基于SPME-GC-MS和电子鼻分析薏苡仁油加速氧化过程挥发性成分变化

采用固相微萃取-气相色谱-质谱联用和电子鼻技术分析薏苡仁油氧化期间风味化合物动态变化。结果表明：薏苡仁油加速氧化期间特征挥发性风味物质主要为醛类、酮类、醇类化合物。新鲜油中相对气味活度值大于1的关键挥发性成分贡献度从大到小依次为(E)-2-壬稀醛、(E,E)-2,4-癸二烯醛、(E)-2-癸烯醛、(E,Z)-2,6-壬二烯醛、1-辛烯-3-酮、癸醛，赋予青草气味、油脂味、西瓜样品味；随着氧化时间的延长油脂品质劣变，60 ℃加速氧化30 d时醛类化合物相对含量为73.815%，与新鲜油相比，小分子醛、酸及醇类化合物相对含量增加；薏苡仁油加速氧化后关键风味化合物新增壬醛、辛醛、己醛、(E)-2-辛烯醛，赋予其酸败气味；电子鼻线性判别分析明显区分新鲜油与氧化油以及氧化初期及后期风味物质差异。结果表明(E)-2-壬稀醛、(E,E)-2,4-癸二烯醛等为新鲜薏苡仁油的特征化合物，壬醛、辛醛、己醛等小分子化合物为薏苡仁油加速氧化后的特征化合物。

Changes in Volatile Components of Coix Seed Oil during Accelerated Oxidation Analyzed by Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry and Electronic Nose

The dynamic changes of flavor compounds during the oxidation of coix seed oil were analyzed by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) and an electronic nose. The results showed that the characteristic volatile flavor compounds detected during the accelerated oxidation of coix seed oil were mainly aldehydes, ketones and alcohols. (E)-2-Nonenal, (E,E)-2,4-decadienal, (E)-2-decenal, (E,Z)-2,6-nonadienal, 1-octen-3-one, and decanal were the key flavor compounds of fresh coix seed oil, responsible for the grassy, oily, and watermelon-like smell of the oil. The deterioration of oil quality became more serious with the increase in oxidation time. The relative content of aldehydes was 73.815% after accelerated oxidation at 60 ℃ for 30 days, and the relative contents of small aldehydes, acids and alcohols were increased as compared with fresh oil. The key flavor compounds that were newly found in the accelerated oil included the newly added nonanal, octanal, hexanal, and (E)-2-octenal, which had a rancid odor due to the present of these compounds. Linear discriminant analysis (LDA) of the electronic nose data clearly distinguished the fresh oil from the oxidized oil, as well as between flavors in the early and late stages of oxidation. The characteristic compounds of fresh coix seed oil included (E)-2-nonenal, and (E,E)-2,4-decadienal. Small molecules, including nonanal, octanal, and hexanal, were the characteristic volatile compounds after accelerated oxidation of coix seed oil.