厌氧发酵时间对黄金芽绿茶γ-氨基丁酸含量及品质成分的影响

Effects of anaerobic fermentation time onγ-aminobutyric acid content and quality components of Huangjinya green tea

【目的】研究不同厌氧发酵时间处理对黄金芽绿茶γ-氨基丁酸(GABA)含量及品质成分的影响,明确高品质高GABA含量黄金芽绿茶的最佳厌氧时间,为黄金芽绿茶的产品研发及茶叶品质提升提供理论依据。【方法】以黄金芽1芽2、3叶为原料,常规摊放后,采用食品真空封口机抽真空封口包装,进行0(对照)、3、6、9、12和15 h室内常温厌氧,采用绿茶工艺制样。采用高效液相色谱仪检测茶样GABA含量,结合感官审评和品质成分检测,分析厌氧发酵时间对黄金芽绿茶GABA含量及品质成分影响的变化规律。【结果】厌氧后,制得的黄金芽绿茶GABA含量均达GABA茶标准(1.50 mg/g),其中,厌氧6 h的GABA含量最高(2.50 mg/g),是对照(0.20 mg/g)的12.5倍。厌氧6 h内,茶样感官品质正常,外形条索完整、金黄,汤色绿黄明亮,香气纯正,滋味鲜醇,叶底金黄明亮,厌氧超6 h后,感官品质下降明显,表现为外形条索完整、金黄,汤色黄、较亮,香气熟闷,滋味青涩,叶底色杂、带红梗。厌氧后,游离氨基酸含量增幅为0~9.43%,咖啡碱和水浸出物含量降幅分别为1.89%~14.83%和2.26%~6.41%,茶多酚和总黄酮含量无显著变化(P>0.05,下同),酚氨比变幅为0.16%~4.06%;儿茶素总量增幅为1.91%~7.93%,儿茶素苦涩味指数无显著变化;类黄酮总量增幅为132.15%~169.06%;氨基酸总量降幅为10.03%~27.64%。对照茶样中,以茶氨酸(The)和苯丙氨酸(Phe)含量最高,分别为1.23和0.96 mg/g;其次为天冬氨酸(Asp)和谷氨酸(Glu),含量分别为0.84和0.81 mg/g;半胱氨酸(Cys)含量最低,仅为0.04 mg/g。厌氧茶样中,以GABA和The含量最高,分别为1.60~2.50 mg/g和1.12~2.30 mg/g;其次为赖氨酸(Lys),含量为0.72~0.82 mg/g;以谷氨酰胺(Gln)、缬氨酸(Val)、Cys、异亮氨酸(Ile)和亮氨酸(Leu)含量较低,为0.02~0.05 mg/g。随着厌氧发酵时间的延长,茶样的鲜味类氨基酸含量升高,增幅为10.59%~45.29%,而芳香类、苦味类、甜味类和酸味类含量降低,降幅分别为28.79%~50.00%、51.85%~85.80%、68.72%~78.97%和82.24%~96.26%。【结论】厌氧6 h处理的茶样GABA含量最高,且综合品质佳,可作为加工黄金芽GABA绿茶的最佳厌氧发酵时间。

【Objective】To study the effects of different anaerobic fermentation time treatments on Huangjinya green teaγ-aminobutyric acid(GABA)content and quality components,the optimal anaerobic time for high quality and high GABA content Huangjinya green tea was clarified,which provided a theoretical basis for the product development of Huangjinya green tea and tea quality improvement.【Method】Used one bud,two leaves and three leaves of Huangjinya as raw materials,after conventional spreading,vacuum sealing packaging was carried out using a food vacuum sealing machine.The samples were anaerobic at room temperature for 0(control),3,6,9,12,and 15 h,and prepared using green tea technology.High performance liquid chromatograph was used to detect the GABA content in tea samples,combined with sensory evaluation and quality component detection,to analyze the changes in the influence of anaerobic fermenta-tion time on the GABA content and quality components of Huangjinya green tea.【Result】After anaerobic treatment,the GABA content of the tea samples reached the GABA tea standard(1.50 mg/g),with the highest GABA content(2.50 mg/g)after 6 h of anaerobic treatment,which was as 12.5 times as the control sample(0.20 mg/g).Within 6 h of anaerobic treatment,the sensory quality of the tea sample was normal,with a complete and golden appearance,a bright green and yellow soup color,a pure aroma,a fresh and mellow taste,and a golden and bright leaf base.After more than 6 h of anaero-bic treatment,the sensory quality decreased obviously,manifested as a complete and golden appearance,a bright yellow soup color,a ripe and stuffy aroma,a green and astringent taste,mixed leaf base color,and a red stem.After anaerobic treatment,the increase in amino acids was 0-9.43%,the decrease rates of caffeine and water extracts contents were 1.89%-14.83%and 2.26%-6.41%,respectively,there was no significant change in the contents of tea polyphenols and total flavonoids(P>0.05,the same below),with a polyphenols/amino acid ratio ranging from 0.16%to 4.06%,the total amount of catechin increased by 1.91%-7.93%,and the bitterness and astringency index of catechin did not change signifi-cantly,the total flavonoid glycosides increased by 132.15%-169.06%,the total amount of free amino acids decreased by 10.03%-27.64%.Among the control samples,the theanine(The)and phenylalanine(Phe)contents were the highest with 1.23 and 0.96 mg/g respectively,followed by aspartate(Asp)and glutamate(Glu)with 0.84 and 0.81 mg/g.Cysteine(Cys)content was the lowest(0.04 mg/g).Among anaerobic samples,GABA and The had the highest content,ranging from 1.60-2.50 mg/g and 1.12-2.30 mg/g respectively,followed by lysine(Lys),ranging from 0.72-0.82 mg/g.Glutamine(Gln),valine(Val),Cys,isoleucine(Ile)and leucine(Leu)had the low contents,ranging from 0.02 to 0.05 mg/g.while the content of fresh amino acids increased by 10.59%-45.29%,while the contents of aromatic,bitter flavour,sweet fla-vour,and sour flavour amino acids decreased by 28.79%-50.00%,51.85%-85.80%,68.72%-78.97%and 82.24%-96.26%,respectively.【Conclusion】The tea samples treated with anaerobic fermentation for 6 h have the highest GABA content and excellent overall quality.It can be used as the optimal anaerobic fermentation time for processing Huangjinya GABA green tea.