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Prevention of rancidity in experimental rat diets for long-term feeding

Warner, K., Bookwalter, G.N., Rackis, J.J., Honig, D.H., Hockridge, E., Kwolek, W.F.
Cereal chemistry 1982 v.59 no.3 pp. 175
feeds, experimental diets, casein, spoilage, rancidity, odors, off odors, aldehydes, antioxidants, butylated hydroxyanisole, laboratory animals, rats
Experimental rat diets containing casein as the sole protein source were aged at 24 and C for 6 mo. Test variables included antioxidant effect and types of casein, fat and Fe. 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 2 aldehydes after 4 days of storage at C and after 8 days of storage at C. Neither Fe 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.