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Processing plays a decisive role in the flavor of steamed green tea (SGT), especially spreading, which is the basis of its taste formation. However, the effect of spreading time on the taste quality of 'Qiancha 1' (Camellia sinensis var. sinensis) steamed green tea (QSGT) has not been reported. In this study, fresh leaves from 'Qiancha 1' were made into SGTs after spreading at different times and evaluated using a chromatographic method combined with an electronic tongue (E-tongue) and sensory evaluation, using 'Huacha 1' (Camellia sinensis var. sinensis) steamed green tea (HSGT) as the control. Galloylated catechins were transformed to non-galloylated catechins more drastically in 'Huacha 1' than in 'Qiancha 1' during spreading. QSGT made from fresh leaves after 6 h of spreading was among the best with umami and mellow tastes in the sensory evaluation, and QSGT had higher bitter, astringent, umami, and sweet taste values than HSGT in the E-tongue evaluation. In QSGT, l-theanine, l-glutamate (Glu), (−)-epigallocatechin-3-gallate (EGCG), l-histidine (His), and l-methionine (Met) were the predominant compounds for umami, bitter, and astringent tastes, while in HSGT, l-theanine, Glu, EGCG, His, Met, and l-arginine (Arg) were predominant. The principal component analysis and orthogonal partial least squares discriminant analyzes further revealed that differences in the metabolism of polyphenols contributing to the formation of bitter and astringency tastes were essential indicators for distinguishing SGTs made from different spreading times and cultivars. Overall, this study provides an approach for the enhancement of taste in SGT using the personalized processing method for different tea cultivars. [ABSTRACT FROM AUTHOR]

The current method for processing bud yellow tea usually results in astringent taste that is not sufficiently yellowing. Therefore, two factors in the production phase that affect tea quality were studied: number of times the tea leaves undergo the yellowing process and predrying of leaves to reduce their water content before a second yellowing process. We then evaluated the colour and nonvolatile compounds of the produced tea. Results revealed that gallated catechins and the polyphenol–amino acid ratio decreased significantly, and the colour of the tea changed from green to yellow after two yellowing processes. Predrying leaves to a lower water content resulted in the accumulation of free amino acids and soluble sugars, and an increase in the brightness and yellow colour of tea infusion. Bud yellow tea with the highest taste evaluation score and yellowness was obtained when the leave samples underwent two yellowing processes and the water content in the leaves was 40%. [ABSTRACT FROM AUTHOR]

Summary: The effects of roasting treatment on sensory quality and related compounds in green tea were investigated. The combined application of roasting temperature and time 100 °C for 90 min, 120 °C for 60 min and 140 °C for 30 min achieved the most satisfying sensory quality. The HPLC analysis showed that the contents of cis‐catechins, bitter and umami amino acids reduced with increase in temperature, while the contents of trans‐catechins and soluble sugar increased with the temperature rise. The content of caffeine and sweet amino acids did not change significantly compared with untreated tea sample. The decrease in cis‐catechins, total polyphenols and bitter amino acids reduced the bitterness and astringency of the green tea, while the increase in total soluble sugars improved the sweetness and mellow taste. The sensory evaluation results showed that the sensory quality of the tea was significantly enhanced through roasting treatment. Roasting treatment significantly improved the sensory quality of green tea. [ABSTRACT FROM AUTHOR]