Theanine supplementation in tea wine production: Accelerated fermentation, refined aroma profile, and enhanced sensory quality.

Tea wine, a popular beverage in China, is hampered by sluggish fermentation due to assimilable nitrogen deficiency in tea infusion. This study systematically evaluated the effects of different nitrogen sources (theanine, glutamate, diammonium phosphate, and ammonium sulfate) on tea wine production. Results demonstrated that nitrogen supplementation significantly enhanced yeast growth and fermentation efficiency. Theanine proved most effective, shortening the fermentation duration by 37.5% and increasing the maximum ethanol concentration by 13% compared to the control. It also refined the volatile profile by promoting a balanced synthesis of fruity esters (ethyl hexanoate and isoamyl acetate) and limiting excessive ethyl acetate. Moreover, theanine-supplemented tea wine achieved the highest overall sensory acceptability score (7.69), which was 15.6% greater than the control, and exhibited significantly improved clarity. This study demonstrates that theanine is an ideal nitrogen source for producing high-quality tea wine efficiently.