Studies On The Yellowing With Piling Process And The Effect Of Microorganisms On The Yellow Tea

Yellow Tea is one of the six major types of tea with unique quality in our country. Its basic process is fixing-yellowing-drying, among which the special yellowing process form the "yellow" quality:dry tea golden,liquor color bright yellow, the bottom yellow. The key " yellowing" process is selected as the research focus in this study. Optimization of "yellowing" process, isolation and identification of microorganisms in the process of "yellowing" and the maiden discussion of the effect of microorganisms on the Yellow Tea, all the above aim to provide theoretical guidance for the mechanized production and innovation of Yellow Tea.In order to investigate the effect on the Yellow Tea of different oxygen supply, in this experiment, the same amount of rolled leaves are put in three airtight containers. After vacuumising each container and then filled them with nitrogen, air and oxygen respectively for yellowing process. Results showed that sample of optimal quality is the one in the container filled with oxygen, which means that oxygen has a certain influence on the formation of the quality of Yellow tea during the yellowing process.Exploring the effect of the sequence of two processes:yellowing and rolling, on the quality of Yellow Tea, based on actual production operation. Results indicate that the experiment group which follows the order that first rolling then yellowing helps the formation of good colour and taste of the Yellow Tea.An orthogonal experimental of3factors and3levels is designed in yellowing process under the condition of mechanical processing, and then selecting the optimal parameter: water content-45%, yellowing temperature-35℃, yellowing time-8h.Study on the microbial groups during the yellowing process shows that the total amount of Fungus that were sampled, isolated and purified in different period is6, which consists of2strains of Aspergillus,2strains of Penicillium,1strain of Trichoderma,1strain of Yeast and1strain of other Aspergillus. Afterwards, set two contrast groups at30℃and40℃under sterile yellowing condition and traditional yellowing condition separately. Results indicate that different yellowing temperature and yellowing time shows considerable influence on the formation of the quality of Yellow Tea whereas microorganisms do not. In other words, effect of humidity and temperature on the quality of Yellow Tea far outweighs that of microorganisms.