The production of Chinese rapeseed protein isolates by membrane processing

A membrane‐based process was developed for the production of Chinese rapeseed protein isolates, which consisted of alkaline extraction of protein at pH 12.0 from CH2OH/NH3/H2O‐hexane‐extracted Chinese rapeseed meal, isoelectric precipitation at pH 6.5, ultrafiltration followed by diafiltration to concentrate the remaining soluble protein, and freeze‐drying. No chemical treatment was required for the removal of phytates from the protein. Three products were obtained with high protein recovery: precipitated and soluble protein isolates, each containing 90 to 100% protein, suitable for animal feed. The two protein isolates were low in phytates, light in color and bland in taste. Chinese rapeseed protein was easier and more economical to treat than canola protein due to the shift of pH for isoelectric precipitation and the elimination of the need for further phytate reduction.