Impact of enzymatic fermentation on taste, chemical compositions and in vitro antioxidant activities in Chinese teas using E-tongue, HPLC and amino acid analyzer. (15th June 2022)

• Record Type: Journal Article
• Authors: Zhou, Binxing; Ma, Bingsong; Xu, Chengcheng; Wang, Jiacai; Wang, Zihao; Huang, Youyi; Ma, Cunqiang
• Is Part Of: Lebensmittel-Wissenschaft + Technologie =. Volume 163(2022)
• Publication Date: 2022-06-15
• Subjects: White tea -- Electronic tongue -- Partial least squares-discriminant analysis -- Catechins -- ABTS scavenging ability; Food industry and trade -- Periodicals; Food -- Composition -- Periodicals; Microbiology -- Periodicals; Nutrition -- Periodicals; 664.005
• DOI: 10.1016/j.lwt.2022.113549
• Languages: English
• ISSNs: 0023-6438

Abstract

Abstract: Green, white and black teas showed different degrees in enzymatic fermentation through relevant processing procedures. To reveal the impact of enzymatic fermentation in tea-leaves, 44 chemical components including 17 phenolic compounds, 3 purine alkaloids, 19 free amino acids and γ-aminobutyric acid (GABA) in 27 various tea samples were determined by HPLC and amino acid analyzer, respectively. Additionally, E-tongue and 5 various assays were developed for taste evaluation and in vitro antioxidant activities analysis. Multivariate statistical analyses, such as PCA, HCA and PLS-DA (R 2 X = 1.000, R 2 Y = 0.932, Q 2 = 0.908, respectively) divided theses teas into green, white and black tea categories, indicating the profound impact of enzymatic fermentation on tastes and chemical compositions. The enzymatic fermentation highly significantly ( p < 0.001) promoted the decreases of 5 catechins (i.e. C, EC, GC, ECG and EGCG), gallic acid, rutin and 6 free amino acids, and the accumulations of 4 flavonoids (i.e. taxifolin, myricetin, queretin and luteolin), ellagic acid and 4 free amino acids in tea-leaves. The bivariate correlation analysis confirmed that 7 catechins, GG and 7 free amino acids might impress bitterness, umami and astringency, which also contributed to the antioxidant activities in tea-leaves. This study advanced the knowledge about enzymatic fermentation in tea-leaves processing. Highlights: Enzymatic fermentation caused the chemical differences among green, white and black teas. Enzymatic fermentation significantly impact 5 catechins, 5 flavonoids, 6 free amino acids. Slight enzymatic fermentation might improve the in vitro antioxidant activities in tea-leaves. Catechins, free amino acids contributed to antioxidant activities, bitterness, umami, astringency.