alice

, A-CEsta

Rafupelitan

a r t i c l e i n f o a b s t r a c t

Eight chia essential oil-in-water fresh emulsions (E) variations were prepared using biopolymers blends

ity of chia essential oil can be enhanced through microencapsula-tion. Microencapsulation by spray-drying is widely used in thefood industry for the preparation of dry stable additives such asessential oils and avours (Fuchs et al., 2006; Kha et al., 2010). Itinvolves the emulsication of a core material, usually a lipid, with

et al., 2001; Danviriyakul et al., 2002; Barbosa et al., 2005), andon microcapsule morphometric characterization (Quintanilla-Carvajal et al., 2011). A stable emulsion with smaller oil dropletscan increase the retention of volatiles and shelf-life of encapsu-lated oil products through reduction of unencapsulated oil at thesurface of powder particles (Minemoto et al., 2002; Soottitantawatet al., 2003, 2005). Liu et al. (2000, 2001) found that the stability ofemulsion was a controlling factor for hydrophobic avours reten-tion (d-limonene, ethyl propionate and ethyl butyrate). Somebiopolymers used as wall material for lipid encapsulation byspray-drying include gum Arabic (GA) (Shaikh et al., 2006), whey

Corresponding author. Address: Departament of Chemical Engineering, Facultyof Chemistry, Universidad Autnoma del Estado de Mxico, Paseo Coln esq. PaseoTollocan s/n, Col. Residencial Coln, C.P. 50120, Toluca, State of Mexico, Mexico.Tel.: +52 722 2173890; fax: +52 722 2175109.

Journal of Food Engineering 111 (2012) 102109

Contents lists available at

Journal of Food

lsE-mail address: cpereza@uaemex.mx (C. Prez-Alonso).1. Introduction

Chia (Salvia hispanica L.) is a native seed of southern Mexico andwas among the principal crops grown by ancient Mesoamericancultures. The fatty acids of chia oil are highly unsaturated, beinglinoleic (1726%) and a-linolenic (5057%) acids the main compo-nents (Ayerza, 1995; lvarez-Chvez et al., 2008). Omega-3 (x-3)unsaturated fatty acids are nutritionally important for good healthand are especially benecial for individuals suffering from coro-nary heart disease, diabetes, and immune response disorders(Djordjevic et al., 2004; McClements et al., 2007).

The main compounds of the chia oil are volatiles and chemicallyunstable in the presence of oxygen, light, moisture and heat. Stabil-

a dense solution of wall material such as proteins, gums, carbohy-drates, and atomization and drying of the emulsion (Fuchs et al.,2006; Gharsallaoui et al., 2007; Charcosset, 2009; Pulido andBeristain, 2010). An area of research of increasing interest is theuse of biopolymers blends as wall materials that may allow to in-crease the encapsulation efciency and shelf life of microcapsules(Jimenez et al., 2006; Prez-Alonso et al., 2008, 2009). The selectionof wall material will inuence the emulsion stability during its for-mation and upon the drying process affecting the characteristics ofthe resulting microcapsules (R, 1998). Emulsication is one of theimportant and critical steps in spray-drying microencapsulation offood oils, as the emulsion stability and droplet size play a key rolein the encapsulation efciency during and after the process (LiuArticle history:Received 29 August 2011Received in revised form 5 December 2011Accepted 28 January 2012Available online 6 February 2012

Keywords:Chia essential oilBiopolymers blendsMicrocapsulesFresh and reconstituted O/W emulsionsEncapsulation efciency0260-8774/$ - see front matter 2012 Elsevier Ltd. Adoi:10.1016/j.jfoodeng.2012.01.020whey protein concentrate (WPC) with mesquite gum (MG) or gum Arabic (GA), core to wall materialratios (Co:Wa) of 1:2 and 1:3, and total solids contents (TSC) of 30 and 40 wt%. All E variations displayedvolume-weighted mean size (d4,3) droplet sizes that fell within 2.32 and 3.35 lm and rates of dropletcoalescence (kC) of 108 s1. E variations were spray-dried and the resulting microcapsules (M) hadd4,3 falling within the range of 13.1728.20 lm. The encapsulation efciency (EE) was higher than 70%for all M, but those obtained from E with lower TSC and higher Co:Wa displayed higher EE and lowersurface oil, independently of M particle size. The reconstituted emulsions (RE) exhibited signicantlyhigher d4,3 and kC values of the same magnitude as E variations.

2012 Elsevier Ltd. All rights reserved.Spray-dried encapsulation of chia essentiprotein concentrate-polysaccharide matr

Dulce Anahi Rodea-Gonzlez a, Julian Cruz-Olivares a

Mara Eva Rodrguez-Huezo c, Eduardo Jaime VernonaDepartamento de Ingeniera Qumica, Facultad de Qumica, Universidad Autnoma delToluca, Estado de Mxico, MexicobDepartamento de Biotecnologa, Universidad Autnoma Metropolitana-Iztapalapa, SancDepartamentos Divisin de Ingeniera Qumica y Bioqumica, Tecnolgico de Estudios SdDepartamento de Ingeniera de Procesos e Hidrulica, Universidad Autnoma MetropoD.F., Mexico

journal homepage: www.ell rights reserved.oil (Salvia hispanica L.) in wheys

nglica Romn-Guerrero b,arter d, Csar Prez-Alonso a,do de Mxico, Paseo Coln esq. Paseo Tollocan s/n, Col. Residencial Coln, C.P. 50120,

ael Atlixco 186, Col. Vicentina, C.P. 09340, Mxico, D.F., Mexicoriores de Ecatepec, Estado de Mxico, Mexicoa-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Edicio T-247, C.P. 09340, Mxico,

SciVerse ScienceDirect

Engineering

evier .com/locate / j foodeng

f Fooprotein concentrate (WPC) (Hogan et al., 2001a) and mesquite gum(MG) (Beristain and Vernon-Carter, 1994). Several studies haveestablished that MG, the exudate from Prosopis laevigata, possessesemulsifying and microencapsulating properties (Rodrguez-Huezoet al., 2004), forms dense lms upon drying that limit oxygen dif-fusion through its matrix (Bez-Gonzlez et al., 2004), comparableor superior to those of GA, the exudate from Acacia senegal, whichis considered as a benchmark commodity worldwide (Dickinson,2003). Chemically, MG is very similar to GA. Both gums are highlybranched complex heteropolyelectrolytes formed principally byL-arabinose and D-galactose, and minor proportions of 4-O-methyl-D-glucuronate, and L-rhamnose, differing only in the ratiobetween these residues, being of 2:4:1:1 for MG, and 4:2:1:1 forGA, respectively (Ray et al., 1995; Romn-Guerrero et al., 2009).Also both gums contain a small amount of protein (2.04.8% formesquite gum, and from 1.0% to 2.0% for gum Arabic). This proteinfraction is responsible for the emulsifying and lm forming proper-ties of both gums (Trejo-Espino et al., 2010). WPC is made up by adiverse group of proteins that nd functionality in a wide variety offood applications. WPC proteins have globular structure and stay insolution over a wide range of pH, can be denatured by heat and ex-hibit heat induced gelation (Morr and Ha, 1993). It is known thatproteins, polysaccharides, and their blends may enhance the func-tional properties of food formulations (foams, emulsions, anddispersions) (Benichou et al., 2002). Vernon-Carter et al. (1996) re-ported that the stability against droplet coalescence of marigoldoleoresin-in-water emulsions containing blends of mesquite gumand gum Arabic had a synergistic effect providing higher stabilityand viscosity to the emulsions than either gum on its own.Beristain and Vernon-Carter (1995) reported that gum Arabic-mesquite gum blends had very good orange peel oil encapsulationability. Canola oil-in water cloudy emulsions obtained usingGA-whey protein isolate blends showed enhanced stability againstsignicant droplet size increase than either biopolymer on its own(Klein et al., 2010). Hogan et al. (2001ac) shows that microencap-sulation efciency of soy oil with milk proteins and carbohydrateblends was inversely proportional to emulsion droplet size. Liuet al. (2000, 2001) found that the stability of emulsion was acontrolling factor for hydrophobic avours retention (d-limonene,ethyl propionate and ethyl butyrate).

Microencapsulated essential fatty acids have been used increas-ingly as ingredients in functional foods (breads, cake mixes, gela-tine desserts, pet foods, breakfast cereal, etc.). Gkmen et al.(2011) developed functional breads containing encapsulatedOmega-3 fatty acids.

The objective of this work was to determine the inuencebinary biopolymers blends of whey protein concentrate withgum Arabic or mesquite gum on the: (i) droplet size and stabilityof the fresh chia essential oil-in-water emulsions; (ii) encapsula-tion efciency of the microcapsules obtained by spray-drying ofthe emulsions; and (iii) droplet size and stability of the rehydratedemulsions.

2. Materials and methods

2.1. Materials

Chia seeds were provided by farmers from the region of Atlixco,State of Puebla, Mexico. A Tamer hydraulic press (Model PT-20,Shanghai, China) tted with a 40 cm long and 10 cm diameterplunger was used for cold pressing the chia seeds for obtainingthe chia essential oil (CEO). Maximum pressure applied by thepiston was 8.8 108 N/m2 to the piston, at room temperature

D.A. Rodea-Gonzlez et al. / Journal o(20 C). Trace amounts of seed were removed from CEO using acloth lter, and ltered CEO was stored in amber bottles at atemperature of 4 C until required.Composition of CEO was determined by gas chromatography(Agilent 6890, model G1530A, CA, USA) equipped with an autosampler (model 7683B), a ame ionization detector (FID) and aCP-Sil 88 column (100 m 0.25 mm 0.39 mm). Initial columntemperature was 90 C, and a heating ramp of 1.5 C/min was useduntil 225 C was achieved. Helium was used as carrier gas at a owrate of 0.7 mL/min. CEO was made up by 20 compounds, with oleic,linoleic, a-linolenic acids accounting for 7.7%, 19.1% and 58.3% ofCEO, and the rest of the compounds in concentrations lower than3.1%. This composition was very similar to that reported bylvarez-Chvez et al. (2008).

Whey protein concentrate (WPC) with 80% protein on dry basiswas purchased from Hilmar Ingredients (Hilmar, CA, USA); mes-quite gum (MG) was hand collected in the form of tear drops fromProsopis laevigata trees in the Mexican State of San Luis Potosi andpuried as indicated by Vernon-Carter et al. (1996); and gumArabic (Acacia senegal) (GA) purchased from Industria Ragar, S.A.de C.V. (Mexico City, Mexico), were used as emulsifying/wall mate-rials in this work. Deionized water was used in all the experiments,and sodium azide (Hycel de Mexico, S.A. de C.V., Mexico City,Mexico) was used as preservative. 2-propanol and petroleum etherwere purchased from SigmaAldrich Quimica, S.A. de C.V. (Toluca,State of Mexico, Mexico).

2.2. Methods

2.2.1. Preparation of the oil-in-water emulsionsAqueous stock solutions (25% w/w) of WPC-GA or WPC-MG in

67:33 ratiowith0.3%w/wsodiumazide (to prevent theproliferationof microorganisms) were prepared, and kept overnight in a shakingwater bath at room temperature (20 C) towarrant a full hydrationof the biopolymer molecules (Jafari et al., 2007a). In order to obtainoil-in-water emulsions (O/W) variations with different core to wallmaterial ratios (Co:Wa) in dry basis and total solids contents, the req-uisite amount of CEO was poured drop wise into the requisiteamount of biopolymers blends solutions (WPC-MG or WPC-GA).Emulsication was done with an Ultra-Turrax T50 homogenizer(IKA-WERKEWorks Inc., Wilmington, NC, USA) at 6400 r.p.m. dur-ing 10 min. The emulsionsweremaintained in an icedwater bath inorder to keep the temperature below 30 C. The codes and formula-tions of the resulting fresh emulsions (E) are given in Table 1.

2.2.2. Viscosity of emulsionsA Kinexus Pro rheometer (Malvern Instruments Ltd., Worcester-

shire, UK), with a cone-plate geometry, in which the rotating conewas 40 mm in diameter, and cone angle of 4was used for perform-ing the viscosity measurements. Samples of E were carefully placedin the measuring system. The apparent viscosity of each emulsionwas determined at 25 C by applying an increasing shear rate from0.01 to 100 s1, and viscosity-shear rate plots were obtained. Theviscosity of CEO was also determined as explained above.

2.2.3. Preparation of microcapsules by spray-dryingThe different fresh emulsions variations were spray-dried using

a Nichols/Niro spray-drier (Turbo Spray PLA, NY, USA), using a feedrate of 40 mL min1 and an inlet and oulet air temperatures of135 5 C, and 80 5 C respectively, with an atomization pressureof 4 bar (Pavn-Garca et al., 2011). The resulting microcapsules(M) and the reconstituted emulsions (RE) obtained by redispersingthe microcapsules variations in water were coded as indicated inTable 1.

2.2.4. Morphology of microcapsules by scanning electronic microscopy

d Engineering 111 (2012) 102109 103(SEM) analysisA JSM-5800LV model scanning electron microscope (Jeol Co.

Ltd., Tokyo, Japan) was used to investigate the microstructural

ns (R

stit

,WPC

,WPC

,WPC

,WPC

,WPC

,WPC

,WPC

,WPC

: Co= to

f Fooproperties of the spray-dried encapsulated powders. The sampleswere placed on the SEM stubs using a two-sided adhesive tape(Ted Pella, Redding, California, USA), and subsequently coated withaurum using a magnetron sputter coater (Denton Vacuum Model,USA), at 100 militorrs and 15 mA. The coated samples were thenanalysed using SEM operating at an accelerating voltage of 25 kV.The micrographs representing the microstructure of the M weretaken by the instruments software installed on a PC connectedto the system (Prez-Alonso et al., 2009).

2.2.5. Fresh and reconstituted emulsions droplet and microcapsuleparticle sizes

The volume-weighted mean size (d4,3) of the E and RE emul-sions, and of the M was determined by laser diffraction using aMalvern Mastersizer 2000 (Malvern Instruments Ltd., Malvern,Worcestershire, UK). The RE were obtained by rehydrating M inthe requisite amount of water to equal the TSC of E. Mixing wasdone with a magnetic stirrer for 30 min at room temperature(20 C).

M were dispersed in 2-propanol (refractive index 1.376) for theparticle size analysis, while E and RE were dispersed in water.

Additionally, the stability of E and RE was determined by deter-mining the rate of droplet coalescence (kC) as follows (Ruz-Ramoset al., 2006):

NtN0

ekCt 1

where Nt is the number concentration of droplets at time t, N0 is thenumber concentration of freshly formed droplets (time = 0), and kCis the rate constant, which is related to the probability of the inter-droplet lm (interfacial layer) rupturing in time t (Darling, 1987).When the volume of emulsion droplets remains constant, that is,no oiling-off occurs in the emulsions, the relationship between theemulsion droplet number, N, and the mean volume average dropletdiameter, d30 = (Rnd3/Rn)1/2, where n1, n2, n3 . . . , are the number ofdroplets with diameters d1, d2, d3 . . . , is given by (Sherman, 1969):

Table 1Composition of the fresh emulsions (E), microcapsules (M) and reconstituted emulsio

Emulsions code Microcapsules code Recon

E1:2,WPC-MG,30 M1:2,WPC-MG,30 RE1:2E1:3,WPC-MG,30 M1:3,WPC-MG,30 RE1:3E1:2,WPC-MG,40 M1:2,WPC-MG,40 RE1:2E1:3,WPC-MG,40 M1:3,WPC-MG,40 RE1:3E1:2,WPC-GA,30 M1:2,WPC-GA,30 RE1:2E1:3,WPC-GA,30 M1:3,WPC-GA,30 RE1:3E1:2,WPC-GA,40 M1:2,WPC-GA,40 RE1:2E1:3,WPC-GA,40 M1:3,WPC-GA,40 RE1:3

E, M, and RE are followed by subindexes in the following order and that stand for(WPC = whey protein concentrate; MG = mesquite gum; GA = gum Arabic); and TSC

104 D.A. Rodea-Gonzlez et al. / Journal o43p d3;0

2

3N constant 2

The relative number of emulsion droplets can then be obtainedfrom (Ye et al., 2004):

NtN0

d3;0t0d3;0tt

33

If the kinetic plots of ln (Nt/N0) versus t for the emulsions give astraight line, then the slope is kC (Ruz-Ramos et al., 2006).

2.2.6. Moisture content of the microcapsulesMoisture content of the M was determined using a moisture

balance (Model MB45, Ohaus Corporation, Parsippany, NJ, USA).Approximately 3 g of M were placed in an aluminum moisturepan and dried at 95 C until a constant weight was achieved.2.2.7. Surface and total CEO content in microcapsulesSurface CEO in M was determined according to Jimenez et al.

(2006). Five grams of M were dispersed in petroleum ether for10 min using slight stirring in order to avoid the M deterioration,then the solvent was decanted and was dried in a forced convec-tion drying oven (Riossa, model E-51, Mexico City, Mexico) at6080 C until constant weight was achieved.

Total CEO was obtained by dispersing 5 g of M in 10 mL ofpetroleum ether and was sonicated (Sonics Vibra Cell VCX130 PB, Sonics & Materials, Inc., Newtown, CT, USA) at 70% ampli-tude and frequency of 20 kHz for 10 min. Then they were extractedwith a Soxhlet extraction system during 5 h at room temperature.The solvent with the CEO was dried in a forced convection dryingoven (Riossa, model E-51, Mexico City, Mexico) at 6080 C untilconstant weight was achieved. The weight of CEO collected afterextraction was taken as the content of total CEO in M.

2.2.8. CEO encapsulation efciencyThe encapsulation efciency (EE) of CEO in M was obtained

from surface and total CEO contents according with the followingequation (Jafari et al., 2007a):

EE Total CEO Surface CEOTotal CEO

100 4

where total CEO is the internal and surface oil content of M, whilesurface CEO corresponded to the unencapsulated oil content foundat the surface of the particles as mentioned above.

2.3. Statistical analyses

Analyses were performed in triplicate for each sample for all thetests, and data is presented as means standard deviation (SD).Data were analysed using a one way analysis of variance (ANOVA)and a Tukey test for a statistical signicance P 6 0.05, using theSPSS Statistics 19.0 (IBM Corporation, NY, USA).

E) variations.

uted emulsions code Co:Wa ratio TSC (%)

-MG,30 1:2 30-MG,30 1:3 30-MG,40 1:2 40-MG,40 1:3 40-GA,30 1:2 30-GA,30 1:3 30-GA,40 1:2 40-GA,40 1:3 40

:Wa = core to wall material ratio; biopolymer binary blend ratio used in dry basistal solids content, respectively.

d Engineering 111 (2012) 1021093. Results and discussion

3.1. Droplet size, viscosity and rate of coalescence of the freshemulsions

Table 2 shows the initial d4,3 and the rate of coalescence after5 months of storage of E. The emulsions made with Co:Wa of 1:3displayed signicantly lower d4,3 than those made with Co:Wa of1:2, independently of the biopolymers binary blend used. Thebiopolymers blend inuenced the process of disrupting the inter-face to form droplets through its effect on the interfacial tension,which decreased rapidly as the concentration of the biopolymersblend was increased from zero, but soon tended to attain a limitingvalue, and further increase in its concentration had little effectupon the interfacial tension. As the relative amount of biopolymersblend to CEO increased, but TSC remained constant, the

biopolymers tended to diffuse to and adsorb at the interface morequickly, reducing incipient coalescence of the CEO droplets, so thatsmaller droplets were produced. Here it may be pointed out thatboth, GA and MG, despite their very large molecular weight, arecharacterized for having a branched spherical structure, so that

Table 2Initial volume-weighted mean diameter (d4,3) and rate of coalescence of the freshemulsions variations.

Fresh emulsions variations code d4,3 (lm) kC (s1) 108 R2

E1:2,WPC-MG,30 3.12 0.06b 1.54a 0.968E1:3,WPC-MG,30 2.54 0.01a 2.40b 0.970E1:2,WPC-MG,40 3.35 0.04c 2.27b 0.966E1:3,WPC-MG,40 2.56 0.02a 3.32c 0.949E1:2,WPC-GA,30 3.00 0.03c 2.25a 0.942E1:3,WPC-GA,30 2.33 0.04a 6.10c 0.959E1:2,WPC-GA,40 3.09 0.01d 3.69b 0.950E1:3,WPC-GA,40 2.66 0.01b 7.66d 0.922

Values with different letters represent signicant difference in the same wallmaterial (P 6 0.05).

D.A. Rodea-Gonzlez et al. / Journal of Foothey diffuse to the oilwater interface relatively rapidly, and dueto their compact conguration, they densely pack (together withWPC) the interface (Vernon-Carter et al., 2000). In Table 2 it canalso be observed that the fresh emulsions made with 40% TSCtended to have larger d4,3 than those made with 30% TSC. These re-sults indicate that the viscosities of the dispersed (gD; 0.018 Pa s,Fig. 1) and continuous (gC) phases also played a role in determiningdroplet size (Charcosset, 2009). Presumably, at higher TSC, the vis-cosity of the continuous phase, and thus of E variations, increasedrespect that of CEO (Fig. 1), so that the specic area per unit vol-ume of emulsion decreases with decrease of gD/gC (Gopal, 1969).The viscosity-shear rate curves in Fig. 1 indicate that E variationsexhibited typical structural viscosity behaviour, characterized bya Newtonian behaviour at very low and very high shear rates, withshear thinning or pseudo-plastic behaviour at intermediate shearrates. In systems such as polymeric uids and occulated emul-sions this can be attributed to a reversible structure or networkthat forms in the rest or equilibrium state. When the system issheared, the structure breaks down, resulting in a shear dependent(shear thinning) behaviour (Darby, 2001). All E variations ttedwell (R2P 0.922, Table 2) a rst order rate of slow coalescencemodel (Sherman, 1969), exhibiting kC of magnitude 108 s1 inall cases, indicative of a high stability (Kitchener and Musselwhite,

1000E1:2, WPC-MG, 30

E1:3, WPC-MG, 300.01 0.1 1 10 1000.01

0,1

1

10

100 E1:2, WPC-MG, 40 E1:3, WPC-MG, 40 E1:2, WPC-GA, 30 E1:3, WPC-GA, 30 E1:2, WPC-GA, 40 E1:3, WPC-GA, 40 CEO

Visc

osity

(Pa s

)

Shear rate (s-1)

Fig. 1. Apparent viscosity-shear rate plots for the fresh emulsions (E) variations andfor chia essential oil.1969; Ruz-Ramos et al., 2006). This high stability displayed maybe attributed to the good surface-active properties (Jimnez-Alva-rado et al., 2009; Romn-Guerrero et al., 2009) of GA, MG and WPCwhich possess hydrophobic groups that are numerous enough andsufciently accessible in a short timescale to enable them toadhere to and spread out at the interface, thereby protecting thenewly formed droplets from aggregating or coalescing throughsteric stabilisation and electrostatic stabilisation mechanisms(Dickinson, 2003). Furthermore, in the case of associative adsorp-tion, when an adsorbed layer containing a mixture of two differentsurface-active components (WPC-GA or WPC-MG) is formed, if thissituation is to be stable (as evidenced by kC), the adsorption of thesecond component should either be enhanced by the presence ofthe rst component, or not inuenced by it. Polyelectrolytes suchas GA and MG can associate with proteins (i.e. WPC) through elec-trostatic attaction, hydrogen bonds, or Van der Waals forces to en-hance the steric stabilizing properties of the droplets (Mishra et al.,2001). Physico-chemical properties of protein-polysaccharidecomplexes increase the entropy of mixing of biopolymers and theirco-solubility contributing to more stable emulsions (Tolstoguzov,2003). Despite that all the fresh emulsions showed high stabilityagainst droplet coalescence, the E variations with 30% TSC showedsignicantly lower kC than their 40% TSC counterparts for a givenCo:Wa, and the emulsions made with the biopolymers blend con-taining MGwere signicantly more stable against coalescence thanthose containing GA. These results pinpoint that probably a morebalanced composition between the adsorbed biopolymers at theinterface (i.e. when Co:Wa is 1:2) allows for a greater associationbetween them and a more structured interfacial membrane forma-tion than when Co:Wa is 1:3. On the other hand, it has been re-ported that MG has a considerably greater molecular weight(2,120,000 Da) (Vernon-Carter et al., 1998) than GA (1,000,000Da) (Fenyo and Vandevelde, 1990), so that it is probable that theadsorbed layer around the emulsions containing MG are thickerthan those containing GA, so that the steric repulsion stabilizationterm is likely to be larger (Jimnez-Alvarado et al., 2009).

3.2. Properties of microcapsules and encapsulation efciency

The microcapsules variations prepared with WPC-MG biopoly-mers blend showed signicant lower moisture content as TSCincreased from 30% to 40%, but non-signicant differences whenCo:Wa varied from 1:2 to 1:3 for a given TSC (Table 3). In contrast,the microcapsules prepared with the WPC-GA biopolymers blendwere signicantly different from each other, whatever theircomposition. The M variations with 40% TSC exhibited signicantlylower moisture than those with 30% TSC, and moisture content wassignicantly lower when Co:Wa was 1:3 than when it was 1:2. Thiscontrasting behaviour can be probably attributed to differentsorption mechanisms taking place in the biopolymers blends. Ina previous work, Prez-Alonso et al. (2006) reported that GA andMG monolayers exhibited different trends in their sorptionisotherm behaviour with temperature, and blends of either of thesetwo hydrocolloids with maltodextrin DE 10 followed similarsorption isotherms behaviour trends as GA and MG on their own.The isotherm behaviour of WPC has been reported to follow asimilar trend as that of MG (Hermansson, 1977).

The microcapsules d4,3 was approximately 4.5- to 10-fold-timeslarger than that of the E variations from which they were obtained(Table 3), and the microcapsules obtained from the emulsions with40% TSC had a signicantly higher d4,3 than those obtained fromthe emulsions with 30% TSC. The microcapsules particle size isinuenced by the nozzle, liquid delivery rate, atomizing conditions,

d Engineering 111 (2012) 102109 105air pressure and TSC (McNamee et al., 1998). In this study, all theemulsions were spray dried under identical operational conditionsso that the variations in particle size of microcapsules are most

t ch

mi

(P 6

f FooTable 3Particle size, moisture content, surface oil, and encapsulation efciency of the differen

Microcapsules variationscode

Microcapsule size (d4,3,lm)

Moisture content of(wt%)

M1:2,WPC-MG,30 14.91 0.67a 5.26 0.08b

M1:3,WPC-MG,30 16.30 0.73a 5.16 0.07b

M1:2,WPC-MG,40 23.06 1.04b 4.90 0.07a

M1:3,WPC-MG,40 27.60 1.10c 4.75 0.07a

M1:2,WPC-GA,30 13.17 0.60a 5.38 0.08d

M1:3,WPC-GA,30 18.63 0.84b 5.19 0.08c

M1:2,WPC-GA,40 24.28 1.09c 4.85 0.08b

M1:3,WPC-GA,40 28.20 1.27d 4.34 0.08a

Values in the same wall material bearing different letters are signicant difference

106 D.A. Rodea-Gonzlez et al. / Journal olikely due the changes in TSC. Rodrguez-Huezo et al. (2004) W/O/W multiple emulsions stabilized with GA-MG-MD10 biopolymersblends produced microcapsules with signicantly larger d4,3 whenTSC of the multiple emulsions was higher. These authors demon-strated that emulsions with higher TSC had higher apparent viscos-ities than emulsions with lower TSC, and that at temperaturesreaching or exceeding the boiling point of water (as occurred dur-ing spray-drying) large partial pressures of water vapour developas the droplet temperature increases, joining entrapped air bub-bles. A driving force of dissolved gases from the feed during dryingwill occur as water is evaporated and as the droplet temperatureincreases, lowering the solubility of air. Higher apparent viscositieslimit the diffusion of gases through the viscous network, and a bal-loon like expansion of the droplets occurs, and the expansion ofdroplets continues until a threshold of partial pressure of the gasesis reached and exceeded (Rodrguez-Huezo et al., 2004). The vio-lent diffusion of gases through the viscous matrix may result inthe formation of cracks and ssures in the dry skin (R, 1998).

The surface oil was signicantly higher and the EE was signi-cantly lower in the microcapsules variations made with higherTSC than those made with lower TSC, independently of the

Fig. 2. Micrographs of the surface topology of microcapsules with WPC-MGbiopolymers blend as wall material and 30% total solids contents: (a) Co:Wa of1:2, and (b) Co:Wa of 1:3.ia essential oil microcapsules variations.

crocapsule Surface oil (g/100 gmicrocapsule)

Encapsulation efciency(%)

10.60 0.53c 74.10 1.85a

4.08 0.20a 80.70 2.02b

13.20 0.66d 71.40 1.79a

6.40 0.32b 78.40 1.96b

11.26 0.56b 72.60 1.82a

5.70 0.29a 79.80 2.00b

13.80 0.69c 70.70 1.77a

6.70 0.34a 77.70 1.94b

0.05).

d Engineering 111 (2012) 102109biopolymers blend composition (Table 3). Surface oil and EE werenot affected by particle size of the microcapsules variations(Table 3). Our results are in agreement with those reported bySoottitantawat et al. (2005), but are in contrast with those reachedby Jafari et al. (2007b) who reported that EE can be improved byhaving narrowly distributed powder particles with optimum size,which was

3.3. Microcapsules SEM micrographs

SEMmicrographs are shown in Figs. 2 and 3 for the M variationsmade with Co:Wa of 1:2 and 1:3 ratios and 30% TSC with WPC-MGand WPC-GA, respectively. All the M variations exhibited an outer

topography characterized by more or less dimpled sphericalshapes, free of cracks and craters, independently of the binary bio-polymer blends used. These results corroborate that structurallyrobust microcapsules are obtained from emulsions that presentgood stability against droplet coalescence (Liu et al., 2001;Danviriyakul et al., 2002; Barbosa et al., 2005; Quintanilla-Carvajalet al., 2011). Observation of the SEM micrographs of the microcap-sules with Co:Wa of 1:2 and 1:3 ratios for WPC-MG (Fig. 2a and b)and for WPC-GA (Fig. 3a and b), respectively, indicate that as thecore to wall material ratio decreased, more uniform sizedmicrocapsules were formed.

3.4. Droplet distribution of fresh and reconstituted emulsions

A relevant functional property of microcapsules in practicalapplications is their ability to form stable emulsions when redi-spersed in water. The RE exhibited larger d4,3 than the E variations,but in all cases maintained kC of magnitude 108 s1 (Table 4), andthus, high stability against change in droplet size (coalescence).Figs. 4 and 5 show the initial droplet size distribution proles ofthe E variations with 30% TSC and stabilized with the biopolymers

Table 4Initial volume-weighted mean diameter (d4,3) and rate of coalescence of thereconstituted emulsions variations.

Reconstituted emulsionsvariations code

d4,3 (lm) kC (s1) 108 R2

RE1:2,WPC-MG,30 8.31 0.37c 9.90a 0.958RE1:3,WPC-MG,30 5.54 0.50b 9.94b 0.995RE1:2,WPC-MG,40 5.01 0.37b 1.46b 0.963RE1:3,WPC-MG,40 3.25 0.18a 8.10c 0.965RE1:2,WPC-GA,30 9.01 0.22c 1.27a 0.942RE1:3,WPC-GA,30 4.20 0.16b 8.86c 0.981RE1:2,WPC-GA,40 3.77 0.32b 1.84b 0.944RE1:3,WPC-GA,40 2.97 0.06a 9.26d 0.955

Values with different letters represent signicant difference in the same wallmaterial (P 6 0.05).

0.01 0.1 1 10 1000

2

4

6

8

10

Fresh emulsion Reconstituted emulsion

Vol

ume (

%)

Emulsion droplet size (m)

2

4

6

8

10

12

Fresh emulsion Reconstituted emulsion

Vol

ume (

%)

(a)

(b)

0.01 0.1 1 10 1000

2

4

6

8

10

12

Fresh emulsion Reconstituted emulsionV

olum

e (%

)e

(a)

D.A. Rodea-Gonzlez et al. / Journal of Food Engineering 111 (2012) 102109 1070.01 0.1 1 10 1000

Emulsion droplet size (m)Fig. 4. Fresh and reconstituted droplet size distribution for emulsions variationsstabilized withWPC-MG biopolymers blend and 30% total solids contents: (a) Co:Waof 1:2, and (b) Co:Wa of 1:3.0.01 0.1 1 10 1000

2

4

6

Vol

um

Emulsion droplet size (m)Emulsion droplet size (m)

8

10

12

Fresh emulsion Reconstituted emulsion

(%)

(b)Fig. 5. Fresh and reconstituted droplet size distribution for emulsions variationsstabilized with WPC-GA biopolymers blend and 30% total solids contents: (a) Co:Waof 1:2, and (b) Co:Wa of 1:3.

Barbosa, M.I.M.J., Borsarelli, C.D., Mercadante, A.Z., 2005. Light stability of spray-

f Foodried bixin encapsulated with different edible polysaccharide preparations.Food Research International 38 (89), 989994.

Benichou, A., Aserin, A., Garti, N., 2002. Protein-polysaccharide interactions forstabilization of food emulsions. Journal of Dispersion Science and Technology23, 93123.

Beristain, C.I., Vernon-Carter, E.J., 1994. Utilization of mesquite (Prosopis juliora)gum as emulsion stabilizing agent for spray-dried encapsulated orange peel oil.Drying Technology 12, 727733.

Beristain, C.I., Vernon-Carter, E.J., 1995. Studies on the interaction of mesquite(Prosopis juliora) gum as emulsion stabilizing agents for spray-driedencapsulated orange peel oil. Drying Technology 13 (12), 455461.

Charcosset, C., 2009. Preparation of emulsions and particles by membraneemulsication for the food processing industry. Journal of Food Engineering92 (3), 241249.

Danviriyakul, S., McClements, D.J., Decker, E., Nawar, W.W., Chinachoti, P., 2002.Physical stability of spray-dried milk fat emulsion as affected by emulsiers andprocessing conditions. Journal of Food Science 67 (6), 21832189.

Darby, R., 2001. Chemical Engineering Fluid Mechanics, 2nd ed. Marcel Dekker, Inc.,New York, pp. 6771.

Darling, D.F., 1987. Kinetic aspects of food emulsion behavior. In: Blanshard, J.M.V.,Lillford, P. (Eds.), Food Structure and Behavior. Academic Press, London,blends WPC-MG and WPC-GA, respectively. In general terms itmay be observed that the droplet size distribution prole of theE variations was unimodal and that the distribution tended to shifttowards smaller droplet sizes as Co:Wa was increased from 1:2(Figs. 4a and 5a) to 1:3 (Figs. 4b and 5b), independently of the bio-polymers blend used. The RE variations tended to show a multi-modal size distribution prole that was considerably wider thanthat for the E variations. The droplet size prole tended to showsmaller shoulders at Co:Wa of 1:3 than at 1:2. Similar trends, butwith narrower size distribution proles were obtained for the Eand RE variations with 40% TSC (data not shown). Jafari et al.(2007a,b) have stated that droplet size distribution and stabilityof emulsions is crucial for obtaining stable microcapsules with highEE, as the embedded core material droplets in the microcapsulesshell achieve maximum protection.

4. Conclusions

Chia essential oil-in-water emulsionsmadewith 40% total solidscontent and a core to wall material of 1:3 produced microcapsuleswith higher encapsulation efciency. Encapsulation efciency wasindependent of microcapsules particle size. Microcapsules smallerparticle was smaller when core to wall material was higher. Bothbinary biopolymers blends formed fresh and reconstituted emul-sions stable against droplet coalescence. Coalescence rates for thereconstituted emulsions were of the same order as that of the freshones. This study provides insights for obtaining stable chia essentialoil-in-water emulsions, which upon spray-drying deliver morpho-logically sound microcapsules with good encapsulation efciency.

Acknowledgments

The authors wish to thank the partial nancing of this researchto the Universidad Autnoma del Estado de Mxico through Grant3118/2011 and to the Consejo Nacional de Ciencia y Tecnologa(CONACyT) through Grant U-81157-Z.

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D.A. Rodea-Gonzlez et al. / Journal of Food Engineering 111 (2012) 102109 109

Spray-dried encapsulation of chia essential oil (Salvia hispanica L.) in whey protein concentrate-polysaccharide matrices1 Introduction2 Materials and methods2.1 Materials2.2 Methods2.2.1 Preparation of the oil-in-water emulsions2.2.2 Viscosity of emulsions2.2.3 Preparation of microcapsules by spray-drying2.2.4 Morphology of microcapsules by scanning electronic microscopy (SEM) analysis2.2.5 Fresh and reconstituted emulsions droplet and microcapsule particle sizes2.2.6 Moisture content of the microcapsules2.2.7 Surface and total CEO content in microcapsules2.2.8 CEO encapsulation efficiency

2.3 Statistical analyses

3 Results and discussion3.1 Droplet size, viscosity and rate of coalescence of the fresh emulsions3.2 Properties of microcapsules and encapsulation efficiency3.3 Microcapsules SEM micrographs3.4 Droplet distribution of fresh and reconstituted emulsions

4 ConclusionsAcknowledgmentsReferences