Insight into the effect of cultivar and altitude on the identification of EnshiYulu tea grade in untargeted metabolomics analysis

• Published in: Food chemistry 2024-03, Vol.436, p.137768-137768, Article 137768
• Main Authors: Zou, Dan, Yin, Xiao-Li, Gu, Hui-Wen, Peng, Zhi-Xin, Ding, Baomiao, Li, Zhenshun, Hu, Xian-Chun, Long, Wanjun, Fu, Haiyan, She, Yuanbin
• Format: Article
• Language: English
• Subjects: Grade discrimination; Green tea; Metabolomics; UPLC-Triple-TOF/MS
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2023.137768

•The effect of variety and elevation on the identification of ESYL tea grades was explored.•Variety differences outweighed elevation differences, hiding the differences in grade.•14 common grade differential compounds were identified for Longjing 43 samples.•4 compounds presented same distribution trend related to tea grade, independent altitude.•A robust and generalized tea grade evaluation model was established. The accurate identification of tea grade is crucial to the quality control of tea. However, existing methods lack sufficient generalization ability in identifying tea grades due to the effect of temporal and spatial factors. In this study, we analyzed the effect of cultivar and altitude on EnshiYulu (ESYL) tea grades and established a robust model to evaluate their quality. Principal component analysis (PCA) revealed that differences in variety and elevation can mask grade differences. Orthogonal projection to latent structure-discriminant analysis (OPLS-DA) was used for grade identification of samples from different altitudes. For ESYL tea samples above and below 800 m altitude, 75 and 35 grade differentiated metabolites were discovered, with 14 common differentiated metabolites. Based on reconstructed OPLS-DA models, the grades of multi-altitude sources ESYL were discriminated with a rate > 85%. These results demonstrate the potential of a grade discrimination model based on common differential metabolites, which exhibits generalization ability.