压榨菜籽油加速氧化过程挥发性成分变化分析

采用顶空固相微萃取-气质联用和电子鼻技术，对一级压榨菜籽油（S1）和四级压榨菜籽油（S2）在60 ℃加速氧化下的挥发性风味成分进行了分析，并分析其与品质指标的相关性。结果表明:S1和S2的酸价与酸类化合物有关；醛类化合物含量与氧化劣变程度有着重要关联，S1的过氧化值总体上高于S2；经20 d加速氧化后，S1的茴香胺值高于S2；S1在氧化前期的氧化速率高，S2在氧化后期的氧化速率高，表明S1的劣变程度高于S2。菜籽油在加速氧化期间主体挥发性成分主要为醛类化合物，S1加速氧化20 d的特征风味成分是壬醛、癸醛、2,4-癸二烯醛和2-癸酮；S2加速氧化20 d的特征风味成分是（E）-2-癸烯醛。电子鼻雷达图能区分未氧化油与氧化油以及氧化初期及后期风味成分的差异。(E)-2-癸烯醛、(E)-2-壬烯醛、辛醛和2-十一烯醛含量与S1的过氧化值、茴香胺值和总氧化值相关；壬醛、(E,E)-2-4癸二烯醛、(E)-2-癸烯醛、(E)-2-壬烯醛、癸醛、辛醛和庚醛含量与S2的过氧化值、茴香胺值和总氧化值相关。挥发性成分可作为监测菜籽油在储藏过程中氧化程度的标志。

Analysis of Volatile Compounds Changes during the Oxidation of Pressed Rapeseed Oil

Volatile flavor components of first-grade pressed rapeseed oil (S1) and fourth-grade pressed rapeseed oil (S2) subjected to accelerated oxidation test at 60 ℃ were profiled by means of headspace solid-phase microextraction with gas chromatography-mass spectrometry (HS-SPME-GC-MS) coupled with electronic nose (E-nose) technology, followed by correlation analysis with quality indicators. The results showed that the acid value of S1 and S2 was related to acid compounds. The content of aldehyde compounds had an important correlation with the degree of oxidation deterioration. The peroxide value of S1 was generally higher than that of S2. After 20 d of accelerated oxidation, S1 had a higher anisidine value than S2. S1 had a high oxidation rate in the early stage of oxidation, and S2 had a high oxidation rate in the later stage of oxidation. It showed that the deterioration degree of S1 was higher than that of S2. The main volatile components of rapeseed oil during accelerated oxidation were mainly aldehydes. The characteristic flavor components of S1 accelerated oxidation for 20 days were nonanal, decanal, 2,4-decadienal and 2-decanone. The characteristic flavor components of S2 accelerated oxidation for 20 days were (E)-2-decenal. The E-nose radar chart could distinguish unoxidized oil and oxidized oil, as well as the difference in flavor components in the early and late stages of oxidation. The content of (E)-2-decenal, (E)-2-nonenal, octanal and 2-undecenal were related to the peroxide value, anisidine value and total oxidation value of S1. The content of nonanal, (E,E)-2-4 decenal, (E)-2-decenal, (E)-2-nonenal, decanal, octyl aldehyde and heptanal were related to the peroxide value, anisidine value and total oxidation value of S2. Volatile components can be used as indicators to monitor the oxidation degree of rapeseed oil during storage.