Widely targeted metabolomic analysis reveals metabolite changes induced by incorporating black tea fermentation techniques in oolong tea processing for quality improvement

• Published in: Food chemistry Vol. 459; p. 140433
• Main Authors: Hao, Mengjiao, Lai, Xingfei, Li, Qiuhua, Cao, Junxi, Sun, Lingli, Chen, Ruohong, Zhang, Zhenbiao, Li, Qian, Lai, Zhaoxiang, Sun, Shili
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 30.11.2024
• Subjects: Astringency; Oolong tea; Short fermentation; Widely targeted metabolome; Wrap-rolling; GC–MS/MS; Astringency; EI; FO-H; Wrap-rolling; HCA; OPLS-DA; rOAV; Short fermentation; FO-L; PCA; TIC; QC; CV; Oolong tea; BTF; SIM; Widely targeted metabolome; OT-IBTFT; UPLC-MS/MS; KEGG; ESI; VIP; FC
• ISSN: 0308-8146; 1873-7072; 1873-7072
• DOI: 10.1016/j.foodchem.2024.140433

Oolong tea, a semi-fermented tea, has a prominent fruity and floral aroma, resembling green tea's astringency and pungency but lacking black tea's mellowness. Oolong tea incorporating black tea fermentation techniques (OT-IBTFT) not only retained its excellent floral and fruity aroma but also reduced astringency and enriched taste. However, metabolite changes remain unknown. In this study, widely targeted metabolomic analysis showed OT-IBTFT reduced prunin, gallocatechin, methyl gallate, and increased loliolide by changing the flavonoid biosynthesis and biosynthesis of secondary metabolites pathways, thereby reducing the astringency and increasing the mellow taste and richness to improve oolong tea quality. In addition, Wrap-rolling 5 times increased fermentation, improving the color and aroma of oolong tea by increasing theaflavic acid and 2-furoic acid, is more significant than wrap-rolling once. In conclusion, these findings provide a theoretical basis for the improvement of oolong tea processing techniques and flavor and quality control. [Display omitted] •Fermenting oolong tea like black tea notably enhances its quality.•Fermenting oolong tea keeps floral, fruity aromas and cuts astringency for a mellow taste.•Prunin, gallocatechin, methyl gallate reduced the astringency of fermenting oolong tea.•Wrap-rolling boosted fermentation, enhancing color and aroma by higher theaflavic and 2-furoic acids.