This study aimed to evaluate the dynamic changes of non-volatile metabolites during green tea processing from the albino tea variety ‘Fuhuang 1’. Green tea was made from one bud with two leaves through three steps: natural drying, fixation and rolling. A total of 2654 non-volatile metabolites were detected by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) in the raw material, intermediate products and final product. The total content of non-volatile metabolites showed an upward trend during tea processing. Our analysis showed that fixation was crucial for the conversion of non-volatile metabolites in green tea processing. A total of 292 important differential metabolites were selected before and after fixation, including amino acids and their derivatives (40), flavonoids (37), lipids (101), nucleotides and their derivatives (28), and phenolic acids (21). These metabolites were significantly enriched in pathways such as the biosynthesis of secondary metabolites, carbon metabolism, cysteine and methionine metabolism, arginine biosynthesis, alanine, aspartic acid and glutamic acid metabolism. They were categorized into three clusters by K-Means analysis. The metabolites in the first cluster accumulated significantly during fixation. The metabolites in the second cluster accumulated significantly during fixation and also accumulated during drying, but to a lesser extent. However, the metabolites in the third cluster significantly decreased during fixation. Amino acids and their derivatives accumulated significantly during fixation, especially reduced glutathione, which might be a signature compound of ‘Fuhuang 1’ green tea. Lipids were the most active compounds during green tea processing; their relative contents significantly increased, with lysophosphatidylethanolamine showing the greatest accumulation. Some flavonoids, nucleotides and their derivatives accumulated only during fixation, whereas others accumulated during both fixation and drying. This study provides a theoretical basis for the innovative utilization of tea albino mutants.

The aroma components of white tea from the new tea strain ‘Baiyun 0492’ (also known as Baiyun Tezaocha) and ‘Fuyun 6’ as a control were analyzed and compared by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) in an effort to identify the characteristic aroma components of ‘Baiyun 0492’ white tea. A total of 928 aroma compounds were detected in six white tea samples (of three different grades for each type), and nonyl acetate, contributing to floral and fruity aromas, might be an aroma compound unique to ‘Baiyun 0492’ tea. The results of relative odor activity value (ROAV) analysis showed that β-ionone, linalyl acetate, linalool, (Z)-decan-2-enal, damascenone, neral and citral were the key aroma components in both white teas. Based on orthogonal partial least squares-discriminant analysis (OPLS-DA), the contents of linalool, methyl benzoate, hotrienol, nonyl acetate, 3,7-dimethy-6-actenoic acid and geranyl formate in ‘Baiyun 0492’ tea were significantly higher than those in ‘Fuyun 6’ tea (variable important in the projection (VIP) > 1, P < 0.05). Linalsol and methyl benzoate were important aroma compounds of ‘Baiyun 0492’ white tea, responsible for pekoe-like, fruity and floral aromas. This study is helpful for a comprehensive understanding of the aroma characteristics of ‘Baiyun 0492’ white tea, and provides a scientific basis for the research and development of ‘Baiyun 0492’ white tea products with distinctive personality.

This study aimed to evaluate the characteristic aroma compounds of white tea made from ‘Fuhuang 1’, an albino mutant of ‘Fuandabaicha’, and their dynamic changes during tea processing. The types and relative contents of volatile compounds in ‘Fuhuang 1’ and ‘Fuandabaicha’ tea leaves withered for 0, 12, 24, 36 and 48 h and in white tea made from each variety were determined by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). A total of 560 aroma compounds were detected in all samples, among which terpenes, heterocyclic compounds, esters and hydrocarbons were the major aroma components of white tea. During the withering process, the total content of volatile metabolite in both cultivars gradually increased, reaching the highest value at 48 h. Based on their relative odor activity values (ROAVs), terpinolene, citral, 1-octen-3-one, and damascenone were identified as the key aroma components of ‘Fuandabaicha’ white tea, and these compounds together with methyl salicylate and benzaldehyde as the key aroma components of ‘Fuhuang 1’ white tea. 1-Octen-3-one and citral were accumulated in large amounts at the early stage of withering and then decreased. Terpenolene, benzaldehyde, methyl salicylate, and damascus ketone continuously increased during the whole withering process. Terpinolene, citral, 1-octen-3-one, and damascenone greatly contributed to the floral, fruity and sweet aroma of ‘Fuhuang 1’ and ‘Fuandabaicha’ white tea. 1-Octene-3-one, methyl salicylate, and benzaldehyde were the key compounds responsible for the clean and fresh aroma of ‘Fuhuang 1’ white tea. This study helps gain insights into the aroma characteristics of ‘Fuhuang 1’ white tea and provides a scientific basis for the research and development of white tea made from albino tea plant mutants.

Taste is an important quality attribute of tea. In order to find out the taste quality of green teas made from the major varieties in Wanzhou district, Chongqing, the taste profile of the tea infusions was determined by sensory evaluation and 5 taste components including catechins, free amino acids, alkaloids, flavanols and their glycosides, and organic acids were analyzed by targeted detection methods. The results showed that there were obvious differences in the taste quality of green teas prepared from the 4 varieties of tea trees. Sichuan middle-and small-leafed tea group variety had a strong taste, and ‘Anji Baicha’ had an obvious fresh and brisk taste with mellow sweet aftertaste. ‘Fuding Dabaicha’ tasted strong with fresh and brisk taste and mellow sweet aftertaste. ‘Zhonghuang 1’ tasted fresh and brisk but less strong. The results of taste component analysis showed that the Sichuan middle-and small-leafed tea group variety contained high contents of catechins but low contents of free amino acids. ‘Anji Baicha’ had the highest content of free amino acids. The content of each flavor component was high in ‘Fuding Dabaicha’, and the contents of total flavor components and water extract of ‘Zhonghuang 1’were low. The results of principal component analysis (PCA) showed that the 4 varieties could be well distinguished. Thirteen major taste contributors such as rutin and caffeine were identified. The differential analysis indicated that aspartic acid, glutamic acid and theanine were the major contributors to the fresh and brisk taste characteristics of ‘Anji Baicha’and ‘Fuding Dabaicha’. Yangmeiin-3-O-galactoside and chrysin were the major taste contributors for ‘Zhonghuang 1’ that distinguished it from the other 3 varieties. There were also large differences in taste components within the Sichuan middleand small-leafed tea group variety, with samples C4 and C5 being closer to each other. They both contained high contents of flavonoid glycosides, having a strong astringent taste. This study provides a reference for research to improve the flavor quality of green tea in Wanzhou district.