Association between chemistry and taste of tea: A review

Taste is an important factor in evaluating the quality of tea. The sweet and umami tastes are usually well-accepted for consumers, whereas the bitter and astringent tastes are usually undesired, but they are important for providing the complex sensory perceptions of Camellia teas. The compounds responsible for the bitterness and astringency in tea leaves can be modified by processing, and subsequently endowed different taste of various tea types. Therefore, the taste of tea is closely related to the chemical constituents, and the taste mechanism is critical for improving tea quality. The aim of this review is to review and discuss the association between chemical composition of Camellia teas and their effects on bitterness, astringency, sweetness aftertaste and umami. In the tea infusion, flavonol-O-glycosides, tannins and galloylated catechins are the main astringent compounds, caffeine and non-galloylated catechins enhance the tea bitterness. Furthermore, l-theanine, succinic acid, gallic acid and theogallin contribute to the umami taste. Sweetness aftertaste is a unique perception of green tea, which is attributed to the hydrolysis of galloylated catechins. T1R2 and T1R3 have been identified as sweet and umami taste receptors, while T2Rs functionas the bitter taste receptor.