The Study Of Aroma Components, Tea Polysaccharides And Pectins During Fermentation Process Of Pu-erh Tea

Pu-erh tea is one of the important tea cartivars in China, and its conmercial marketcovers the southern China and Southeast Asia. Pile-Fermentative process is a critical stageto form Pu-erh tea special quality, and during this process, the internal materials in Pu-erhtea sample were significantly changed by the effect of wet, heat and enzymes, possibly toproduce new components. Thus it takes an important role to affect the quality of tea. Basedon this, this article aimed to investigate the change of content and species of relatedsubstances in the pile-fermentative process of Pu-erh tea, and necessary discussion wasalso taken. The main results were as follows:1) Identification of the volatile component. Because the species and quantity of thevolatile component were correlated with flavor and aroma of Pu-erh tea, the volatilecomponent was identified by GC–MS in this article, including free and acid-hydrolysisvolatiles. It was found that alcohols, methoxy compounds, acids, esters are major species,and content or abundance of those species are different from each other duringpile-fermentation process.2) The change of the free aroma components. The content of free aroma componentswas correlated with the soup aroma and flavor of Pu-erh tea. The research had found thathigh-volatile component, mainly inherent alcohols, was decreased with the prolonging ofpile-fermentation time, and that low-volatile component, mainly methoxy compounds, wasincreased with the prolonging of the time.3) The change of the acid-hydrolyzed aroma components. Aroma components of thecorresponding acid-hydrolyzed volatile may be combined with matrix compounds bychemical bond. It could be released at certain condition, and had the potential to contributearoma to teas. The component for the acid-hydrolyzed in Pu-erh tea were alcohols, acidsand esters, of which the total amount was less than those of the free, and the content tend todegrease with prolonging of the pile-fermentative process.4) The change of glycoside. The glycosides will be hydrolyzed by enzymes, releasingthe corresponding volatile aglycones to tea matrices and providing aroma flavor for tea.The level of glycosides contents in Pu-erh tea was a reference index for aroma-releasingpotential based on the glycoside. During the fermentative process, the total amount ofglycosides was decreased with the time, and the amount of diglycosides is much largerthan those of monoglucosides.5) Investigation of tea polysaccharide and pectin. Tea polysaccharides and water-soluble pectin has a significant effect on Pu-erh tea taste of the soup. The originalpectin could transform to water-soluble pectin after fermentation. The content of teapolysaccharide and water-soluble pectin gradually increased with the extension offermentative process, but after4th turned-pile, water-soluble pectin decreased, however thetotal amount of tea polysaccharides and water-soluble pectin closed to the maximum valueuntil to the rised-pile. During the fermentative process, the change regularity of the originalpectin was hard to follow, which tended to be decomposed at early stage, while to beaggregated at the late stage.