GC-IMS结合PCA法分析不同焙炒程度留胚米挥发性化合物指纹差异

采用气相色谱-离子迁移谱（gas chromatography-ion mobility spectrometry,GC-IMS）结合主成分分析（principal component analysis,PCA）的方法，分析不同焙炒程度留胚米挥发性风味物质，旨在比较不同焙炒程度留胚米挥发性风味物质的差异，建立不同焙炒程度留胚米挥发性成分指纹图谱。结果显示：不同焙炒程度留胚米样品的挥发性物质可通过GC-IMS技术实现较好分离，在留胚米所有焙炒阶段的4个样品中共检测出61种风味化合物。醛类物质、酯类物质和杂环类化合物对焙炒留胚米的特征性风味贡献较大，醇类和酮类化合物对焙炒留胚米的特征性香气成分也有一定贡献。不同焙炒程度的留胚米香气种类与含量都具有明显差异。PCA表明，留胚米不同焙炒程度挥发性风味成分GC-IMS呈现出一定差异，两个PC累计贡献率达到94%，说明基于GC-IMS技术可以成功建立不同焙炒程度留胚米样品的风味指纹图谱。

Differential Fingerprint Analysis of Volatile Compounds in Rice with Remained Germ Roasted to Different Degrees by Gas Chromatography-Ion Mobility Spectrometry and Principal Component Analysis

The volatile flavor substances of rice with remained germ roasted to different degrees were analyzed and compared by gas chromatography-ion mobility spectrometry (GC-IMS) combined with principal component analysis (PCA), with the aim of establishing fingerprints of volatile components of rice with different roasting degrees. The results showed that the volatile substances of rice samples with different roasting levels could be well separated by GC-IMS, and in total 61 flavor compounds were detected in four rice samples at all roasting stages. Aldehydes, esters and heterocyclic compounds contributed more to the characteristic flavor of roasted rice, while alcohols and ketones also contributed to the characteristic aroma components of roasted rice. The types and contents of aroma compounds of rice with different roasting degrees were significantly different. PCA showed that the GC-IMS spectra of volatile components differed among rice with different roasting degrees, and the cumulative contribution rates of the first two principal components were both 94%, indicating that the flavor fingerprints of rice samples at different roasting levels can be successfully established using GC-IMS.