indicated the presence of unsaturated fatty acid moieties (oleic), and the hydro-



philic carbohydrate backbone in the carbohydrate polyesters contributed to a much lower surface tension. Based on their emulsion stability experiments, they found that sucrose laurate and palmitate have high O/W emulsion stability.

The synthesis of long-chain fatty acid sucrose mono-esters was one of the first major achievements of the Sugar Research Foundation (Polat and Linhardt, 2001). Ariyaprakai et al. (2013) investigated the interfacial and emulsifier properties of su-crose monostearate in comparison with Tween 60 in coconut milk emulsions. They found that sucrose monostearate was slightly better in lowering the interfacial tension between the coconut oil and water interface. The complex between coconut protein and sucrose monostearate seemed to be an emulsifying membrane that could better protect coconut milk emulsions from heat and freeze damage.

Surfactant in Colloidal Delivery SystemsAnother important application of sucrose esters surfactant is the manufacture of food-grade colloidal delivery systems, namely microemulsions and nanoemulsions. Micro-emulsions and nanoemulsions are composed of oil, surfactant, and water and can be easily fabricated from food ingredients via relatively simple operation procedures, such as agitation, mixing, shearing, and homogenization. However, the widespread applica-tion of microemulsions and nanoemulsions in many food products is limited by several technical and practical problems, including the limited number of food-grade surfac-tants available for preparing and stabilizing these systems (Kralova and Sjoblom, 2009). Consequently, sucrose ester surfactants seem to be a good alternative for the manufac-ture of such colloidal delivery systems. Edris and Malone (2011) used sucrose laurate (containing 78–81% of sucrose monolaurate) to deliver flavoring to food or beverages without using organic solvents. The sucrose laurate surfactant exerted a good emulsi-fication property in this food nano-delivery system. Sucrose monopalmitate was also investigated in its capability of forming colloidal dispersions, in which lemon oil was the oil phase (Rao and McClements, 2011). This study provided important information for optimizing the application of sucrose mono-esters to form colloidal dispersions in food and beverage products. Fanun (2009) reported the properties of microemulsions manufactured from sucrose monolaurate, sucrose dilaurate, and peppermint oil (edible oil suitable for food, pharmaceutical, and cosmetics applications).

Fat SubstitutesFat substitutes are compounds that physically and chemically resemble triglycerides and are stable to cooking and frying temperatures. Sugar or sugar alcohol fatty acid esters such as sucrose polyester (olestra), sorbitol polyester, and raffinose polyester are among the most studied fat substitutes. Olestra is industrialized by Procter & Gamble. Because olestra is not hydrolyzed by fat-splitting enzymes in the small intes-tine, it is not absorbed from the small intestine into blood and tissues, and therefore provides no energy that can be utilized by the body (Jandacek, 2012).


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