Optimization of Microencapsulation Preparation Process and Controlled- release Properties of Elaeagnus angustifolia Flowers Essential Oil

In this study,β-cyclodextrin(β-CD)with porous structures was prepared and used as a food grade polymer for the microencapsulation of essential oil from Elaeagnus angustifolia flowers. The oil was impregnated in microspheres,and loading ratio was optimized by investigating the restrictive factors,including the ratios of oil to β-CD,ethanol to oil and β-CD to water,as well as the embedding temperature and time.Based on the screening of single-factor experiment design,four experimental factors were optimized for the Box-Behnken experimental design combined with response surface methodology. The results showed that the optimal extraction conditions were:the ratios of oil to β-CD,ethanol to oil and β-CD to water were 5∶1 (g/mL),30∶1 (mL/mL)and 8∶1 (mL/g)on the embedding temperature of 46 ℃ for 2 h.Under these conditions,the experimental loading ratio was 75.15%±0.24%,which was close to the predicted value. The presence of oil in the β-cyclodextrin was confirmed by Fourier transform infrared(FT-IR)spectroscopy and scanning electron microscopy(SEM). During the antioxidant experiments,the porous β-CD based microencapsulation exhibit a stable oil loading ratio(7.22%)and a significant improvement in oxidative stability(19.7%)compared with free oil. The newly-proposed process used in this work was easy to scale up for developing a new and attractive method for oil protection in the food industry.