Cereal Chem 59:175 - 178.  |  VIEW ARTICLE
Prevention of Rancidity in Experimental Rat Diets for Long-Term Feeding.

K. Warner, G. N. Bookwalter, J. J. Rackis, D. H. Honig, E. Hockridge, and W. F. Kwolek. Copyright 1982 by the American Association of Cereal Chemists, Inc. 

Experimental rat diets containing casein as the sole protein source were aged at 24 and 37 C for six months. Test variables included antioxidant effect and types of casein, fat, and iron. Samples were analyzed by a trained, experienced sensory panel for rancid odor intensity and by gas chromatography for pentanal and hexanal formation. Antioxidants in the diets effectively prevented rancid odor development and formation of pentanal and hexanal. Diets without the antioxidant combination of butylated hydroxyanisole and tertiary butylhydroquinone developed rancid odors and generated large amounts of the two aldehydes after four days of storage at 37 C and after eight days of storage at 24 C. Neither iron nor fat type had a significant effect on rancid odor development or on the content of aldehydes in the aged diets. The diets containing vitamin-free casein (alcohol-washed) had higher intensities for rancid odor and greater contents of pentanal and hexanal than did diets prepared with regular lactic casein. Logs of pentanal and hexanal contents correlated significantly with odor intensity values for rancidity in diets without antioxidants.