Nutrition quality of frying fats in commercial use

Abstract

Summary and ConclusionsPublications on fats heated in the laboratory have been critically reviewed, and many of the these have been shown to present findings irrelevant to commercial frying operations. Just about two weeks before the delivery of this paper Rice and associates (22) independently reported before the American Institute of Nutrition on the nutritive value of frying oils in commercial use. They too were critical of the results of studies of highly unsaturated fats heated under unrealistic, arbitrarily selected, laboratory conditions. Conclusions based upon such laboratory studies should not be extended beyond the scope of the findings reported.The present report has presented the results of a nation‐wide survey of the frying oils in use on a continuing basis in the potato chip industry. Whereas a 1% decrease in iodine value has been found in the heated oils, this change has been shown to have no nutritional significance. The constancy in composition of the frying oils, heated as compared to fresh, and the results of physico‐chemical studies support the conclusion that neither thermal polymers nor thermal oxidative polymers are present in the oils employed in the commercial frying operations. Notrans fatty acids develop during the heating operations.The changes in linoleic acid content, the essential fatty acid in vegetable oils largely responsible for the important noncaloric functions of fat in the diet (23,24), are too small to have nutritional significance. This permits the same conclusions to be made in regard to the nutritive value of the heated oils,i.e., of the triglycerides contained therein, as have been drawn from studies conducted on the corresponding fresh oils.