Preparation of Rapeseed Protein Isolate by Sodium Hexametaphosphate Extraction, Ultrafiltration, Diafiltration, and Ion‐Exchange

A novel processing scheme for the production of rapeseed protein isolate was developed which includes extraction using aqueous sodium hexametaphosphate solution followed by activated‐carbon treatment, ultrafiltration, diafiltration, and purification by ion‐exchange. Aqueous sodium hexametaphosphate is an effective extraction agent for rape‐seed proteins. The activated‐carbon treatment removes glucosinolate hydrolysis products and color compounds. The membrane treatments reduce the concentration of soluble low‐molecular‐weight components to low levels. An anion exchange resin was used in the last step to remove phytate and residual hexametaphosphate. The process resulted in a protein isolate containing about 90% protein. Sixty‐three per cent of the nitrogen in the meal was recovered as an isolate free of glucosinolates, low in phytates and fiber, light in color, and bland in taste.