Antioxidant and functional properties of tea protein as affected by the different tea processing methods.

The Box-Behnken design combined with response surface methodology was used to optimize alkali extraction of protein from tea. Three independent extraction variables (extraction time: X1; extraction temperature: X2; alkali concentration: X3) were evaluated. The antioxidant and functional properties of tea protein as affected by different tea processing were compared. The optimum conditions were: extraction time of 85 min, extraction temperature of 80 °C, and alkali concentration of 0.15 M. Under such conditions, the predicted maximum protein extracted yield was 20.73 %, which coincided with the experimental values. Three kinds of tea protein showed good antioxidant and functional properties. Tea processing method had a significant impact on the properties of tea protein. Protein from oolong tea showed the best properties and it might be used as a good source of potential antioxidant and additives in food industry.