Optimisation of clarification process of glutinous rice tea wine, and its antioxidant activity

Abstract

Glutinous rice tea wine is an alcoholic beverage with antioxidant function which has good market value. However, it is prone to turbidity and precipitation during storage. To improve the unstable quality of glutinous rice tea wine, pectinase is used to clarify it. Based on single factor test and response surface test, the optimal clarification process parameters of pectinase, including pectinase addition, enzymolysis temperature, and enzymolysis time were optimised. Then, the antioxidant activity of glutinous rice tea wine was determined. Results showed that the effect of three clarification treatments on the clarification of glutinous rice tea wine was in the order of pectinase addition > enzymolysis temperature > enzymolysis time, and the optimal clarification conditions were: pectinase addition was 0.4 mL/L, enzymolysis temperature was 40.3°C, and enzymolysis time was 120.2 min. Under the optimal condition, the transmittance of glutinous rice tea wine was 92.3%, while the half maximal inhibitory concentration (IC50) of glutinous rice tea wine on the scavenging rates of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·), hydroxyl radical (·OH), and superoxide anion radical (O2-·) were 53.64, 41.18, and 66.56 mg/mL (ethanol content), respectively. Therefore, glutinous rice tea wine had certain antioxidant capacity and health promotion effect which provided a theoretical basis for improving the added value of medium- and low-grade teas.