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.

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.