大豆热损对其油脂品质及组成的影响Effects of soybean heat damage on oil quality and composition

旨在为热损大豆的加工提供理论支撑，以不同热损程度的巴西大豆为原料，采用索氏抽提法制备大豆油，分析其酸值、过氧化值、茴香胺值、全氧化值、氧化诱导期、甘油酯和游离脂肪酸组成及含量、磷脂及生育酚组成及含量、色素含量，探明大豆热损对其油脂品质及组成的影响。结果表明：随着大豆热损程度的增加，其油脂的酸值、过氧化值、茴香胺值、全氧化值显著升高（p＜0.05），氧化诱导期显著下降（p＜0.05），与正常大豆相比，重度热损大豆油脂酸值和全氧化值的增长率分别高达557%、148%；热损导致大豆油水解，甘三酯相对含量降低，甘二酯和游离脂肪酸相对含量上升，以Sn-1,3位水解为主；氧化反应导致多不饱和脂肪酸相对含量显著降低（p＜0.05），且热损程度越深变化越明显；热损导致大豆油总磷脂含量下降，磷脂酸相对含量显著上升，生育酚含量降低，重度热损大豆油脂中总生育酚的损失率高达19%；未成熟大豆更易发生热损现象，不同热损程度大豆油脂中的叶绿素、叶黄素及β-胡萝卜素含量具有显著性差异（p＜0.05）。综上，大豆热损会导致其油脂组成发生变化，品质降低。In order to provide theoretical support for the processing of heat damaged soybean, using Brazilian soybean with different degrees of heat damage as raw materials, soybean oil was extracted by Soxhlet extraction method. The acid value, peroxide value, anisidine value, total oxidation value, oxidation induction period, composition and content of triglyceride and free fatty acids, composition and content of phospholipids and tocopherol of soybean oil, and pigment content were analyzed to explore the effects of soybean heat damage on it′s oil quality and composition. The results showed that with the increase of heat damage, the acid value, peroxide value, anisidine value and total oxidation value of soybean oil significantly increased (p<0.05), and the oxidation induction period significantly decreased (p<0.05). Compared with normal soybean, the increase rates of acid value and total oxidation value of oil from severely heat damaged soybean were up to 557% and 148%, respectively. Heat demage led to hydrolysis of soybean oil, resulting in the decrease of triglyceride relative content and the increase of diglyceride and free fatty acids relative contents, and the hydrolysis reaction was dominated by Sn-1,3 hydrolysis.The oxidation reaction led to a significant decrease in the relative content of polyunsaturated fatty acids (p<0.05), and the severer the heat damage was, the more obvious the change was. Heat damage reduced the content of total phospholipids in soybean oil, and the phosphatidic acid relative content increased significantly. The tocopherol content decreased, and the loss rate of total tocopherol in oil from severely heat damaged soybean was up to 19%. Immature soybeans were more prone to heat damage, and the contents of chlorophyll, lutein and β-carotene in soybean oil were significantly different with different heat damage degrees (p<0.05). In general, heat damage of soybean will result in the change of oil composition and the decrease of quality.