Abstract:Effect of different process conditions on microbes (mould) and enzyme activities(polyphenol oxidase, cellulase and pectinase) during the pile-fermentation of Pu-erh tea was studied by orthogonal experiment in laboratory-scale. During pile-fermentation process, mould was growth in large number at the beginning then remained stable. Polyphenol oxidase exhibited 3 kinds of trends which were increase-less-increased, decreased after increasing and increase-less-increase-less. Cellulase and pectinase exhibited similar change trend that was decreased after increasing with various peak value and appearance time. In addition, mould and enzyme activities were remained at a high level by initial moisture content controlled in the range of 40% to 45%. There was no effect on mould and enzyme activities by pH modification. Mould was remained at a high level by turning intervals in 8 days and enzyme activities were remained at a high level by turning intervals in 6 days. Based on the contents of theabrownin, tea polyphenol and catechins, it indicated that Puerh tea would be excessive oxidation under high level initial moisture content (50%) and too high or too low turning interval frequency(4 d, 8 d). Therefore, proper process will benefit the quality improvement of Pu-erh tea.
