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Soluble sugar is one of the important characteristic metabolites contributing to the flavor quality of tea. However, little is known about the changes and metabolic pathways of sugar in summer–autumn black tea varieties during the solid-state fermentation of Ganoderma lucidum. Therefore, this study is aimed at investigating the effects of the solid-state fermentation of Ganoderma lucidum on soluble sugar metabolism in three summer–autumn black tea varieties. In this study, we combined targeted metabolomics technology, gas chromatography-mass spectrometry, and multivariate statistical analysis to reveal the metabolic rules of 13 different sugars in three varieties of summer–autumn black tea under the action of Ganoderma lucidum. Using multivariate statistical analysis, 8 common key sugar differential metabolites were selected from the three groups of samples: D-fructose, trehalose, lactose, maltose, D-galactose, glucose, L-rhamnose, and xylitol. The eight different sugars contributed to the quality difference between Ganoderma lucidum tea and black tea in this study. To better explore the patterns of sugar changes, the metabolic pathways of 13 different sugars were screened and analyzed. The result revealed that the solid-state fermentation of Ganoderma lucidum increased the sweet characteristics and decreased the bitter characteristics of the three summer–autumn black tea varieties. In addition, these results showed that the solid-state fermentation of Ganoderma lucidum could produce lactose in tea, reduce glucose and fructose contents, and increase xylitol content. The solid-state fermentation of Ganoderma lucidum can regulate soluble sugar metabolism in three summer–autumn black tea varieties, leading to an improvement in their quality. This study has potential practical significance for regulating the flavor quality of summer–autumn tea. [ABSTRACT FROM AUTHOR]

Jinmudan (JM) tea, produced using Camellia sinensis, cultivar JM, is popular among consumers because of its strong floral and fruity aroma. Aroma profiles of white, green, black, and oolong teas, which were obtained from JM and Tanyangcaicha (TY, control and indigenous variety), were investigated. Sensory evaluation was used to describe the quality characteristics of the tea samples. A combination of headspace solid-phase microextraction, gas chromatography–mass spectrometry (HS-SPME/GC–MS), and chemometrics was used to extract and analyze the volatiles in the samples; 162 volatiles were identified and categorized on the basis of their chemical structures. The proportions of chemical categories differed among the teas. The same type of tea obtained from JM and TY differed significantly in concentrations and categories of volatiles. This study will improve our understanding of the profile of volatile compounds in JM teas and create a basis for investigating the biological characteristics of JM teas. [ABSTRACT FROM AUTHOR]

• Different withering methods affect the aroma quality of Keemun black tea. • Sun withering significantly enhanced the floral and fruity of Keemun black tea. • Methional, geraniol and linalool are the most active-aroma in Keemum black tea. • A more comprehensive profile of Keemun aroma was obtained. Withering is a key process that affects the aroma of Keemun black tea (KBT). In this study, the aroma composition of KBT through natural withering, sun withering, and warm-air withering was analysed using gas chromatography–mass spectrometry. The results revealed significant differences in the three samples. Gas chromatography–olfactometry and aroma extract dilution analysis were performed with screening through a relative odour activity value (rOAV) > 1. In total, 11 aroma-active compounds (geraniol, (Z)-4-heptenal, 1-octen-3-ol, (E)- β -ionone, 3-methylbutanal, linalool, β -damascenone, (E , E)-2,4-decadienal, methional, (E , E)-2,4-nonadienal, and (E)-2-nonenal) were found to be responsible for the differences in aroma caused by different withering methods. Linalool (rOAV, 161) and geraniol (rOAV, 785) were responsible for the higher flowery and fruity aromas when sun withering was applied, whereas methional (rOAV, 124) contributed to the intense roasty aroma when warm-air withering was employed. Moreover, our results were verified by quantitative descriptive analysis and addition experiments. [ABSTRACT FROM AUTHOR]