Effects Of Grades And Storage Durations On The Quality And Bioactivities Of Pu-erh Tea

Geographical indication products pu-erh tea in Yunnan province which uses theYunnan big leaf dried green tea within the scope of protection of geographicalindications as raw material, and in the specific environment conditions within the scopeof the geographical indication protection, through some special processing technologies,and has unique quality characteristics of post-fermentation tea. because pu-erh tea has aseries of medical and health function about reducing hematic fat, lowering blood pressure,resisting arteriosclerosis, anti-oxidation, anti-aging and so on, it is popular withconsumers in domestic or overseas, pu-erh tea hot was started successively in HongKong, Macao, Taiwan, Southeast Asia, and South Korea, Japan, France, Germany andother places.In our study, we used9kinds of pu-erh tea with different materials levels or differentstorage durations, and do some analysis and comparisons about their chemicalcomposition change, color and luster change, and sensory quality review, than weresearched their biological activities. The purpose of this study is to provide some basistheories for evaluating pu-erh tea materials levels and storage times, and developing itshealth efficacy.Combining the measurement of the main chemical compositions with sensoryevaluation, results showed as follows: when the level of raw materials was increased,some changes could be found. The total free amino acid content increased significantly;amino acid components, EGCG content, Ca ion concentration were increased; Mg、Na、Zn and other ions were decreased; and the sensory evaluation score was promoted byappearance and quality improving. By the way, when storage durations was extended,total free amino acid, catechin, tea polyphenol content were reduced, gallic acid co ntentwas increased, caffeine got a wavy change, Mg、Na、Zn and other ions concentrationwere decreased, and pleasant aroma was scented and quality was improved.Using chromatic meter to measure pu-erh tea colour, rearch results showed that: whenthe level of raw materials was decreased, the dry tea brightness (L value) and yellow (bvalue) were increased, brightness of tea liquor and infused leaf reduced gradually, andred (a value) was also decreased. On the other hand, when storage times was extended,the brightness of tea liquor and infused leaf increased obviously, a value and b value of tea liquor had a gradual decline. Chroma value and the results of sensory evaluation weresimilar with each other.The promotion and inhibition effects of pu-erh tea water extract were also be studied.Results showed that the pu-erh tea water extract showed an effective inhibitory effect onE.coli and S.aureus, and a marked positive effect on Lb. Through correlation analysisfound that there was a highly negative correlation between pu-erh tea polyphenol andcatechins contents of different levels of raw materials or storage durations and waterextract on the inhibition of E.coli. Meanwhile, positive correlations appeared betweenpu-erh tea polyphenol and catechins contents and water extract on the inhibition ofS.areus and the growth promotion of Lb.