Biện pháp tiền xử lý và tối ưu hóa quá trình trích ly anthocyanin từ vỏ khoai lang tím

Abstract

In this study, the pretreatment of purple sweet potato peel was conducted (steaming at 100oC for 4 min or not steaming combined drying at 50oC for 4 hours and control sample) to increase extraction efficiency of anthocyanin compounds. Optimization of purple sweet potato peel (Ipomoea batatas (L.) Lam) anthocyanins extraction was investigated using Response Surface Methodology (RSM), with ethanol concentrations (60, 70, 80%) at different extraction temperatures (40, 50, 60°C) and time (30, 45, 60 min). The combined effects of extraction conditions on anthocyanin content were studied using a three-level three-factor Box–Behnken design. The results showed that steaming of purple sweet potato peel at temperature of 100°C for 4 min, then drying at 50°C for 4 hours could increase extraction efficiency (anthocyanin content was 0.2%, increased 7 times compared to the control sample 0.03%). RSM was used to optimize the extraction parameters. The second order polynomial equation obtained (R2 = 0.94) indicated that extraction time mostly affected the extraction yield (as anthocyanin content). The optimal conditions (temperature, time and ethanol concentration) for extraction of anthocyanin were 51oC, 44 min and 68%, respectively. The experimental value of anthocyanin content was 0.274%. The experimental responses were reasonably closed to the predicted responses (R2= 0.93) and the optimum conditions of the extraction process were verified.