Aqueous enzymatic extraction technology of oil and protein hydrolysates from rapeseed

To obtain rapeseed free oil and protein hydrolysates simultaneously, wet-milled rapeseed slurry was treated with complex cell-wall polysaccharides degrading enzymes and Alcalase 2.4 L sequentially. Results show that the total extraction rates of free oil and protein hydrolysates are 88%～90% and 93%～95%, respectively, after combination of optimized enzyme hydrolysis(complex cell-wall polysaccharides degrading enzymes: enzyme concentration 3%(v/w), pH 5.0, 48℃, 5 h; Alcalase 2.4 L: enzyme concentration 1.5%(v/w), initial pH 9.0, 60℃, 3 h), washing and demulsification steps. Compared with solvent-extracted oil, the content of free fatty acid of enzyme-extracted oil is higher while the peroxide value is lower. The color of enzyme-extracted oil is slightly darker than that of solvent-extracted oil. The iodine value, saponification value and fatty acid composition between them are similar. Protein hydrolysates are composed of about 96% of peptides less than 1500 Da, of which about 87% are less than 600 Da. Protein hydrolysates are purified by macroporous adsorption resin. The sugar and ash contents of protein hydrolysates are significantly reduced and no glucosinolates and phytic acid are detected after purification.