EFFECT OF RANCIDITY OF LUPINUS-ALBUS PROTEIN-CONCENTRATE-BASED DIETS ON FOOD-INTAKE AND GROWTH OF WISTAR RATS

The organoleptic properties of a diet are influenced by technological processes and have to be taken into account in food intake studies. Th e authors studied the food intake suppression associated with rancidit y occurring during the storage of diets based on casein or heated or l yophilised lupin protein concentrates, and with or without ascorbic ac id supplementation in five groups of 10 weanling Wistar rats for 21 or 26 days. After 15 days of storage, the unsaturated fatty acids were o xidised in heated lupin-protein-based diet without ascorbic acid. Comp ared to casein, food intake was decreased slightly during the first 10 , 15 or 20 days for, respectively, heated lupin protein diet without a scorbic acid, heated lupin protein diet with ascorbic acid, and lyophi lised lupin protein diet with or without ascorbic acid, After these pe riods, food intake decreased strongly Body weight gain variations did not exactly follow food intake variations. The storage at 20 degrees C could induce first an accumulation of free radicals, which were not d etectable in measurement of fatty acids but perceived by rats, and the n a fast oxidation of unsaturated fatty acids that increased rancid sm ell, modified nutritional quality and caused a dramatic decrease of ra t food intake. Supplementing ascorbic acid into the diet could diminis h the formation of free radicals at the beginning of storage, and cons equently could delay food intake decrease.