Impact of high-temperature food processing on fats and oils

Fats and oils are heated at high temperatures during baking, grilling and pan frying; however, deep fat frying is the most common method of high temperature treatment. Deep fat frying is a popular food preparation method because it produces desirable fried food flavor, golden brown color and crisp texture. For example, in the U.S. in 1994, approximately 12 billion pounds of fats and oils were used with 5.5 billion pounds used for frying and baking (USDA, 1995). Fried snack foods accounted for 2.9 billion pounds of oil, whereas 2 billion pounds were used for frying in restaurants (USDA, 1995). Because of such large consumption of frying oils and fats, the effects of high temperatures on these oils and fats is of major concern both for product quality and nutrition. This chapter will discuss the process of frying and the chemical and physical reactions that occur. The products formed from these reactions will be reviewed as well as information on the effects of the products and the control of these deteriorative reactions.