Quality changes of Fuzhuan Tea during processing period based on principal component and cluster analysis

Ten time periods samples from processing process of Fuzhuan Tea were collected, and 18 quality component were measured.Principal component analysis and cluster analysis were used to investigate the quality component, the relationship between the sample and the quality component were constructed. The results indicated that major changed components in the processing of Fuzhuan Tea was EGCG, GCG, ECG, tea polyphenols, soluble sugars, gallic acid and water extracts. The contribution ratios of the three principal components were 56.45%, 26.29% and 8.46%.It could be concluded through cluster analysis that processing process of Fuzhuan Tea was divided into four stages. The first stage was the Maocha period, including the Maocha and the zeroth day of fungus growing.The second stage was the early stage of fungus growing, including the pilefermentation, the third and sixth day of fungus growing.The third stage was the late stage of fungus growing, including the 9th day, the 12 th day and the 15 th day of fungus growing.The fourth stage was the drying period of Fuzhuan tea, including the 18 th day, and the 22 th day of fungus growing.This study established a evaluation system to change the quality of the process during the processing of Fuzhuan tea, and determined the Fuzhuan tea processing time of the dividing line.