Destruction of Vitamin A by Rancid Fats

Abstract

Rancid fats were found to destroy pure carotene and vitamin A or precursors thereof as contained in halibut liver oil, egg yolk, or alfalfa. Ozonized fats and palmitic peroxide also destroyed vitamin A. Fats which had been heated at such temperatures as are frequently used in cooking were found to destroy vitamin A to some extent. Vitamin A was not destroyed by oxidized glycerol, glyceric acid, glyceric aldehyde, allyl alcohol, acrolein, acrylic acid, pyruvic acid, propyl aldehyde, straight-chain aldehydes and methyl ketones of 7 to 12 carbon atoms, or decomposition products formed in the commercial hydrogenation of fats or by fresh fats heated in the absence of oxygen. The components of rancid fats which caused destruction were not removed by distillation with steam nor extraction with alcohol. Heating of rancid fats lowered both their capacity to destroy vitamin A and their peroxide value. The addition to rancid fats of ascorbic acid, hydroquinone, gallic acid, and ethyl gallate as antioxidants did not prevent the destruction of vitamin A. Vitamin A was not destroyed when given to rats on an empty stomach even though they were being maintained on a ration rich in rancid fat. Peroxides of rancid fats were stable for as long as 4 hours in the stomach, and destruction occurred when vitamin A and rancid fat were combined here for the first time.