Analysis of differences in flavonoid compounds in tea using HPLC combined with multivariate statistical methods

Flavonoids are among the most sensorially active components in tea, and their content and taste characteristics are significantly influenced by processing techniques. This study optimized the extraction conditions for flavonoids and established an HPLC method for simultaneous detection of taxifolin, rutin, ellagic acid, myricetin, quercetin, luteolin, and kaempferol. Qualitative and quantitative analyses were conducted on these seven flavonoids, along with catechins and theaflavins, in six categories of commercially available teas. The results were subjected to Principal Component Analysis (PCA), yielding five principal components. Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) showed significant clustering within each of the six tea categories, with excellent separation between groups. Based on Variable Importance in Projection (VIP) values, 11 key differential markers highly correlated with tea processing methods were identified. This enables effective differentiation of the six tea categories, provides targets for tea quality regulation, and strengthens the application value of chemical space analysis in tea quality tracing. Subsequent research could further expand the sample size and analyze multi-factor interaction effects to build more accurate models with broader discriminative capability.