保康不同等级绿茶主要化学成分的比较分析

Comparative Analysis on Main Chemical Components of Different Grades of Green Tea from Baokang

为了解保康不同等级绿茶的品质特征及其差异,收集保康绿茶一级茶样4个、二级茶样4个,联合采用感官审评法、高效液相色谱法、气质色谱联用法和主成分分析法系统测定分析了其香气成分、滋味成分的组成和含量。结果显示:一级绿茶的感官总分均高于90分,二级绿茶低于90分,感官品质得分与市场所定等级一致;一级绿茶的水浸出物、茶多酚、氨基酸、咖啡碱、酯型儿茶素和儿茶素总量均值均高于二级绿茶,只有非酯型儿茶素总量略低于二级绿茶;不同等级绿茶中咖啡碱、没食子酸、酯型儿茶素和儿茶素总含量均值有显著差异,水浸出物、茶多酚、氨基酸和非酯型儿茶素含量均值无显著差异;8个茶样共检测到64种香气化合物,包括醇类13种、醛类9种、酮类5种、烯类12种、芳香烃6种、酯类15种和其他类4种,其中醇类物质平均含量最高,酯类其次,含量较高的成分有芳樟醇、香叶醇和己酸顺式-3-己烯酯;进一步主成分分析发现,4个主成分方差累计贡献率达到89.608%,其中第1主成分方差贡献率为45.080%,综合了β-紫罗酮、邻二甲苯、乙苯、苯乙烯、二甲基戊酸甲酯和顺-茉莉酮的贡献,主要反映绿茶中的花果香及特有芳香;一级绿茶醇类和酯类香气化合物的平均含量低于二级绿茶,醛类、酮类、烯类、芳烃类和其他类香气化合物含量均高于二级绿茶。

In order to understand the quality characteristics and differences of different grades of Baokang green tea,four first grade of tea samples and four second grade of tea samples of Baokang green tea were collected.Sensory evaluation,High-performance liquid chromatography(HPLC),Gas chromatography–mass spectrometry(GC-MS)and Principal component analysis(PCA)were used to determine and analyze the composition and contents of aroma components and taste components.The results showed that the total sensory score of the first grade green tea was higher than 90,while that of the second grade green tea was lower than 90,the score of sensory quality was consistent with the market level;the mean values of water extract,tea polyphenols,amino acids,caffeine,ester catechins and total catechins of the first grade green tea were higher than those of the second grade green tea,only the total contents of non ester catechins were slightly lower than those of the second grade green tea;the contents of caffeine,gallic acid,ester catechins and total catechins in different grades of green tea were significantly different,but the contents of water extract,tea polyphenols,amino acids and non ester catechins had no significant difference;A total of 64 aroma compounds were detected in 8 tea samples,including 13 alcohols,9 aldehydes,5 ketones,12 alkenes,6 aromatic hydrocarbons,15 esters and 4 other aromatic compounds,among which the average content of alcohol was the highest,followed by esters,and the higher contents were linalool,geraniol and cis-3-hexenyl hexanoate;Further principal component analysis found that the cumulative contribution rate of variance of the four principal components reached 89.608%,and the variance contribution rate of the first principal component was 45.080%,which integrated the contribution of β-ionone,o-xylene,ethylbenzene,styrene,methyl dimethylvalerate and CIS Jasmine ketone,mainly reflected the flower and fruit fragrance and special fragrance in green tea;The average contents of alcohol and ester aroma compounds in the first grade green tea was lower than those in the second grade green tea,and the contents of aldehydes,ketones,alkenes,aromatics and other aroma compounds were higher than those in the second grade green tea.It provides theoretical support for improving the quality and build a brand of green tea from Baokang.