A survey of the fluctuation of microorganisms in process of manufacturing Oolong tea

Abstract

The manufacturing process of Oolong tea was divided into 9 stages. The role of microorganisms in Kim Tuyen and Thuy Ngoc Oolong tea manufacturing was examined and the fluctuation of the total microbial volume was considered as indicators for assessment. Some of the representative microorganisms were identified. The results showed that some kinds of the bacteria, yeast and mold were detected in the whole stages. The density of the total microorganisms in each stage changed according to a certain rule. In Kim Tuyen’s tea leaves, the density of bacteria increased to its peak of 1.1x106 CFU/g in the 6th stage (after the 2nd aromatic spin), whereas, in Thuy Ngoc’s tea leaves, the density of bacteria increased to 6.3x105 CFU/g in the 7th stage (after the 3rd time of incubation). In PDA medium, the density of yeast was about 105 CFU/g while the density of filamentous fungi was too low. The identification results showed that two strains of yeast and bacterium were named Meyerozyma guilliermondii and Chryseobacterium taeanense.