Enzymatic reactions throughout cultivation, processing, storage and post-processing: Progressive sculpture of tea quality

Enzymatic reactions during tea growth, processing, storage and post-processing conduce to the diversity in the organoleptic qualities and health benefits of tea. While chemical component transformations by enzymatic catalysis have been extensively explored, the dynamic alteration of endogenous and exogenous enzyme activities throughout manufacture chains remain in a mist. This paper discusses main enzymatic reactions involved in tea growth, processing, storage and post-processing, including the dominant enzymes of specific processes, the chemical transformation driven by enzymes and the alteration of endogenous and exogenous enzymes activities. The direct and indirect regulatory factors influencing enzyme activities and their possible applications in tea production practice are also explored. The endogenous enzyme system of tea plants regulates secondary metabolism and stress defense, contributing to the primary accumulation of volatile and non-volatile compounds in tea plants. Endogenous enzymes activities altered unceasingly and are exposed to more substrates due to cell rupture during the withering, spread, rolling and tumbling stages, establishing the intricate substance basis for distinct organoleptic characteristics. Microbial or intentionally added exogenous enzymes, such as β-glucosidase and tannase, dominate during fermentation, storage, and post-processing, transforming chemical profiles to a more radical extent. This review provides theoretical foundation for precise controlling and adequate utilization of enzymes throughout the tea manufacture chains.