Study On The Microcapsulation Of Vitamin E By Complex Coacervation

Vitamin E is one of the most important and essential natural nutrition, which can protect biological membranes against lipid peroxidation as radical scavenger. Vitamin E are added to many foodstuffs as functional additives.But VE is destroyed easily when it is exposed under the oxygen and ultraviolet radiation, Microencapsulation provides several advantages in the food industry by protecting the core materials from their environments. The microcapsules offer the food processors a means to protect sensitive food component. Complex coacervation is the spontaneous liquid/liquid phase separation that occurs when oppositely charged colloids are mixed as a result of electrostatic attractions. The coacervation process occurs under mild conditions, consequently has great potential for the microencapsulation of certain materials which are unable to withstand harsh conditions involved in other microencapsulation processes.The yield and efficiency of microencapsulation by complex coacervation are high, but cross-linking agents usually are formaldehyde or glutaraldehyde, so the application of products is limited bedly, it is very important to study nontoxic cross-linking agents. In this paper, Vitamin E was microencapsulated using complex coacervation of gelatin /gum arabic, transglutaminase was a cross-linking agent. The preparation processing, physical and chemical properties, release kinetic equation and storage stability were studied.Preparation processing of VE microcapsules by complex coacervation was investigated, Response surface methodology (RSM) was used to optimize microencapsulation efficiency (ME) including three independent variables: the wall material Concentration(X₁), the wall material/core material ratio(X₂), and the pH value(X₃). A polynomial regression model equation was fitted as follows: ME(%)=92.6433+2.7012X₁+0.6775X₂-0.1562X₃-2.8617X₁²- 0.6175X₁X₂-1.3792X₂²+1.98X₁X₃-0.4125X₂X₃-11.5817X₃² .Applying this model equation to the surface plot and canonical analysis, The optimal conditions obtained for the VE Microencapsulation by Complex Coacervation: wall material Concentration 1.23%( X₁), wall material/core material ratio of 2.14:1(X₂), pH value of 4.0(X₃). The resulting ME, with the optimized condition, was ME (92.78%±0.65) which were coincident with predicted value(93.32%).Physical and chemical properties of vitamin E microcapsules were researched.The moisture was1.80% and fit to store, the density was 0.56g/mL, the repose angle was35.1°, and fluid was good. The microstructure was valued by scanning electron microscope and showed that the surface of microcapsules was compact and integral. FT-IR spectrum proved that the coacervate was formed by the physical interaction between gelatin and gum arabic, not chemical interaction. Glass transition temperature (Tg) of vitamins E microcapsules by differential scanning calorimetry (DSC) was at 35.3℃which indicated the storage stability was good because both of the encapsulation products were at the glass state in normal temperature storage(25℃). Thermogravimereic analysis(TGA) showed the wall materials protect the core materials to some extent. The stability of microcapsules by complex coacervation in 150℃was investigated, the losing rate of VE decreased dramatically after microencapsulation, the gradual release in hot water (80℃) was batter than the microcapsules by normal spray-drying obviously.The release kinetic equation in artificial simulation gastric juice was studied. In 0 to120min,the release equation was y = 1.6038e^0.0312x,R² = 0.9815; In 120 to 200min,the the release equation was y = 0.3237x + 17.356,R2 = 0.9888。The influence of light,temperature and relative humidity on stability of microcapsules was researched. The results showed as follows: Compared with the condition in light, the losing rate of VE in light-proof condition decreased ; Microcapsules were stable in 4℃and 25℃, after ninety days, the stability was decreased in 45℃; Microcapsules stored stably in low humidity (RH=33%, 58%), when relative humidity rised to 79%, the reservation rate was decreased dramatically. The light, temperature and relative humidity have a significant effect on the storage stability of products.