基于气味活度值法的凌云白毫发酵茶香气特征分析

Analysis of Aroma Characteristics of Fermented Lingyun Baihao Tea Based on Odor Activity Value

为分析不同类型凌云白毫发酵茶的香气成分差异及呈香特点,采用固相微萃取-气相色谱-质谱联用技术鉴定茶叶香气成分,运用气味活度值(odor activity value,OAV)法确定关键风味组分,结合主成分分析(principal component analysis,PCA)、正交偏最小二乘判别分析(orthogonal partial least squares-discrimination analysis,OPLS-DA)、聚类分析和感官审评对凌云白毫发酵茶香气进行综合评价。结果表明,共鉴定出48种香气成分,其中15种关键和修饰性风味组分(OAV>0.1),PCA模型(R_(X)^(2)(cum)=0.984,Q^(2)(cum)=0.846)和OPLS-DA(R_(X)^(2)(cum)>0.7,Q^(2)(cum)>0.9)模型拟合度高,主要差异成分为芳樟醇、异戊醇、2-甲基丁醛、β-紫罗兰酮、壬醛和茉莉酮。聚类分析将15种香气成分分为3类,Ⅰ类包含吲哚、脱氢芳樟醇,Ⅱ类包含芳樟醇、壬醛、苯乙醛、己醛、2-甲基丁醛、异戊醛、苯乙醇和异丁醛,Ⅲ类包含茉莉酮、β-紫罗兰酮、水杨酸甲酯、2-正戊基呋喃和二甲基硫,乌龙茶组表现突出的香气组分为Ⅰ类,红茶组为Ⅱ类,白茶组为Ⅲ类,黄茶组为Ⅱ、Ⅲ类,分析所得各茶类的香气特点与感官审评的香气评价相符。OAV法处理气相色谱-质谱数据,再结合PCA、OPLS-DA和聚类分析,可以实现不同工艺发酵茶的区分和评价,研究结果可为凌云白毫多茶类的深入开发提供一定参考依据。

This study aimed to analyze the difference in aroma components and aroma characteristics of different types(white,oolong,yellow and black)of fermented Lingyun Baihao tea.The aroma components were identified by solid phase microextraction(SPME)combined with gas chromatography-mass spectrometry(GC-MS),and odor activity value(OAV)was used to determine the key flavor components.By combined use of principal component analysis(PCA),orthogonal partial least square-discriminant analysis(OPLS-DA),cluster analysis and sensory evaluation,the aroma of fermented Lingyun baihao tea was comprehensively evaluated.The results showed that a total of 48 aroma compounds were identified in the tea samples,including 15 key flavor components and flavor-modifying components(OAV>0.1).The cumulative interpretation rate R_(X)^(2)(cum)and the cumulative prediction rate Q^(2)(cum)of the PCA model were 0.984 and 0.846,respectively,and those of the OPLS-DA model were greater than 0.7 and 0.9,respectively.Both models had good fitness.The major differential components were linalool,isoamyl alcohol,2-methylbutyraldehyde,β-ionone,nonanal and jasmone.The 15 aroma components were classified into three categories by hierarchical cluster analysis(HCA).Class Ⅰ contained indole and dehydroalinalool,Class Ⅱ contained linalool,nonanal,phenylacetaldehyde,hexanal,2-methylbutyraldehyde,isovaleraldehyde,phenylethanol and isobutyraldehyde,and Class Ⅲ contained jasmone,β-ionone,methyl salicylate,2-pentylfuran and dimethyl sulfide.Class Ⅰ was prominent in oolong tea samples,Class Ⅱ was prominent in black tea samples,Class Ⅲ was prominent in white tea samples,and Class Ⅱ and Ⅲ were prominent in yellow tea samples.These aroma characteristics were consistent with the results of sensory aroma evaluation.GC-MS analysis and OAV calculation combined with PCA,OPLS-DA and HCA can enable the identification and evaluation of Lingyun Baihao fermented tea aroma.The results of this study can provide a reference for the further development of Lingyun Baihao tea.