基于HS-SPME-GC-MS探究压制及陈化对南川大树茶毛茶及其沱茶香气的影响

Exploring the Effects of Compressing and Aging on the Aroma of Camellia nanchuanica Crude Tea and Its Tuo Tea Based on HS-SPME-GC-MS

为探究南川大树茶毛茶压制前后香气成分的变化及陈化对其沱茶香气的影响,本文采用传统感官评审结合顶空固相微萃取-气相色谱-质谱联用仪(Headspace-solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS)对茶样香气进行分析,通过正交偏最小二乘法判别分析(Orthogonal partial least squares discriminationanalysis, OPLS-DA)建立判别模型,并基于变量投影重要性分析(Variableimportancein projection,VIP值)结合香气活度值(Odor activity value,OAV)筛选不同茶样中的特征香气。结果表明:南川大树茶毛茶压制前后与沱茶陈化处理后其香气评分存在显著差异(P<0.05)。通过HS-SPME-GC-MS从6个茶样中共鉴定出114种香气成分,与毛茶相比,压制后沱茶的香气种类及含量均明显降低,1-辛烯-3-醇等低沸点香气化合物损失较大;通过陈化处理的沱茶香气种类更为丰富,其中1,2-二甲氧基苯为陈化处理后沱茶样品中的特有物质。基于107种共有香气成分建立的OPLS-DA可实现对不同茶样的有效区分,以VIP值>1与OAV>1为标准共筛选出23种特征香气成分,苯乙醇、(E)-2-庚烯醛等17种香气成分为大树茶毛茶样品中重要的香气成分,反式-2-壬醛、反-2-辛烯醛等6种香气成分为大树茶沱茶样品中的重要香气成分。本研究为大树茶沱茶的加工贮藏提供参考。

To investigate the changes in aroma components of Camellia nanchuanica crude tea before and after compression and the effects of aging on the aroma of Tuo tea,traditional sensory evaluation combined with headspace solid-phase microextraction-gas chromatography-mass spectrometry(HS-SPME-GC-MS)was employed for aroma analysis of tea samples in this study.A discriminant model was established through orthogonal partial least squares discrimination analysis(OPLS-DA),and characteristic aromas in different tea samples were screened based on variable importance in projection(VIP values)and odor activity values(OAV).Results showed that there were obvious differences in the aroma score of Camellia nanchuanica tea before and after compressing and aging at room temperature(P<0.05).A total of 114 aroma components were identified by HS-SPME-GC-MS,and compared with crude tea,the aroma types and contents of Tuo tea were significantly reduced after the compressing process,the loss of low-boiling-point aroma compounds,such as 1-octen-3-one was significant while the aroma profile of Tuo tea exhibited increased diversity after undergoing the aging process,with the presence of 1,2-dimethoxybenzene being a distinct characteristic in the aged Tuo tea samples.OPLS-DA based on 107 common aroma components could effectively distinguish different tea samples,based on the double criteria of VIP>1 and OAV>1,a total of 23 characteristic aroma components were screened,seventeen aroma components,including phenethyl alcohol and(E)-2-heptenal were identified as important contributors to the aroma of Camellia nanchuanica crude tea samples,while six aroma components including(E)-2-nonenal and(E)-2-octenal were identified as significant contributors to the aroma of Camellia nanchuanica Tuo tea samples.This study would provide a reference for the processing and storage of Camellia nanchuanica Tuo tea.