Analysis of Changes in Aroma Components of Pu-erh Tea during Post-fermentation Process

Abstract

Objective;To reveal the origin of aroma substances in ripe Pu-erh tea and provide guidance for the production of ripe Pu-erh tea by exploring the changes in aroma components during post-fermentation process. Methods;Simultaneous distillation-solvent extraction was applied to extract aroma compounds from Pu-erh tea samples at different post-fermentation stages, and the aroma compounds were analyzed by GC-MS. Besides, these Pu-erh tea samples were subjected to sensory evaluation. Results;65 kinds of aroma components were totally identified in Pu-erh tea samples at different post-fermentation stages, including 11 hydrocarbon kinds, 10 alcohol kinds, 13 aldehyde kinds, 10 ketone kinds, 6 acid kinds, 6 ester kinds, and 9 other compound kinds. The main aroma components of sunshine withering tea were linalool, 4-phenyl-pyridine, phytol, 3,7 dimethyl-1,6- octadiene-3-alcohol, n-palmitic acid, and 4-methyl-2-propyl-1-pentanol, and those of ripe Pu-erh tea were n- palmitic acid, dihydro-kiwi lactone, dihydro lactone anemones, diethyl-2-13 methyl alcohol, and trans-keto- β -malaysia. The relative contents of ketones, aldehydes, acids, and esters increased, but those of alcohols and other compounds decreased over the post-fermentation process. Both type and quantity of methylated substances presented rising trend with the post-fermen- tation extending. The sensory evaluation indicated that the change from clean aroma to stale flavor occurred in the process from sunshine withering tea to ripe Pu-erh tea.