Improving the flavor of summer green tea (Camellia sinensis L.) using the yellowing process.

Summer green tea (SGT) has poor flavor due to its high levels of bitterness and astringency. The present study aimed to improve the flavor of SGT using the yellowing process. The results showed that after the yellowing process, the sweetness and overall acceptability increased, and the content of gallated catechins and flavonol glycosides decreased by 30.2% and 27.4%, respectively, as did the bitterness and astringency of SGT. Yellowing caused a decrease in the concentration of some aroma compounds, such as (z)-3-hexen-1-ol, 1-hexanol, pentanal, heptanal and 1-octanol, which caused grassy, floral and fruity aromas. In contrast, the concentrations of 1-octen-3-ol, benzene acetaldehyde and ß-ionone increased, which have mushroom and sweet aromas. Meanwhile, the sweetness and umami of SGT were enhanced by the addition of selected aroma compounds (1-octen-3-ol, benzene acetaldehyde and ß-ionone), demonstrating that the yellowing process improves the flavor of SGT through odor-taste interactions.

Aroma profiles of green tea made with fresh tea leaves plucked in summer.

There is a claim that fresh tea leaves plucked in summer (FTL-S) are not suitable for green tea processing, but there is no scientific evidence to support this claim. The aroma properties of green tea (GT-S) made with FTL-S were studied by the analysis of volatiles during process, coupled with odor activity value (OAV) determination. The odor profiles of dry tea and tea infusion were investigated by sensory evaluation. The GT-S contained higher proportions of alcohols, alkenes and heterocyclic compounds with strong fragrance and nutty odors as well as moderate floral odor in comparison with FTL-S. ß-Damascenone and 2-ethyl-3,5-dimethylpyrazine with the OAV of 54,290 and 1.15, respectively, were the aroma-active compounds imparting woody and nutty odors in GT-S, respectively. Current study provides an alternative way to use FTL-S for green tea production, and we also found that L-theanine is an important aroma precursor for the formation of green tea aroma.