Optimization of Extraction Process of Tea Protein by Mixed Reverse Microemulsion System

Three reverse microemulsion systems were prepared using sodium bis (2-ethylhexyl) sulfosuccinate (AOT), cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and Tween80, and the effects of surfactant concentration, ionic surfactant content, water content (W₀), aqueous phase pH, extraction temperature and extraction time on protein forward extraction yield and KCl concentration, aqueous phase pH and extraction temperature on protein backward extraction yield were investigated by single-factor experiments, then the optimal extraction conditions were obtained by orthogonal experiments. The results showed that the Tween80-CTAB microemulsion system was effective for the extraction of tea residues protein, and under the optimal conditions of surfactant concentration of 0.10 mol/L, ionic surfactant content of 70%, aqueous phase pH13.0, W₀ 25, extraction temperature of 40 ℃ and extraction time of 40 min, the forward extraction yield of tea residues protein reached the maximum value of 16.17%. Under the optimal conditions of KCl concentration of 1.2 mol/L, pH7.0 and extraction temperature of 40 ℃, the backward extraction yield of residues protein could reach 94.78%. SDS-PAGE showed that the molecular bands of tea residues protein obtained by reverse microemulsion extraction were small, which could selectively extract small molecular proteins.