Optimization of Extraction Process of Protein from Exhausted Tea by Alkaline Electrolyzed-Reducing Water Synergized with Protease

Protein extracted from exhausted tea possessed great antioxidant activity. In this study,alkaline electrolyzed-reducing water synergized with protease was adopted to extract protein from exhausted tea. Based on the single factor experiments,orthogonal test was employed to optimize the extraction conditions of protein from exhausted tea,and an alkaline protease was further selected to improve the protein extraction rate. Orthogonal test results showed that the optimal extract conditions were as follows:pH12.5,extraction temperature 120 ℃,extraction time 40 min and 40∶1 of liquid-solid ratio(mL/g),and the extraction rate of protein yield reached to 48.3% under the optimal conditions. The extraction parameters of protein in the exhausted tea by protease were further optimized,the results showed that the yield of protein in exhausted tea was 83% under the extraction conditions:pH9,hydrolysis time 32 h,enzyme amount 2500 IU/g exhausted tea. Compared with the former,extraction rate of protein in exhausted tea increased significantly with the synergistic action of alkaline protease by 34.7%. Besides,the protein possessed high total antioxidant capacity. This study provided a theoretical basis for the comprehensive utilization of exhausted tea and the effective development of new protein resources.