Main Microorganism And Quality Change Of Pu'er Tea During In Puer Tea Fermentation

The pile-fermentation is the key to the quality of Pu'er tea.The quality of primary tea,the environment and processing technology all have an important influence on the quality of Pu'er tea.The relationship between the environmental temperature and humidity,the moisture content of the product,the change of microbial population and the formation of the quality of the finished tea during the fermentation process of Pu'er ripe tea still needs in-depth study.In this study,we tracked and observed the fermentation process of multiple Pu'er tea fermented tea piles in the tea factory in Menghai County,and analyzed and tested the environmental factors and microorganisms that affect the fermentation.The purpose is to clarify the fermentation process of Pu'er tea.The changing law of microorganisms and quality components.Research indicates:(1)The moisture content of the fermented tea piles generally declines with the fermentation process,but it does not change much in the early stage of fermentation.The main water loss stage is after removing the cover after 20 days and drying it;(2)The temperature of the tea pile is bounded by turning the pile.The temperature during each fermentation cycle has experienced a rapid rise to a steady development process.In the first 20 days of fermentation,the temperature increased by about 8°C after the first turning,and it was maintained until the 20 th day.After the 20 th day of fermentation,the temperature of the tea pile tends to drop.In the subsequent drying stage,the temperature continues to be equal to room temperature.(3)During the process of worming,both tea polyphenols and catechins are greatly reduced with the progress of the fermentation process.Among them,only trace amounts of catechins are detected in the cooked tea,and there are 25% residual amounts of tea polyphenols.(4)Sensory evaluation of wet and dry samples during the fermentation process showed that the dried green tea should gradually form the quality and flavor of Pu'er ripe tea after being fermented.During the fermentation process,the product will have a more obvious sour taste.After the fermentation,the overall taste of the tea leaves slowly changes from astringent to mellow and smooth,and the aroma changes from the obvious fresh and floral aroma of dried green tea.The scent of mature Pu'er tea has a strong scent.The color of the tea soup turns from yellow to deep red after 20 days of fermentation,and the red gradually darkens.The texture and color of the leaf bottom have also gone from yellow-green to yellow-brown to brown-black and then appear.The process of a small amount of pig liver color.(5)The main microorganisms in the fermentation of Pu'er tea are yeast,Aspergillus tubingensis and Aspergillus aculeatus.There are also a small number of other microorganisms,such as Aspergillus aculeatus,Penicillium,etc.,but the most dominant position is yeast-tower.Compound action of Aspergillus.In the Pu'er tea heap stage,there is a certain regularity in the distribution and succession of microorganisms.In the first two days,yeast dominates,and a large number of them appear in the first day.The most vigorous period is before the first stage of fermentation.For three days,as the fermentation process progresses,the number of yeast will decrease until it is almost non-existent.After the vigorous reproduction of the first two days,the advantage of yeast will be replaced by Aspergillus tubingensis.The growth and development of Aspergillus tubingensis is almost accompanied by the entire process of Pu'er tea fermentation.It is the most widely distributed during the fermentation process,which has an impact on the quality of Pu'er tea.maximum.Aspergillus tubingensis thrives in tea piles with huge biomass.It mainly breeds within 15 cm of the surface of the tea pile and forms a double-layered structure inside and outside the tea pile.Aspergillus aculeatus exists in a very small area in the tea pile,and can only be found on the surface with good air permeability and low temperature,and it usually coexists with the main bacterial species.