Affiliation:
1. Tea Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology, Genetics and Breeding of Special Economic Animals and Plants Ministry of Agriculture and Rural Affairs Hangzhou China
2. Graduate School of Chinese Academy of Agricultural Sciences Beijing China
3. Bioactivity and Applications Lab, Department of Biological Sciences, School of Natural Sciences Faculty of Science and Engineering University of Limerick Limerick Ireland
4. Zhejiang University Tea Research Institute Hangzhou China
5. Department of Food Science and Technology National University of Singapore Singapore Singapore
Abstract
AbstractTea is the second largest nonalcoholic beverage in the world due to its characteristic flavor and well‐known functional properties in vitro and in vivo. Global tea production reaches 6.397 million tons in 2022 and continues to rise. Fresh tea leaves are mainly harvested in spring, whereas thousands of tons are discarded in summer and autumn. Herein, pruned tea biomass refers to abandon‐plucked leaves being pruned in the non‐plucking period, especially in summer and autumn. At present, no relevant concluding remarks have been made on this undervalued biomass. This review summarizes the seasonal differences of intrinsic metabolites and pays special attention to the most critical bioactive and flavor compounds, including polyphenols, theanine, and caffeine. Additionally, meaningful and profound methods to transform abandon‐plucked fresh tea leaves into high‐value products are reviewed. In summer and autumn, tea plants accumulate much more phenols than in spring, especially epigallocatechin gallate (galloyl catechin), anthocyanins (catechin derivatives), and proanthocyanidins (polymerized catechins). Vigorous carbon metabolism induced by high light intensity and temperature in summer and autumn also accumulates carbohydrates, such as soluble sugars and cellulose. The characteristics of abandon‐plucked tea leaves make them not ideal raw materials for tea, but suitable for novel tea products like beverages and food ingredients using traditional or hybrid technologies such as enzymatic transformation, microbial fermentation, formula screening, and extraction, with the abundant polyphenols in summer and autumn tea serving as prominent flavor and bioactive contributors.