ENCAPSULATION OF TOCOPHEROL ANDTOCOTRIENOL IN VITAMIN-E USING SPRAY DRYING

TECHNIQUE

Siti Norina Selamat, Ida Idayu MUhamad, Mohamad Roji SarmidiDepartment of Bioprocess Engineering,

Faculty of Chemical Engineering and Natural Resources, UTM, Malaysia

ABSTRACT

The encapsulation technology by spraydrying technique was applied to protect vitaminE from unfavourable environment and tominimize the degree of vitamin E degradation.Vitamin E microencapsules were produced usinga blend of maltodextrin and sodium caseinate aswall materials. The surface morphology of themicrocapsules was observed by field emissionscanning electron microscopy, whichdemonstrated a tendency of agglomeration. Theouter surfaces of the capsules showed only a fewpores or cracks. The particles sizes measuredwere the range of 13 11m to 29 11m. Thetocopherol encapsulation efficiency andtocopherol retention after spray drying weremeasured by high-performance liquidchromatography. About 52-70% of tocopherolencapsulation efficiency has been achieved.

1. INTRODUCTION

Vitamin E is one of the most importantphytonutrients in edible oils. The term vitamin Eis used as a generic reference to tocopherol andtocotrienol compounds exhibiting the biologicalactivity of a-tocopherol (Ball, 1988). a­tocopherol is a well-known fat-solubleantioxidant and is widely used in the foodindustry (Chang, et a!., 2005). It is calledanti?~i~ant because of its ability ofquenching orstabllizmg free radicals that lead over time todegenerati ve diseases, including cancer andc~rdio:ascular disease (Yoo, et a!., 2006).Vltamlll E can be degraded rapidly in the

presence of oxygen, and free-radical mediatedoxidative processes. These obstructions ofvitamin E can be partially overcome by applyingmicroencapsulation technology to protect a­tocopherol from unfavorable environment and tosolubilize it in aqueous environment.

Microencapsulation is a process in whichsensitive ingredients or 'core' materials areentrapped in a protective polymer encapsulatingagent or 'walI' material (Hogan, et aI., 2001).Spray drying technique has been widely appliedin the food industry for encapsulating vitamins,minerals, and other sensitive ingredients (Yoo, eta1.,2006).

Carbohydrate such as maltodextrin has beenextensively used as encapsulating agents.Maltodextrins are non sweet nutritivepolysaccharides consisted of: a(1-4)-linked D­glucose produced by acid or enzymatichydrolysis of com starch. Althoughmaltodextrins do not promote good retention ofvolatile compounds during the spray dryingprocess, they protect encapsulated ingredientsfrom oxidation (Reineccius, 1991, Re, 1998).Maltodextrins, however, require an additionalemulsifYing agent for the encapsulating of lipids,as the formation of a stable emulsion of smaIlparticle size is normally required for thepreparation of a fat encapsulate (Risch &Reineccius, 1988). Sodium caseinate is usedbecause of its excellent emulsifYing and filmforming abilities (Surh, et al., 2006). Sodiumcaseinate contributes opacity, solubility, heatstability, and most importantly, the superb water­and fat-binding characteristics that make themsuitable as emulsifiers. It emulsifies so wellbecause of its structure - a random coil with ahydrophobic head and hydrophilic tail.

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The objective of the present study was toencapsulate mixed tocopherol and tocotrienolprotecting against loss by oxidation using ahydrophilic matrix in order to producemicrocapsules of antioxidant vitamin E forapplication in the food industry as fortification.The encapsulation was through spray dryingtechnique. Microcapsules of vitamin E producedwere water-soluble, which allowed moreindustrialized use of this vitamin in order toenrich foods such as, milk powder, flours,wholemeal, in short, into products with lowwater activity.

2. EXPERIMENT

2.1 Materials

Fully natural palm mixed tocopherol andtocotrienols concentrate was purchased fromSuper Vitamins Sdn. Bhd (Masai, Johor).Maltodextrin (DE 11-15) was purchased fromMerck (Damstadt, Germany). Sodium caseinate(protein content: 88%) was obtained from DMVInternational (Veghel-The Netherlands). Allother chemicals were of HPLC grade and werepurchased from Merck (Darmstadt, Germany).

2.2 Methods

2.2.1 Preparation of emulsions. Wallmaterial solutions containing blends ofmaltodextrin:sodium caseinate, both in the rangeof 18.5-24% w/w and 7-9% w/w, respectivelywere prepared in distilled water. The wallmaterial solutions were homogenized at 3000rpm for 20 minutes. A blend of palm naturaltocopherol and tocotrienol mixed concentratewas emulsified into the wall material solution.Core/wall ratio of 0.6, 0.7 and 1.0 were used. Inall cases, total solids content of feed solution was22-40% (w/w). The emulsification was carriedout at 3500 rpm for 30 minutes.

2.2.2 Spray drying. The emulsions werespray-dried using a pilot plant spray-drier (PilotSpray Drying Plant PSD-OO, Hernray Enterprise,Bombay, India) equipped with 0.5 mm diameternozzle. The inlet and outlet temperature wasmaintained at 110 °C and 90°C, respectively.The spray-dryer was operated at a feed rate of 10ml/min and air pressure of 55 kgfi'cm2

. Themicrocapsules were stored in a glass bottle at -20°C prior to analysis.

2.2.3 Tocopherol content determination.Vitamin E microcapsules (2.0 mg) weredispersed in 1.0 ml of hexane in order to breakthe microcapsules under vortex agitation. Themixture was filtrated using a 0.45 ~m

polytetrafluoroethylene (PTFE) membranebefore injection to the HPLC.

2.2.4 Encapsulation efficiency.Encapsulation efficiency was assessed bydetermining the total tocopherol content of thepowder and surface tocopherol. Theencapsulation efficiency was calculatedaccording to McNamee, et al. (2001), as shownbelow:

%EE = (TT - ST) x 100TT

Where:TT= total tocopherol and ST=surface tocopherol.

Total tocopherol and surface tocopheroldetermination were developed based on theconditions described by Barbosa, et al. (2005)for bixin extraction from encapsulated bixincrystals with some modifications. Microcapsules(1.0 g) were dispersed in distilled water (20 ml)then homogenized for I min under vortexagitation. The mixture was transferred to aseparation funnel then extracted with hexane(total of 40 rnI).Surface tocopherol was determined by directextraction of 1 g of microcapsules with 5 mlhexane by vortex agitation for 30 s, followed bycentrifugation (3000 rpm for 10 min). Afterphase separation, the liquid phase containing thetocopherol was collected and filtered through aPTFE membrane (0.45 flm) before analysed withHPLC. The analysis was carried out in duplicate.

2.2.5 HPLC analysis. The purity of tocopherol,either as liquid or spray-dried vitamin Emicrocapsules, was verified by HPLC. Theanalysis was carried out using a Waters HPLCsystem equipped with a photo-diode arraydetector (Waters, model 515). The equipmentalso included a Rheodyne 775i injection valvewith a 20 ~L loop and a column heater. Dataacquisition and processing were performed usingthe CSW Switch software.Separation of tocopherol from spray-driedmicrocapsules was achieved on a Synergy 4uhydro-RP 80A column (4 flm, 250 x 4.6 mm)detected at wavelength 292 nm withmethanol/acetonitrile (50:50 v/v) as a mobilephase at flow rate of 1.0 ml/min and column

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temperature set at 40°C. The condition waspreviously evaluated by Aoun, et al. (2005). Allsolvents were HPLC grade.

2.2.6 Scanning electron microscopy. Thesurface morphology of the microcapsules wasobserved by a scanning electron microscopy(SEM), Jeol, model JSM-6390 LV, Japan,following methodology described by Farias, etaI., (2007). The samples were placed on theSEM stubs (10 mm) using a two-sided adhesivetape. The specimens were subsequently coatedwith Platinum using an ion sputter coater. Thecoated samples were then analysed using theSEM operating at an accelerating voltage of ISkV.

3.3 Micrographs

The morphology of microcapsules can beobserved in Figure I to 3. One reason for usingSEM in studying microencapsulation is the needto visually determine the encapsulating ability ofthe wall materials. Indication of this ability couldbe further described by the retention andencapsulation efficiency of active materials inthe microcapsules.

Morphologic analysis showed the size, theshape and common aspects of the microcapsulesmade from the blend wall materials andcore/wall ratio of 0.6 (Fig. 1). Furthermore, thetendency of agglomeration of the smallestparticles between themselves and the biggestones was clearly observed.

3. RESULTS AND DISCUSSION.

3.1 Encapsulation efficiency (EE)

3.2 Retention of tocopherol content

Fig.1. Scanning electron micrograph of spray­dried palm mixed vitamin E emulsion stabilizedby wall materials combining sodium caseinateand maltodextrin prepared at a ratio of 1:3 andcore/wall ratio of 0.6.

Fig.2. Scanning electron micrograph of spray­dried palm mixed vitamin E emulsion stabilizedby wall materials combining sodium caseinateand maltodextrin prepared at a ratio of 1:3 andcore/wall ratio of0.7.

Table I Influence of core/wall ratio on theproperties of emulsion powders prepared at asodium caseinate/maltodextrin ratio of 1'3

In the present study, the encapsulationefficiency (EE) ranged from 52 to 70% (Table I).Increasing core/wall ratio from 0.6 to 1.0 hadlittle effect on EE of vitamin E microcapsules.This decrease in EE may have been due toinstability of the oil droplets in the emulsionbefore the spray drying process (Dian, et aI.,1996). It could also be due to the thinner layersof wall material between encapsulated oildroplets (Hogan, et aI., 200 I).

..Core/wall Powderratio Particle EE Retention

size (/lm) (%) (%)0.6 13 70 510.7 29 66 601.0 23 52 63

As shown in Table 1, about 51 to 63% of theinitial tocopherol remained in the powder afterspray-drying. The rest might have beendestroyed during spray-drying which was carriedout at a high temperature (110°C). Retention oftocopherol content in the microcapsules wereincreasing with the increased of core/wall ratio.This may suggest that, the higher oil content inthe emulsion, the higher percentage oftocopherol to be remained in the microcapsules.

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The difference in higher core/waH ratio i.e.0.7 could be observed in figure 2. The outersurfaces of the spray-dried microcapsules arecharacterized by the presence of dents and thesedents are most likely formed by shrinkage of theparticles during drying and cooling. Similardents were observed in the study of ascorbic acidencapsulation (Finotel1i and Rocha-Leao., 2005)using maltodextrin and Capsul (National starch)as wall materials. Although the outer surfaces ofthe capsules had some dents, they showed only afew pores or cracks.

SEMs of powders prepared at a core/wallratio of 0.6 appeared as discrete particles withboth smooth and wrinkled surfaces (Fig. I).However at a core/wall ratio of 0.7 and 1.0 (Fig.2 and 3) powder particles appeared highlyagglomerated may be due to high levels ofsurface oil (Hogan, et aI., 200l).

Fig.3. Scanning electron micrograph of spray­dried palm mixed vitamin E emulsion stabilizedby wall materials combining sodium caseinateand maltodextrin prepared at a ratio of 1:3 andcore/wall ratio of 1.0.

Dian, et al. (1996) reported that the higherthe oil content of emulsions the more surface oilwas found, with less oil being encapsulated. Itcould also be due to the effect of beinginsufficient wall material to encapsulate the oil,as the amount of oil was increased. However,according to Sankarikutty, et al. (1988) fromtheir work some of the oil on the surface may bedue to extraction of the oil from inside themicrocapsules that release out through cracks.Development of cracks could be affected by thetype of wall material used and also by the dryingconditions employed, especially the rate ofdrying (Dian, et aI., 1996).

Powder particle sizes are ranging from 13 to29 11m and it was not affected by core/wall ratio.However, according to Hogan, et al. (2001)

particle size of powder will be increased as afunction of both total solids concentration(emulsion) and spray-drier nozzle atomizer.

CONCLUSION

Mixcd tocopherol and tocotrienol weresuccessfully encapsulated using spray-dryingtechnique with blends of sodium caseinate andmaltodextrin as a wall material with thepercentage of encapsulation efficiency andretention of tocopherol were more than 50%. Thevitanlin E nlicrocapsules can be readily used asfood ingredient for application in food industry.

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Sankarikutty, B., Sreekumar, M.M.,Narayanan, C. S., and Mathew, A. G., Studies onmicroencapsulation of cardamom oil by spraydrying technique, Joumal ofFood Science andTechnology., voI25,no. 6,pp.352-356, 1988.

Surh, 1., Decker, 1. A., and McClements, D.1., Influence of pH and pectin type on propertiesand stability of sodium-caseinate stabilized oil­in-water emulsions. Food Hydrocolloids.,voI20,no. 5,pp. 607-618,2006.

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Ida Idayu Muhamad receivedthe BTech in IndustrialTechnology and M.Sc. in FoodScience, Universiti SainsMalaysia, and Ph.D in Chemicalengineering, U.K. (2005).

She is a Senior Lecturer,Department of BioprocessEngineering, UniversitiTeknologi Malaysia. Her currentinterests include modeling ofparticulate food systems,biopolymer process engineering,active and intelligent packaging,also implementation and auditingon industrial food safety systems(GRP, cGMP & RACCP).

Mohamad Roji Sarmidireceived the B.Sc. ChemicalEngineering, U.K. (1984), M.Sc.(Eng.) Biochemical Engineering,UK (1986), and Ph.D ChemicalEngineering, U. K. (1993).

He is a Professor, Departmentof Bioprocess Engineering,Universiti Teknologi Malaysia.His current interests includebioprocessing, metabolomic,metabolic profiling, and cellbased assay.

Siti Norina Selamat receivedthe B.Sc. (Rons.) in Biochemistry(2006) from Universiti PutraMalaysia.

She is a Postgraduate in M.(Eng.) Bioprocess Engineering,Universiti Teknologi Malaysia.Her current research is on theencapsulation of vitamin E frompalm oil.

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