Characterisation of odorant compounds and their biochemical formation in green tea with a low temperature storage process

摘要

We produced low temperature (15 ℃) processed green tea (LTPGT) with higher aroma contents than normal green tea (Sencha). Normal temperature processed green tea (NTPGT), involved storing at 25 ℃, and Sencha had no storing process. Sensory evaluation showed LTPGT had higher levels of floral and sweet odorants than NTPGT and Sencha. Aroma extract dilution analysis and gas chromatography-mass spec-trometry-olfactometry indicated LTPGT had 12 aroma compounds with high factor dilution values (FD). Amongst LTPGT's 12 compounds, indole, jasmine lactone, cis-jasmone, coumarin, and methyl epijasmo-nate contributed to floral, fruity and sweet characters. In particular, indole increased initially, peaking at 16 h, then gradually decreased. Feeding experiments suggested [~(15)N]indole and [~(15)N]oxygenated indoles (OX-indoles) were produced from [~(15)N]anthranilic acid. We proposed the increase in indole was due to transformation of anthranilic acid during the 16 h storage and the subsequent decline in indole level was due to its conversion to OX-indoles.