Impact of ecological shading on the quality of Lushan Yunwu summer tea

Lushan Yunwu Tea (LSYWT) is one of China’s renowned green teas. As an approach to sustainable ecological management, ecological shading has been scarcely studied in terms of its influence on the quality of LSYWT. In this study, tea trees that are grown in monoculture (CK), with partial shading (ES1), and with full shading (ES2), were selected to investigate how ecological shading affects flavor substances and aroma components of tea. Our findings indicate that catechins, caffeine, and theobromine were significantly increased under ES1 and ES2, and the total amounts of umami and sweet amino acids, as well as bitter amino acids, were highest in ES1. The taste activity value (TAV) of aspartic acid, glutamic acid, and theanine, which are related to umami, were highest in ES1, while the taste activity value of arginine, associated with astringency, was highest in CK. A total of 85 volatile compounds were identified across CK, ES1, and ES2. The results indicated that cis-jasmone, indole and cis-3-hexenyl hexanoate were characteristic aroma compounds of ES1. This study demonstrates that fresh tea leaves cultivated under ecological shading (ES1) conditions can be processed into LSYWT exhibiting characteristic chestnut-like aroma and floral notes, accompanied by significantly reduced bitterness.