The Characters And Discrimination Of Used Edible Oil

The discrimination of used edible oil was studied by determination of peroxidevalue, acid value, cholesterol content and fatty acid component, and estimation ofthese characters in this thesis. The paper consists of three chapters including thefollow contents:Chapter1, the utility of used edible oils and dietary harms to human health wereintroduced firstly. Then we review briefly the studies of some characters of usededible oils for discriminating. The deficiency and blank of study about discriminationof used edible oils was focused on in this part.Chapter2, the peroxide value, acid value, cholesterol content and fatty acidcomponent of the used edible oils which derive from different category weredetermined for estimation the quality of used edible oils. The results show that thequality of used edible oils degraded more or less. The peroxide value and acid valueof used edible oils were out of the quality and health standards range for edible oils.However, the content of peroxide value or acid value varied with the source of usededible oils. The cholesterol was determined in most of used edible oils. But thecontent of cholesterol varied with the source of used edible oils too. The amount andcontent of saturated fatty acids of used edible oils were larger than good-qualityvegetable oils. It is evident that the fraction of unsaturated fatty acids decreasedcorrespondingly. The content of trans fatty acids showed an increased trend as well.EPA and DHA that exist in fish oils but do not exist in vegetable oils were determinedin some used edible oils.Chapter3, the discrimination with the characters of cholesterol and fatty acidscomponent of used edible oils was studied. The method of this discrimination withcholesterol content meets the used edible oils that were contaminated by thecholesterol in animal food. It is feasible and simple. The method of discriminationbased on fatty acids component is established by distinguishing with the amount andcontent of fatty acids. The category of fatty acids of used edible oils had an increasedtrend. These fatty acids involved in short carbon train fatty acids, trans fatty acids, andother fatty acids which do not exist in vegetable oils. The amount of short carbon trainfatty acids increase too. Moreover, the ratio of unsaturated fatty acids to saturated fatty acids decreased in the used edible oils. The discrimination of used edible oilswith characters of fatty acids was feasible. The used edible oils were easy todistinguish from vegetable oils.