Study On The Effect On Quality Formation Of The Main Microorganisms During The Second Pile-fermentation In Anhua Raw Dark Tea

The Anhua raw dark tea is decided on the finished tea product. To improve the quality of Anhua dark tea, someone tries to carry out the second pile-fermentation on raw dark tea to promote its colour, aroma and taste, which makes flavours easy to accept for the customers. But there is not any systemic research reports on the second pile-fermentation.This study were finished on the basis of previous research in the laboratory for second pile-fermentation, combining physical and chemical analysis, sensory evaluation, microbiological analysis and extracellular enzyme activity analysis, to explore the role of second pile-fermentation and determine the optimum process conditions of second pile-fermentation, providing a theoretical basis for the promotion of raw dark tea quality improvement.By the system study, the results were as follows:1.It discussed the water content, fermentation time, air humidity in the second pile-fermentation and results showed that the second pile-fermentation had a promoting effect on raw dark tea. Especially in the amount of 35% water content, fermentation time 30h, under the conditions of air humidity of 85%, the best significant effect will change in the quality. Such as the colour of appearance turned green brown to brown, the light orange soup changed to bright orange, the aroma with pine smoke and little tart flavor turned to pure tea flavor, the taste with astringent became a more mellow flavor and the leaves after brewing turned green and yellow to brown.2.It explored the procedures and reasons in the changes of raw dark tea with second pile-fermentation in factory and laboratory. Detection of microbiological analysis in the two different conditions of second pile-fermentation showed the advantage microorganism were Aspergillus niger, Penicillium, yeasts and Bacillus. The differences between the two conditions were the different yeast populations and the structures and populations of microorganism. In factory, the advantage microorganism was the Aspergillus niger in the earlier stage while in the later stage were the yeasts in the second pile-fermentation. But the Aspergillus niger are the main advantage microorganism in the whole process of second pile-fermentation in the laboratory. And the populations of the advantage microorganism in the former condition were much more than the latter, which also lead the enzymatic activitives higher secreted by microorganism in the second pile-fermentation. The transformation of the ingredients in factory raw dark tea were intenser, especially polyphenols, flavonoids, soluble sugar, catechin group and the total amounts about flavor, which are decreasing faster and more to make quality changes faster.3.It explored the influence of inoculation with different microorganism in second pile-fermentation and the changes of raw dark tea quality. The structures and populations of microorganism were changed by inoculating with different microbes during the second pile-fermentation. The result showed that different microorganism had competitive and inhibitory relationship in this process. A certain amount of Aspergillus niger could inhibit the growing of penicillium, yeasts; and a quantity of penicillium could inhibit the growing of aspergillus niger, yeasts and Bacillus. Inoculating different microorganism had the same main effect on raw dark tea, only the dgrees were diverse. The more aspergillus niger in the process, the more polyphenols, catechin components and total contents transformed. The inoculation of mixed bacteria on the tea made a better sensory quality than that of the single bacteria. And it could shorten the purifying time of raw dark tea with bacteria inoculated for second pile-fermentation.