UV-B application during the aeration process improves the aroma characteristics of oolong tea

Solar withering is essential for the aroma formation of oolong tea, but due to the rainy and humid weather in plantation areas, solar withering became insufficient which seriously limits high-grade oolong tea production. This study aims to investigate ultraviolet B (UV-B) effects on the aroma characteristics of oolong tea and its feasibility in improving tea aroma quality. Sensory evaluation, odorant quantitation, and aroma characteristic analysis suggested UV-B application during the aeration process provided similar effects as solar withering in improving the aroma quality of oolong tea. UV-B application significantly increased fruity and floral odorants (4-hexanolide, alpha-farnesene, and beta-ocimene by 44%, 74%, and 37%, respectively), and decreased green and fatty odorants (hexanal, (E)-2-octenal, and (Z)-4-heptenal by 42%, 45%, and 27%, respectively). These indicate UV-B is crucial for the flowery and fruity aroma formation of oolong tea, which can be potentially applied to oolong tea production, especially under unsunny weather.