不同发酵时间与足火干燥工艺对红茶理化品质的影响OA

[Objective]This study aimed to investigate the effects of different fermentation time and second-drying technologies on the quality of black tea processed from the Longjing 43 tea variety,providing reference for efficient de-velopment and utilization of Longjing 43 tea variety,as well as black tea processing technology optimization.[Method]One bud and two leaves of Longjing 43 variety were taken as raw materials.High-performance liquid chromatography and headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry were utilized to investigate the differences in physicochemical components,catechin components,and volatile components of black tea under diffe-rent fermentation time and second-drying technologies.[Result]After 2 h of fermentation,the tea polyphenol content reached 18.41%,with theaflavin and soluble sugar peaking at 1.90%and 3.03%respectively.Under second-drying at 80℃for 1.5 h followed by an increase to 90 ℃ for 20 min(LG89),the theaflavin content of black tea was 1.22%,tea polyphenol was at the lowest(10.53%),and soluble sugar content peaked at 4.00%.Prolonged fermentation resulted in a significant decrease in gallic acid content,catechin component content,and theobromine content.In contrast,the LG89 variable-temperature second-drying technology demonstrated a significantly higher retention of gallic acid,epigallocatechin gallate(EGCG),and total ester catechins compared to the other three second-drying technologies(P<0.05).Principal component analysis,orthogonal partial least squares discriminant analysis,and cluster heatmap analysis revealed that,soluble sugar,theaflavin,caffeine,total alkaloid,and tea polyphenol were the key components contributing to quality differences in black tea due to fermentation time;theaflavin,epicatechin(EC),tea polyphenol,EGCG,and total ester catechins were identified as the key components influencing quality differences in black tea resulting from the second-drying technologies.A total of 30 key aroma components were identified in the samples under different fermentation time and second-drying technologies.With an increase fermentation time,the content of volatile components such as alcohols,heterocyclic compounds,and esters increased;fermentation for 2 h led to linalool content of 26.05 μg/g and the highest content of(3Z)-hex-3-en-1-ol of 2.49 μg/g.The second-drying at 70℃was found to better preserve volatile sub-stances,as total content of 30 key volatile components and contents of alcohols and heterocyclic compounds were higher compared to the other three second-drying technologies.The contents of linalool and ethyl 2-(5-methyl-5-vinyltetrahy-drofuran-2-yl)propan-2-yl carbonate reached the highest,which were 25.72 and 22.90 μg/g respectively.[Conclusion]When using fresh leaves with one bud and two leaves of Longjing 43 to process black tea,the taste and aroma quality fer-mented for 2 h are better;second-drying at 80℃for 1.5 h followed by drying at 90℃for 20 min yields better taste for black tea;second-drying at 70℃leads to better aroma of black tea.