Effect Of The Water-soluble Matrix Compositions Of Pu-erh.tea On Release Of Key Aroma Compounds

Taste and aroma are the key indicators for consumers to evaluate Pu-erh tea.The taste compounds,namely matrix components,are mainly composed of water-soluble extracts,such as tea polysaccharides,theanins and tea polyphenols.In addition,the compounds of 1-ethyl-2-formaldehyde-1H-pyrrole,6,10-dimethylundeca-5,9-dien-2-one,2,6-di-tert-buty-1-p-cresol,dihydroactinolide,isophytol,isopropyl palmitate,phytol and methoxybenzene compounds have significantly impact on the aroma of Pu-erh tea.In this study,the effects of water-soluble compositions in Pu-erh tea on the release of key aroma compounds were conducted.The contents of main research are as follows:(1)Analysis of main water-soluble matrix components in Pu-erh teaThe main water-soluble components in Pu-erh tea samples were analyzed,showing that the content of tea extraction ranged from 20.85%to 34.41%;the content of tea polysaccharide ranged from 4.91%to 8.57%;the content of tea polyphenols ranged from 6.12%to 11.88%;the content of gallic acid ranged from 2.39 to 9.79 mg/g;the content of catechin ranged from 0.39 to 0.95 mg/g;the content of epigallocatechin gallate ranged from 0.42 to 2.26 mg/g;the content of epicatechin gallate ranged from 0.91 to 3.09 mg/g.the content of theabrownin ranged from 9.16%to 15.78%。(2)Establishment of analytical method of key aroma compounds in Pu-erh teaThe compounds of 1-ethyl-2-formaldehyde-lH-pyrrole,6,10-dimethylundeca-5,9-dien-2-one,2,6-di-tert-butyl-p-cresol,dihydroactinolide,isophytol,isopropyl palmitate and phytol were used as the research objects.The extraction efficiency of four different fibres(65 μm DVB/PDMS,75 μm CAR/PDMS,50/30 μm DVB/CAR/PDMS,85 μm PA)on key aroma compounds were compared,demonstrating that the 50/30 m DVB/CAR/PDMS fibre had the best extraction efficiency on the above compounds,and then the extraction conditions were optimized.The optimum conditions of HS-SPME were as follows:extraction temperature 80℃ extraction time 60 min,equilibrium time 10 min,and resolution time 7 min.(3)Effect of main water-soluble matix components of Pu-erh tea on the release of key aroma compounds.In order to further study the effect of different matrix components on the release of target aroma compounds in Pu-erh tea,the interaction between different water-soluble matrix components and target aroma compounds were analyzed by establishing simulation system.The results showed that the gallic acid and catechins promoted the release of target aroma compounds,while other matrix components inhibited the release of target aroma compounds.