EFFECT OF LIPID OXIDATION ON OIL AND FOOD QUALITY IN DEEP FRYING

Deep frying is a popular method for food preparation, especially in fast food restaurants. However, lipid oxidation easily occurs at relatively high temperatures in the presence of air and produces a multiplicity of compounds and exerts both desirable and undesirable effects on food flavor and quality. A low level of oxidation actually improves the desirability of a food but higher levels decrease food quality. The presence of low molecular weight materials such as aldehydes, lactones and pyrazines influence the flavor of deep fried foods such as potatoes; while the presence of high molecular weight materials contribute to the overall quality deterioration of both the frying fat and the fried product. The application of GC-MS to the determination of flavor components in french fries and corresponding frying oil yielded information indicating a relationship between the presence of these materials and french fry quality. A larger scale study in which the amounts of high molecular weight products were determined showed the time course of oil deterioration and a relationship between total polar material formed and food quality.