RAPESEED MEAL-GLUCOSINOLATES AND THEIR ANTINUTRITIONAL EFFECTS .6. TAINT IN END-PRODUCTS

From the present review it is clear that glucosinolates and their brea kdown products may pass in small amounts into such products as meat, m ilk or eggs without noticeable deterioration in their taste. When appl ying low glucosinolate rapeseed meal (LG-RSM) as the sole high protein component of concentrate mixture for cows, the level of rapeseed gluc osinolates breakdown products should not exceed 0.1 mu mol/l oxazolidi nethione, 10 mu mol/l unsaturated nitriles and 100 mu mol/l thiocyanat e. At these levels no evidence has been found to indicate the negative influence of glucosinolates breakdown products on the sensory propert ies of milk or threat for consumers. No published information appears to be available suggesting that glucosinolates have any deleterious ef fect on the carcass flavour in cattle. Even at a 20% inclusion of LG-R SM in diets no impairment on visual scores or sensory evaluation was f ound in pig's or broiler's carcass. Glucosinolated, chiefly progoitrin , which depress trimethylamine oxidation thus clearly affect the taint in eggs. In birds with genetically conditioned susceptibility (brown layers) fishy taint can be observed even at 0.3 mu M, progoitrin, i.e. approximately 0.5 mu M, total glucosinolates in 1 g diet. Assuming a threefold higher threshold for white layers (1 mu M progoitrin in Ig d iet) fishy taint can be expected at a 10% LG-RSM level in diet, and on ly very low glucosinolate rapeseed meals can be fed to layers without the risk of fishy taint in eggs.