RESUMEN
High mountain tea (HT) is widely acknowledged as an essential resource of high-quality tea due to its adaptation to superior ecological environments. In this study, the sensory (aroma and taste) and safety (heavy metals and pesticide residues) characteristics of HT were characterized through sensory evaluation, gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), flavor activity value, and risk factor analysis. The results elucidated that the aroma sensory characteristics of HT were tender and green, accompanied by sweet and slight chestnut. A total of 8 aroma compounds were identified as the primary substances contributing to the unique aroma characteristics; the difference in the ratio of "green substances" and "chestnut substances" might be the reason for different aroma characteristics in HT and LT (low mountain tea). The taste sensory characteristics of HT were high in freshness and sweetness but low in bitterness and astringency. The high content of soluble sugar (SS), nonester catechins, sweet free amino acids, and low content of caffeine and tea polyphenols were the primary reasons for its taste characteristics. Low temperature stress might be the most fundamental reason for flavor characteristics formation in HT. Furthermore, the pollution risks of 5 heavy metals and 50 pesticide residues in HT were less than 1. The complex ecosystem and low chemical control level were speculated to be the primary reasons for the high safety quality of HT. Overall, these findings provide a more comprehensive understanding of quality characteristics and their formation mechanisms in HT.
RESUMEN
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.
RESUMEN
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.