陈香型铁观音陈化过程中特征有机酸变化分析

Variation of Characteristic Organic Acids during Aging Process of Old Tieguanyin Tea

为探究铁观音陈化过程中有机酸组分变化规律,建立陈香型铁观音陈化品质监控体系,采用高效液相色谱(high performance liquid chromatography,HPLC)法测定铁观音当年新茶、存放6、9、13、18、25、30年的陈茶中10种有机酸的含量。计算各年份茶有机酸组分的滋味活力值(taste activity value,TAV),考察各有机酸的酸味贡献。结果表明:铁观音陈化过程中的有机酸总量高于新茶,呈现“先升后降,再逐渐平稳”的趋势,第6年总酸含量最高,是新茶的1.77倍。乳酸(44.6%~54.5%)和琥珀酸(24.8%~37.1%)是陈化过程中的主要有机酸,除乙酸和DL-酒石酸,其余检出酸均呈现陈化前期波动明显,陈化后期变化温和的特点,与铁观音陈化前期酸味刺激强烈而后期滋味醇和的审评特征一致。计算有机酸TAV发现只有琥珀酸TAV在陈化中始终高于1,是陈化过程主要呈酸物质。

To study alterations in organic acid components of Tieguanyin tea during aging process and to establish regulatory systems concerning aging quality of old Tieguanyin tea,concentrations of 10 organic acids in fresh Tieguanyin tea and 6 aged Tieguanyin teas(aged 6,9,13,18,25 and 30 years)were measured using high performance liquid chromatography.The contribution of each organic acid to sour taste was analyzed using taste activity value(TAV).The content of the sum of 10 organic acids tended to initially increase and then decrease and level off during ageing;however,the content of organic acids was higher in all aged Tieguanyin teas than in fresh tea.The highest concentration of organic acids occurred in 6-year-old tea,which was 1.77-fold high than that in fresh tea.Lactic acid and succinic acid were the predominant organic acids,accounting for approximately 44.6%-54.5%and 24.8%-37.1%of the 10 organic acids,respectively.Each organic acid,apart from acetic acid and DL-tartaric acid,showed marked fluctuation during the early period of aging,but changes were moderate during later stage.These characteristics explained why aged Tieguanyin teas had a strong sourtaste during early aging stages and showed a mellow,not astringent flavor at later stages.The variation in TAV of organic acids showed that succinic acid was the predominant contributor to sour taste at TAV>1 throughout the aging process.