Process of inspissated Rhodomyrtus tomemtosa (Ait.) Hassk juice rich in anthocyanins through vacuum evaporation

An concentrated Rhodomyrtus tomemtosa (Ait.) Hassk juice rich in anthocyanins was prepared by vacuum evaporation. Firstly, the protective effects of citric acid, ascorbic acid and zinc ion on anthocyanin were evaluated during juicing. Then, the anthocyanin concentrated effects of vacuum evaporation temperature and time were determined and optimized. The results showed that the content of anthocyanin increased significantly by adding citric acid in juicing, and the protective effects by ascorbic acid and zinc ion were only observed within low levels. The anthocyanin concentration could be improved by thermal enzymatic hydrolysis. Furthermore, vacuum evaporation was an efficient way to increase the content of anthocyanin which was mainly determined by the temperature and time. R. tomemtosa (Ait.) Hassk juice with high concentration anthocyanin could be processed in the conditions of pulping with 0.6 g/kg citric acid, 0.1 g/kg ascorbic acid and 1.0 mg/kg zinc sulfate, enzymolysis in 50℃ for 1 h, vacuum concentration in 65℃ for 90 min, and the concentration of anthocyanin in R. tomemtosa (Ait.) Hassk juice would be enhanced more than 30 times.