Abstract: The effects of temperature, heating time, ratio of tea to water and pH value on extraction rate and activities of Oolong tea, Green tea and Black tea polysaccharides(TPS) were studied. The results showed that extraction rate of TPS was noticeably affected by pH, temperature, heating time and ratio of tea to water in significant order. It was concluded that pH was the main factor affecting activity of TPS, since activity of TPS extracted on the condition of acidity or alkalinity was very low. The model of extraction rate (Y) showed no significant lack of suitability at 5%, but it was statistically significant at 1%. The model was appropriate to express response variables. Considering high extraction rate and activity of TPS, the extracting condition was optimized by using expectant function approach for simultaneous optimization of several variable levels, these were 0~1 temperature, 0~1 heating time, 0~0.5 ratio of tea to water and -0.95 pH.

Key words: tea polysaccharides, extraction, activity