Abstract: Two classification methods for Pu′er raw materials were explored using principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), and the important physical and chemical compositions were identified through the statistical analysis. The results revealed that both PCA and PLS-DA could directly classify the grades of Pu′er raw materials, particularly for the grade 3, but not for that of grade 6 and 9. The PCA loadings plot and PLS-DA variable important for the projection plot indicated that the contents of amino acids were the important physical and chemical components for classification. Lysine (Lys), proline (Pro) and phenylalanine (Phe) were three most important physical and chemical compositions.

Key words: Pu′er raw materials tea;, grade classification, PCA, PLS-DA