EFFECTS OF BIN-HEATING ON THE CHEMICAL COMPOSITION AND NUTRITIONAL VALUE OF RAPESEED FED TO MICE

Undamaged and bin-heated rapeseed (Brassica campestris) were either: ground; ground and dry-cooked for 30 min at 110 C; ground and autoclaved for 30 min at 1.2 kg/cm2, then dried at 100 C; ground, autoclaved, partially extracted with petroleum ether; or ground, autoclaved, extracted, steam-stripped, and dried. These meals were incorporated at 8, 12, 16, and 20% levels, seed basis, in approximately isocaloric, isonitrogenous mouse diets containing about 20% protein. Bin-heated rapeseed contained no glucosinolates, no myrosinase, and only a trace of hydroxynitriles, but had lost 65, 52, 28, 23, and 15% of its original tryptophan, lysine, histidine, arginine, and threonine, respectively. Mycotoxins were not detected. The odor of the meal derived from heated rapeseed was rated by a panel and found to be generally pleasant. Growth rates and feed utilization by mice fed bin-heated rapeseed were normal. Dietary protein levels were too high to allow the amino acid changes to be reflected in animal performance.