不同氨基酸对普洱熟茶呈味物质和香气成分的影响

Effect of Different Amino Acids on the Flavour and Volatile Aroma Components of Ripe Pu-erh Tea

摘要:

氨基酸是普洱茶发酵过程中重要的中间物质，对普洱茶内含物质的转化和品质都有着重要的影响。本文探讨了在发酵时添加不同氨基酸对普洱熟茶产品的主要呈味物质和挥发性香气成分的影响。结果表明，添加外源氨基酸组的水浸出物含量在34.82~39.46%之间，茶褐素含量在6.31~7.17%之间，游离氨基酸的含量在6.31~7.17%之间，这三项指标均高于对照组；茶多酚含量在7.76~8.73%之间，水溶性糖在3.07~3.89%之间，均低于对照组，咖啡碱含量与对照组相差不大。挥发性香气成分分析表明，醇类占香气成分的21.17~25.47%、醛类占15.64~18.71%、杂氧化合物类占13.75~17.92%、酯类占7.17~10.25%，这几类物质是主要的香气成分；实验组香气成分中的酯类和杂氧化合物类含量大于对照组，而它们又是陈年普洱茶的主要的特征香气成分。实验表明外源氨基酸对普洱茶汤中的呈味物质以及香气成分的形成有显著影响，能加快普洱茶特殊品质的形成。

Abstract:

Amino acids are important intermediate during fermentation process of Pu-erh tea, and have significant influence on the transformation of tea components and its quality. This article explored the effects of different amino acids on the flavour and volatile aroma components of ripe Pu-erh tea fermented upon the addition of amino acids. The results demonstrated that the contents of water extract, theabrownins and free amino acids were at the range of 34.82~39.46%, 6.31~7.17% and 6.31~7.17%, respectively, higher than those of the control group. The tea polyphenols and water-soluble sugars were at the range of 7.76~8.73% and 3.07~3.89% respectively, lower than those of the control group. No significant difference of caffeine content was observed. The analysis of the volatile aroma components showed that alcohols (21.17~25.47% of the total volatile aroma components), aldehydes (15.64~18.71%), heterocyclic oxygen compounds (13.75~17.92%) and esters (7.17~10.25%) were the main aroma components. The contents of esters and heterocyclic oxygen compounds of experimental groups were higher than that of the control one, and this two kinds of components were the characteristic components of aged Pu-erh aroma. These results showed that exogenous amino acids had significant impact on the formation of flavour components in tea soup and volatile aroma components, and could accelerate the special quality formation of Pu-erh tea.