Fatty Acid Changes in High Oleic Acid Sunflower Oil during Successive Deep-Fat Fryings of Frozen Foods

Abstract

High oleic acid sunflower oil (HOSO) is a monounsaturated oil that is being extensively used in frying. The level of total altered fatty acids and the fatty acid pattern of a fryer oil was used to evaluate the alteration of a HOSO used 20 times to fry various frozen foods with frequent replenishment (FR) or without replenishment (NR) with fresh oil during the frying. In addition, the levels of total altered fatty acids and the fatty acid composition of the fat extracted from the fried potatoes after numerous fryings were determined and compared to those of the corresponding fryer oils. Altered fatty acids increased linearly through 20 fryings within FR and NR in the frying oil and also in the fat extracted. Although differences were not quantitatively relevant, changes tended to be higher in the extracted fat, and in the NR modality as a consequence of oil renovation and fat exchange between the frying oil and the potatoes. The decrease in the oleic acid content in the oil was more pronounced (p< 0.001) in NR than in FR method, and more (at least p< 0.01) in the oils than in the corresponding extracted fats. Nevertheless, other fatty acids remained quite stable and similar or increased during frying, by both methods. These results suggest that total fatty acid alteration measure is a useful tool for frying assessments, and that they must be related not only to the degradation of unsaturated fatty acids but also to migrations of some fatty acids from the frozen prefried foods to the fryer oil as revealed by composition of the fat extracted from the fried potatoes.