Abstract: In this study,multiple quadratic regression equation model for the optimization of acetylation conditions of tea polyphenol was established by response surface analysis.The condition of acetylating tea polyphenol was optimized using DPPH free radical scavenging rates as index.The optimized acetylating conditions were as follows:liquid-to-solid ratio was 8.31,catalyst dosage was 0.32 g and reflux reaction under 61.5 ℃ for 2.03 h.The DPPH free radical scavenging rates of the synthesized compound achieved 0.9318,with RSD of 0.64% compare with the predicted value.It was 7.64 times to that of the unmodified tea polyphenol.In addition,the light transmittance of the synthesized compound was 0.926.The lip-solubility of the synthesized compound was 4.2 times more than that of unmodified tea polyphenol.The antioxidant activity of modified tea polyphenol was better than BHA and TBHQ.

Key words: tea polyphenol, acetylation, DPPH free radical scavenging rates, response surface analysis