The influence of temperature, heating time, and aeration upon the nutritive value of fats

Abstract

AbstractIn order to determine the biological significance of the changes which occur when fats are heated to high temperatures in air, cottonseed oils were heated and aerated under several controlled conditions. In general, the data indicate that the changes induced are proportional to the severity of the conditions and that treatments more severe than those usually encountered in processing or cooking are necessary to produce detectable damage.Oils which had been subjected to prolonged aeration at 60C (16 days or more) or exposed to air in thin layers maintained at 180舑220C supplied less available energy and caused development of larger livers than untreated samples when compared in rat feeding tests. Heating in deep layers caused less damage than heating to the same temperatures in thin films, indicating that exposure to oxygen accelerates nutritional impairment.The cooking of food in fats changes condition so greatly that direct extrapolation of data obtained in tests using fat alone is not justified. Fat extracted from foods has not been found to contain harmful substances by the tests used.