不同杀青方式对黄金芽绿茶γ-氨基丁酸含量及品质成分的影响

Effects of different fixation methods on γ-aminobutyric acid content and quality components of Huangjinya green tea

  • 摘要: 【目的】研究不同杀青方式对真空厌氧处理黄金芽绿茶γ-氨基丁酸(GABA)含量和主要品质成分的影响,筛选出能有效保留GABA和提高茶叶品质的最佳杀青方式,为高含量GABA黄金芽绿茶生产及黄金芽精深加工提供理论依据。【方法】通过微波、滚筒、蒸汽和锅炒4种杀青方式对常温下真空厌氧处理6 h后的茶样进行杀青处理,运用高效液相色谱法(HPLC)检测茶叶GABA含量,并根据国家标准方法测定水浸出物(AE)、游离氨基酸、咖啡碱(CAF)、茶多酚、儿茶素组分和类黄酮等主要品质成分含量,同时利用主成分分析(PCA)和正交偏最小二乘判别分析(OPLS-DA)方法对黄金芽绿茶特征性成分进行分析。【结果】微波杀青对黄金芽绿茶GABA含量保留效果最好,为1.66mg/g,达GABA茶的标准(≥1.50mg/g);其游离氨基酸总量(3.88%)、简单儿茶素总量(50.92mg/g)、表没食子儿茶素(EGC)含量(41.47 mg/g)、表没食子儿茶素没食子酸酯(EGCG)含量(64.48 mg/g)、表儿茶素没食子酸酯(ECG)含量(2.45 mg/g)、儿茶素没食子酸酯(CG)含量(13.70 mg/g)、儿茶素总量(134.20 mg/g)和类黄酮总量(11.54 mg/g)均显著高于其他3种杀青方式加工的绿茶(P<0.05);茶多酚含量和酚氨比均低于其他茶样,分别为16.03%和4.13;CAF含量为40.07 mg/g,较蒸汽杀青茶样低,但在绿茶中已达较高水平。PCA结果显示微波杀青加工的茶样主要品质成分明显区别于其他杀青方式,且儿茶素(C)、杨梅素(Myr)、GABA、没食子酸(GA)、CAF、AE和表儿茶素(EC)是引起微波杀青、滚筒杀青、蒸汽杀青和锅炒杀青茶样品质成分存在差异的主要标志性成分。【结论】微波杀青方式加工的黄金芽绿茶GABA含量保留量最高,品质成分损耗最小,总体品质优异,可作为加工黄金芽GABA绿茶的最佳杀青方式。

     

    Abstract: 【Objective】By studying the effects of different fixation methods on the γ-aminobutyric acid(GABA) content and main quality components in Huangjinya green tea treated by vacuum anaerobic treatment,the best way of fixation that could effectively retain GABA and improve tea quality was screened, which could provide theoretical basis for the production of high content GABA Huangjinya green tea and the deep processing of Huangjinya. 【Method】In this experiment,the tea samples treated with vacuum anaerobic treatment at room temperature for 6 h by four different fixation methods,namely microwave,roller,steam and pan frying. The GABA content of the tea was determined by high-performance liquid chromatography(HPLC). And according to the national standard method, the main quality components such as aqueous extract(AE), total free amino acids, caffeine(CAF), tea polyphenols, catechin components and flavonoids were determined, simultaneously using principal component analysis(PCA) and orthogonal partial least squares discriminant analysis(OPLS-DA) to analyze the characteristic components of Huangjinya green tea. 【Result】The microwave sterilization had the best retention effect on GABA content in Huangjinya green tea,at 1.66 mg/g,meeting the standard of GABA tea(≥1.50 mg/g). The total free amino acids content(3.88%),simple catechins content(50.92 mg/g), epigallocatechin(EGC) content(41.47 mg/g), epigallocatechin gallate(EGCG) content(64.48 mg/g), epigallocatechin gallate(ECG) content(2.45 mg/g), catechin gallate(CG) content(13.70 mg/g), total catechins content(134.20 mg/g) and total flavonoid content(11.54 mg/g) were significantly higher than those of the green tea processed by the other three fixation methods(P<0.05); the polyphenol content and phenol to ammonia ratio were significantly lower than those of the other tea samples,they were 16.03% and 4.13 respectively. The CAF content was 40.07 mg/g,which was lower than that of steam fixation tea samples,but it was already at a higher level in green tea. The PCA results show that the main quality components of tea samples processed by microwave fixation were significantly different from other fixation methods,and catechin(C),myricetin(Myr),GABA,gallic acid(GA),CAF,AE and epicatechin(EC) were the main marker components that caused the difference in the quality components of microwave fixation,drum fixation,steam fixation and pot fried fixation. 【Conclusion】The microwave fixation has the highest retention of GABA content and the lowest loss of quality components in Huangjinya green tea among the four fixation methods, the overall tea quality is excellent. So microwave fixation can be used as the best way to process Huangjinya GABA green tea.

     

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