PROTEINS FROM DOUBLE-ZERO RAPESEED

Solubility profiles of protein, phytic acid, and glucosinolates in aqueous electrolytes of varying pH were found to be similar for defatted meals from two varieties of double-zero (low glucosinolate/low erucic acid) rapeseed (Brassica napus) and conventional Chinese rapeseed (Brassica juncea). All three meals yield upon extraction with aqueous electrolytes at pH 4-5 products that are enriched in protein to the extent of 20-35%. Simultaneously, the level of phytic acid in the extracted meals is reduced by about one-third while the glucosinolates are virtually eliminated. Extraction of the defatted meals at pH 12-13 results in dissolution of >90% of the protein, one-third of the phytic acid, and <10% of the glucosinolates. The resulting extract provides upon precipitation of the protein at pH 4-5 protein isolates (>90% protein) in yields of about 60% having phytic acid content of 2-2.5% without any detectable levels of glucosinolates. The amino acid compositions of the meals and protein isolates indicate favorable nutritive value of such products. © 1990, American Chemical Society. All rights reserved.