Preparation And Characterization Of Tannic Microcapsules With Multiple Emulsified Structures

Tannic acid has many biological activities such as antioxidation,anticancer,bacteriostasis and disinfection.However,due to its unstable structure,easy oxidation,dark color after oxidation,easy moisture absorption and special smell,tannic acid has greatly limited its application and development in cosmetics.Through the two-step emulsification method,the tannic acid microcapsules with multiple emulsification structures were successfully prepared in this paper.The effects of six factors,such as core-wall ratio,shear pressure,wall material content,Tween 20 content,water-emulsion ratio of multiple emulsions and secondary emulsification temperature,on the embedding rate,embedding efficiency and particle size of tannic acid microcapsules were studied,so as to obtain more high-quality products.Finally,the optimum preparation conditions were obtained by orthogonal design test:the ratio of core to wall was 1:1,the content of wall material was 3%,the content of Tween 20 was 2%,and the secondary emulsification temperature was 50 ℃.The appearance,particle size,encapsulation efficiency and encapsulation effect of microcapsules can be studied by means of metallographic microscope,scanning electron microscope(SEM),Marvin particle size analyzer and ultraviolet spectrophotometer.The average particle size of tannic acid microcapsules prepared under the optimum conditions reached 21.0 μ m.The embedding rate reached 46.44%,and the embedding efficiency also reached 92.88%.Through Fourier transform infrared spectroscopy and TG analysis,it was found that tannic acid had been successfully encapsulated in microcapsules and had good thermal stability.In addition,by comparing the leakage rate and p H change of tannic acid and tannic acid microcapsules for 7consecutive days,it was proved that the microcapsule structure was stable,the core material was not easy to leak,and the acidity of microencapsulated tannic acid was significantly reduced.After the chick embryo chorioallantoic membrane test,it was found that tannic acid microcapsules would not cause any harm to human skin or eyes,which is consistent with the concept of green environmental protection.