基于气相离子迁移谱和电子鼻技术分析核桃挥发性风味物质

Analysis of volatile flavor compounds in walnut by gas chromatography-ion mobility spectrometry and electronic nose

为研究不同品种核桃挥发性风味物质的差异和核桃品种的区分方法,以5种核桃为研究对象,采用气相离子迁移谱(GC-IMS)和电子鼻(E-nose)技术结合主成分分析(PCA)、线性判别分析(LDA)和聚类分析,对核桃挥发性风味物质的组成及品种差异进行了研究。结果表明:GC-IMS技术结合聚类分析和E-nose技术结合LDA分析均能有效区分核桃品种;采用GC-IMS技术从5种核桃中分离出73种挥发性成分,鉴定出其中19种物质,主要有醇类、酮类、醛类和酯类,其中乙醇、2-甲基丙醇、1-戊醇、3-甲基-3-丁烯-1-醇、正己醇、2-庚酮、戊醛、己醛、庚醛、壬醛、苯甲醛和乙酸乙酯是区分核桃品种的关键物质;E-nose分析结果表明,W3C、W5C、W1C和W6S传感器在区分核桃品种上有较大贡献,LDA由于考虑了组间差距,对于核桃品种的区分相较PCA更为明显;两种风味分析技术相比较,GC-IMS可对挥发性物质进行定性和定量检测,E-nose虽不能鉴定挥发性物质的具体种类,但样品处理简单,可实现品种的快速区分。

To study the differences of volatile flavor compounds in different walnut varieties and the distinguishing methods of walnut varieties, five walnut varieties were selected as study subjects, and gas chromatography-ion mobility spectrometry(GC-IMS) and electronic nose(E-nose) technology with the combination of PCA, LDA and cluster analysis were used to study the composition of volatile flavor compounds and variety differences of walnuts. The results showed that GC-IMS combined with cluster analysis and E-nose technology combined with LDA could effectively distinguish walnut varieties. In addition, a total of 73 volatile compounds were separated by GC-IMS from the five walnut varieties, and 19 substances were identified, mainly including alcohols, ketones, aldehydes and esters. Moreover, key substances to distinguish walnut varieties were determined as follows: ethanol, 2-methyl-1-propanol, 1-pentanol, 3-methyl-3-butene-1-ol, n-hexyl alcohol, 2-heptanone, pentanal, hexanal, heptanal, nonanal, benzaldehyde and ethyl acetate. The results of E-nose analysis showed that W3 C, W5 C, W1 C and W6 S sensors had a greater contribution to the differentiation of walnut varieties, and LDA was more obvious than PCA in the differentiation of walnut varieties due to the consideration of inter-group differences. Compared with the two flavor analysis techniques, GC-IMS could conduct qualitative and quantitative detection of volatile substances. E-nose couldn’t identify the specific types of volatile substances, but the sample processing was simple and could realize the rapid differentiation of varieties.