不同热损程度大豆油脂品质及组成分析

目的 探究不同热损程度大豆油脂品质与组成的差异性。方法 以同一批次含有热损现象的美湾大豆为研究对象,通过测定不同热损程度大豆油脂的酸价、过氧化值、茴香胺值、全氧化值、氧化诱导期、甘油酯及脂肪酸的组成以及微量成分(磷脂、生育酚、色素)含量的差异,分析大豆热损对油脂品质和组成的影响。结果 热损会导致油脂的品质显著下降,酸价、过氧化值、茴香胺值、全氧化值均随热损程度的增加显著上升,氧化稳定诱导时间显著降低;重度热损过程中油脂发生氧化和Sn-1,3位为主的水解反应,氧化反应主要导致多不饱和脂肪酸含量降低,水解反应导致甘三酯含量由95.71%下降至91.79%,甘二酯和游离脂肪酸含量显著上升;大豆热损导致油脂中的总磷脂含量下降,磷脂酸的相对含量显著上升,生育酚在热损过程中易发生氧化损失,总生育酚损失率高达11%。结合大豆外观、磷脂组成和色素含量分析,未成熟大豆易发生热损,导致油脂中叶绿素含量显著上升。结论 大豆热损会导致油脂的品质和组成差异显著,热损程度越深,油脂品质越差。

Quality and composition analysis of soybean oils with different degrees of heat damage

Objective To study the difference of soybean oil quality and composition in different degrees of heat damage. Methods The effects of soybean heat damage on the quality and composition of soybean oil were analyzed by measuring the acid value, peroxide value, anisidine value, total oxidation value, oxidation induction period, the composition of triglycerides and fatty acids and the content of trace components (phospholipid, tocopherols, pigments) of soybean oil with different degrees of heat damage. Results The quality of oil was significantly decreased by heat damage. The acid value, peroxide value, anisidine value and total oxidation value were significantly increased with the increase of heat damage degree, and the induction time of oxidation stability was significantly decreased. During the severe heat damage process, oxidation and Sn-1,3 hydrolysis reaction occurred in oil. The oxidation reaction mainly led in decrease in the content of polyunsaturated fatty acids, and the hydrolysis reaction reduced the content of triglyceride from 95.71% to 91.79%, resulting in the significant increase of diglyceride and free fatty acids content. Soybean heat damage resulted in the decrease of total phospholipids content in oils and the significant increase of relative content of phosphatidic acid. Oxidative loss of tocopherols was prone to occur during heat damage, and the total loss rate of tocopherols was as high as to 11%. Combined with the appearance of soybeans, phospholipid composition and the content of pigment, immature soybean was prone to heat damage, resulting in a significant increase of chlorophyll content in oil. Conclusion Soybean heat damage can cause significant difference in quality and composition of oil, the deeper the heat damage, the worse the quality of oil.