Extraction and residual antinutritional components in protein fractions of Sinapis alba and Brassica napus oil-free meals

Proteins were sequentially extracted from Australian canola (Brassica napus) and mustard (Sinapis alba) meals and two industrial canola meal samples, according to Osborne method (OSB), based on their solubilities in water, 5% NaCl, 0.1 M NaOH and 70% ethanol. These extracts were then compared to the glutelin fraction obtained by direct alkaline extraction method (DIR) in terms of protein yield, recovery, and residual antinutritional components. The OSB method was found to be more effective for protein extraction which resulted in higher cumulative protein yield and recovery of water-soluble protein fractions, although the DIR method produced a glutelin fraction of higher protein content. Phenolic compounds were observed in all the extracted protein fractions although sinapine, the major phenolic compound in canola, was present only in the albumin fractions. The glucosinolate content of all extracts was below the detection limit of the method employed (<3 'mol/g). Residual antinutritional components in protein fractions extracted from S. alba meal were, in general, higher than those of B. napus meal.