RAPESEED PROTEIN-CONCENTRATE PREPARATION AND EVALUATION

Rapeseed is a major oilseed crop in Canada. Many investigators have turned their attention to use of protein left in the meal after oil extraction. However, the meal contains goitrogenic substances which must be removed or inactivated before the meal can be used as a potential protein source for food and feed. A water extraction process has been developed which removes over 90% of the glycosinolates and which results in a protein concentrate having an essential amino acid balance that has been shown by nutritional evaluation to be superior to any other known oilseed protein. However, in highly stressed animals being fed rapeseed protein as the only protein source, a zinc deficiency readily manifests itself, especially with pregnant rats. The zinc deficiency syndrome is readily overcome by supplementing the diets of pregnant rats with zinc in amounts sufficient to complex the phytic acid present in the protein concentrate. This approach appears to be more practical for overcoming the adverse effects of phytates than attempting to remove them by processing treatments. This contribution demonstrates the extensive studies necessary before a protein from a source known to possess toxic and antinutritional factors can be accepted as a food ingredient. © 1979 American Oil Chemists' Society.