Abstract:Using octenyl succinic acid-modified starch and soybean protein isolate as composite wall materials, microencapsulated persimmon tannin was prepared by spray drying. In terms of the embedding rate and cost, the optimum proportion of wall material and core material was 20:1 (m/m). The embedding rate of microcapsules was 94.3%, and the embedding yield was 92.4%. By orthogonal experiment, the optimum conditions for the preparation of microcapsules were as follows: inlet air temperature 388 k, feeding rate 3.0×10-3 L/s, and blower flow rate 0.050 m3/s. Under these conditions, the powder collection rate was 92.03%. Microcapsule particle size analysis, scanning electron microscopy, and infrared spectrum analysis revealed that an embedding effect existed in the composite wall materials and persimmon tannins, and the microcapsules exhibited the characteristics of the wall material. Physiochemical property analysis demonstrated that the water solubility of tannin was increased by 10 times after microencapsulation; with the protection from the wall material, the microencapsulated persimmon tannin retained a strong antioxidant activity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging ability, and its stability in aqueous solution was improved significantly. The microencapsulated persimmon tannin could be released in gastric juice and the intestinal tract, and the intestinal release effect was better than that in gastric juice, with a release rate of 80% within 40 min.
