Modeling for the dry tea and soup color comprehensive evaluation of yellow tea at the different Yellowing time

An suitable comprehensive evaluation method for dry tea and soup color of yellow tea at the different Yellowing time was established,which help to choose the best yellowing time.Principal component analysis( PCA)and hierarchical cluster analysis( HCA) were applied to analyze Physical and chemical index of eighteen yellow teas.The first six components represented 83.45% of the total variability,and a color mathematical evaluation model was constructed: Y = 0.671PC1 + 0.218PC2 + 0.111PC3.The results of the mathematical evaluation model on eighteen yellow tea samples were highly consistent with sensory evaluation and hierarchical cluster analysis( HCA) results.That meant the mathematical evaluation model was reliable.