基于SPME-GC-MS和电子鼻分析方法分析薏仁饮料贮藏过程风味化合物变化

Change of Flavor Compounds in Coix Seed Beverage during Storage Analyzed by SPME-GC-MS and Electronic Nose

采用固相微萃取-气相色谱-质谱和电子鼻分析技术,通过相对气味活度值(relative odor activity value,ROAV)、主成分分析和聚类分析方法,对薏仁饮料保温贮藏过程中风味化合物、风味变化特征进行研究。结果表明:37℃贮藏35 d,样品共检测出39种主要的挥发性化合物,醛、醇、酮、烃、酯类化合物相对含量随贮藏时间延长而增加;贮藏期间ROAV不小于1的关键风味化合物有9种,按贡献度大小依次为1-辛烯-3-醇、壬醛、3-甲基丁醛、己醛、辛醛、2-甲基丁醛、1-戊醇、辛醇、1-己醇;薏仁油脂氧化产生的醛、酮、酸和醇等挥发性化合物是薏仁饮料风味的主要成分;采用主成分分析及聚类分析能有效区分不同贮藏时间薏仁饮料,主成分分析显示样品贮藏初期和贮藏中后期的数据无重叠,其挥发性化合物存在差异,聚类分析结果将不同贮藏时间样品分为6类,区分效果较好;通过主成分分析、ROAV和挥发性化合物相对含量变化,由此判定薏仁饮料贮藏期间品质劣变的特征性化合物为壬醛、己醛、辛醛、1-辛烯-3-醇。

The change of flavor compounds in coix seed beverage during constant-temperature storage was investigated using solid phase microextraction-gas chromatography-mass spectrometry（SPME-GC-MS） and an electronic nose system. The key flavor compounds were identified by their relative odor activity value（ROAV）. Principal component analysis（PCA） and cluster analysis（CA） were applied to discriminate between samples stored for different periods. The results showed that after storage at 37 ℃ for 35 d, a total of 39 major volatile compounds were detected in coix seed beverage. The relative contents of aldehydes, alcohols, ketones, hydrocarbons and esters were increased with storage time. 1-Octen-3-ol, nonanal, 3-methylbutanal, hexanal, octanal, 2-methylbutanal, 1-pentanol, octanol and 1-hexanol, with ROAV no less than 1, were the key odor compounds of coix seed beverage during storage. The volatile compounds of aldehydes, ketones, acids and alcohols, produced from the oxidation of coix seed oil, were the main flavor components of coix seed beverage. PCA and CA could clearly distinguish between coix seed beverages with different storage times, and the PCA plot showed no overlapping between the early and mid-late stages of storage and differences in volatile compounds. By CA analysis, the samples with different storage times were discriminated effectively and classified into six clusters. Based on PCA analysis, ROAV and the changes in the relative contents of volatile compounds, nonylaldehyde, hexanal, octanal, 1-octen-3-ol were the characteristic volatile compounds causing quality deterioration of coix seed beverage during storage.