High oleic oils perform better than standard oils during frying.

The frying of a singular product, usually french fries, is frequently used as the testing procedure to assess performance of frying oils. In real frying, this approach is only performed for the large-scale frying of specific products. In an institutional frying operation, a variety of products are usually fried in the same fryer and frying medium: rotational frying. This approach used to assess oil performance more accurately mimics typical frying operations.

Canadian scientists assessed the performance of high oleic oils during the rotational frying of french fries, chicken and fish strips. The last two groups of products were buttered foods that further affected the performance of frying oils. The rate of formation of polar components was the highest in non-modified canola and soybean oils. However, high oleic oils caused a reduced amount of polar components to form.

A similar pattern was observed for carbonyls formation as measured by anisidine values. Once more for high oleic oils, the amount of formed carbonyl components was lower, compared to regular oils. All tested oils had similar amounts of trans fatty acid isomers--typical amounts formed during oil processing.

Endogenous antioxidants were present at the amounts specific for particular oils. However, the extent of their depletion during frying varied. Hydrogenated oils showed the highest rate of depletion, while high oleic oils usually exhibited the lowest.

The exchange of fat components between oil and fried products was the main factor that determined the nutritional quality of the latter. During frying, fried products picked up significant amounts of polar components and the composition of fatty acids changed according to their composition in the frying medium. High oleic oils showed much better performance during rotational frying than standard oils and hydrogenated shortening.

Further information. Roman Przybylski, Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Dr., E854 (University Hall), Lethbridge, Alberta T1K 3M4, Canada; phone: [phone]; fax: [phone]; email: [e-mail].