Study On Flavor Quality Of Pu-erh Tea Fermented By Monascus And Yeast

Microorganism plays a key role in the fermentation process of Pu-erh tea,and is very important to form the unique flavor and quality of Pu-erh tea.Monascus fermentation of Pu-erh tea will produce unique koji ester fragrance,and yeast fermentation of Pu-erh tea tastes sweet and mellow.However,the previous research is to inoculate and ferment Pu-erh tea with Monascus or yeast.This paper is the first time to use Monascus and yeast to ferment Pu-erh tea,in order to explore the impact of mixed fermentation on Pu-erh tea and improve the flavor and quality of Pu-erh tea.Developed a characteristic flavor of Pu-erh tea.In this paper,the same kind of sundried green tea was used for 4 different treatments:Natural fermentation without exogenous microorganisms,Monascus fermentation with Monascus,yeast fermentation with yeast,mixed fermentation with Monascus and yeast were carried out.The sensory evaluation and physicochemical determination were carried out on the fermented Pu-erh tea.The volatile metabolites and odor activity value(OAV)were determined by GC-MS technology to screen the key aroma substances in the mixed fermentation process.The results are as follows:1.Natural fermented Pu-erh tea has rich aroma and sweet taste,Pu-erh tea fermented by Monascus has rich aroma,unique koji ester fragrance,red liquor color and sweet taste.Yeast fermented Pu-erh tea has fermented aroma,red liquor color and sweet taste,The mixed fermented Pu-erh tea has rich aroma,such as stale aroma,herbal aroma,koji ester aroma,etc.red liquor color,sweet and mellow taste,smooth and thick,and the overall sensory quality of Pu-erh tea fermented by Monascus and yeast is the best.2.The results showed that the contents of flavonoids and caffeine in the mixed fermented Pu-erh tea were higher than those in the other groups,the contents of soluble sugar and amino acids in the fermented Pu-erh tea by Monascus were higher than those in the other groups,and the contents of polyphenols and catechins in the fermented Puerh tea by yeast were higher than those in the other groups.Compared with the raw material,the content of soluble sugar in the bulk samples increased except that in yeast fermentation.The content of amino acid decreased except Monascus fermentation.The contents of flavonoids and caffeine increased,while the contents of tea polyphenols and catechins decreased.3.A total of 120 volatile components,including 28 kinds of alcohols,13 kinds of ketones,15 kinds of aldehydes,24 kinds of esters,8 kinds of heterocyclic compounds,12 kinds of terpenes,19 kinds of hydrocarbons and 1 kinds of phenol,were screened for the determination of volatile substances in the fermented Pu-erh tea stage samples with different treatments.4.The analysis of the mixed fermented Pu-erh tea stage samples showed that the key active substances of Pu-erh tea mainly include cedrol,β-ionone,α-ionone,linalool,1,2,3-trimethoxybenzene,1,2,3,4-tetramethoxybenzene,linalyl acetate,etc.These key active substances together form the rich aroma of stale,wood,flowers and fruits of mixed fermented Pu-erh tea.Through the application of Monascus and yeast mixed fermentation of Pu-erh tea research,revealed a single strain fermentation and mixed strain fermentation on the physical and chemical components of Pu-erh tea,sensory quality and aroma components,clear the beneficial bacteria on the Pu-erh tea flavor quality of the role of the beneficial microbial fermentation,rich Pu-erh tea processing theory provides a reference basis,realize the orientation and flavor of Pu-erh tea fermentation,is conducive to promoting the scientific and healthy development of Pu-erh tea.