No abstract

cis-3-Hexen-1-ol has been regarded as the main source of green aroma (or green odor) in green tea. However, no clear findings on the composition of green aroma components in tea and the effect of cis-3-hexen-1-ol on other aroma components have been reported. In this study, the main green aroma components in green tea were characterized, especially the role of cis-3-hexen-1-ol in green aroma was analyzed and how it affected other aroma components in green tea was studied. Based on the GC–MS detection, odor activity value evaluation, and monomer sniffing, 12 green components were identified. Through the chemometric analysis, cis-3-hexen-1-ol was proven as the most influential component of green aroma. Moreover, through the electronic nose analysis of different concentrations of cis-3-hexen-1-ol with 25 other aroma components in green tea, we showed that the effect of cis-3-hexen-1-ol plays a profound effect on the overall aroma based on the experiments of reconstitution solution and natural tea samples. GC–MS and CG-FID confirmed that the concentration range of the differential threshold of green odor and green aroma of cis-3-hexen-1-ol was 0.04–0.52 mg kg−1.

Sour is an important taste in some foods, beers, and teas; organic acids, in particular, are thought to play a key role in the formation of the sour taste of beer. It has been generally thought that organic acids also contribute to some teas tasting sour. In this study, through sensory evaluation experiments with black tea (BT) and green tea (GT), the difference in the sour taste of BT and GT was quantitatively characterized. Then the organic acids in the two types of tea were identified and quantified via high‐performance liquid chromatography (HPLC) with taste activity value (TAV) analysis. The results showed that both teas had 12 identical common organic acids (including 11 taste‐active components), but the results of the TAV analysis were not consistent with those of the sensory evaluation. Therefore, there is no direct relationship between organic acids and the acidity in BT and GT. It is related to the interaction between organic acids and other substances, pH value, or other sour substances in tea infusions. The mechanism of the disappearance of sourness in tea infusions was also discussed. These results help us to understand the correlation between tastes in teas.

China, there is a common saying that "high mountain clouds make good tea," which means tea from high-altitude areas usually has excellent quality. High mountain tea (HT) refers to the tea produced in high-altitude mountainous areas, where the ecological environment is generally superior, with low temperature, less sunlight, and more clouds. Tea in these mountainous areas generally grows slowly but is rich in flavor substances (

High mountain tea(HT)is an important resource for high quality tea because of its superior ecological environment and rich contents. In this study, we used sensory evaluation, gas chromatography–mass spectrometry(GC-MS), liquid chromatography-mass spectrometry(LC-MS), flavor activity value and risk factors to characterize the flavor (aroma and taste) and safety (heavy metals and pesticide residues) characteristics of HT, and then combined with the production process and environmental conditions to explore the reasons for its quality formation. The results showed that, the aroma sensory characteristics of HT were tender and green, accompanied by sweet and slight chestnut. 8 aroma compounds were identified as the important contributing substances to aroma characteristics and the high ratio of " green substances " and "chestnut substances " was the main reason for its unique aroma characteristics. The taste sensory characteristics of HT were high in freshness and sweetness, low in bitterness and astringency. High content of soluble sugar, non ester catechins, sweet free amino acids and low content of caffeine and tea polyphenols are the main reasons for its taste characteristics. Low temperature stress is the most fundamental reason for the formation of flavor characteristics of HT. In addition, the pollution risks of HT of 5 heavy metals and 50 pesticide residues are all less than 1. The complex ecosystem and low level of chemical control are the main reasons for the high safety quality of HT. All in all, these findings enable us to have a more comprehensive understanding of the quality characteristics and formation reasons of HT.