Targeted metabolites analysis and variety discrimination of Wuyi rock tea by using a whole-process chemometric-assisted HPLC-DAD strategy

As the China’s top-ranked oolong tea, there are many varieties of Wuyi rock tea (WRT) in the market. The prices of different varieties vary greatly, and the differential chemical composition is unclear. Therefore, we developed a rapid and systematic chemometrics-assisted HPLC–DAD strategy for targeted metabolites analysis and variety discrimination of WRT. The strategy involved design of experiment , targeted metabolites quantification, varieties discrimination and differential component screening. Specifically, optimal extraction conditions of WRT are obtained by response surface methodology-Box-Behnken design method. Then, 22 targeted metabolites are rapidly and accurately quantified by alternate trilinear decomposition algorithm (ATLD) with average spiked recoveries ranging from 85.4% to 108.6%. Finally, the four WRT varieties (110 samples) are discriminated by linear discriminant analysis (LDA) and partial least squares-discriminant analysis (PLS-DA) with relative concentration results as model input. The correct classification rates obtained by PLS-DA are greater than 88%, especially for high-quality “Niulankeng rougui” tea, its specificity and sensitivity are 100%. Moreover, ten differential metabolites related to identification are screened by variable importance in projection (VIP). This work scientifically and comprehensively elaborates the whole-process of WRT analysis, which can become a comprehensive food analysis strategy for the purpose of precise quantification and pattern recognition.