Changes of oxidation indicators and fatty acid composition of six kinds of fats and soybean meal,rapeseed meal
In the artificial oxidation conditions,we measured acid value,iodine value,peroxide value,MDA and fatty acids of lard,soybean oil,soybean meal,rapeseed oil,rapeseed meal,cottonseed oil from Jiangsu and Xinjiang,and tilapia oil.The results indicate: ①Changes of measured oxidation indicators of tilapia oil were more obvious than other oil with the worst oxidation stability;②The indicator(POV) of lard,tilapia oil,cottonseed oil,rapeseed oil and soybean oil significantly changed in the oxidation process,therefore it should become the common evaluation indicators;③Changes of the oxidation indicators of soybean meal and rapeseed meal were the smallest,and the oxidative stability was significantly better than their corresponding oil;④ During the 70 hours period,with the extention of oxidation time,the fatty acid composition of the oil were not significantly changed.In the oxidation process,sensitive indicators of different types of fat are different.To evaluate oil oxidation,the indicators should be selected according to each type of fat.In the early stage of oil oxidation,it is not obvious to characterize the quality of the oil with the change of fatty acid composition.