Abstract: Objective: To optimize the extraction process for Pu-erh tea pigment and explore its antioxidant activity. Methods: Following single factor investigations, optimization of process conditions for the extraction of Pu-erh tea pigment based on the color difference value E between distilled water and Pu-erh tea pigment was carried out using central design composite design combined with response surface methodology (RSM). 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay was used to evaluate the antioxidant activity of the pigment. Results: The optimal extraction conditions for Pu-erh tea pigment were liquid-to-material ratio of 45:1 (mL/g), extraction temperature of 100 ℃ and extraction time of 150 min. Under the optimal extraction conditions, a color difference E value of 52.97 was obtained, which revealed 4.73% increase as compared to the highest color difference in single-factor investigations and Box-Behnken composite experiments. The IC50 value for the scavenging capability of Pu-erh tea pigment on DPPH free radicals was 30.83μg/mL. Conclusion: It is feasible to optimize the extraction of Pu-erh tea pigment by response surface methodology. The Pu-erh tea pigment with excellent antioxidant activity has the potential to be further developed and utilized as a natural antioxidant.

Key words: Pu-erh tea, tea pigment, extraction, response surface methodology, antioxidant activity