Removal of Phenol and Glucosinolate from Rapeseeds with Acidic Ethanol and Its Effect on Protein Quality

The process of removing polyphenol and glucosinolate in the rapeseeds with acidic ethanol was investigated to detoxify rapeseed and improve protein quality. The protein was extracted from the water phase of the rapeseeds by the aqueous medium extraction processing of oil. In addition, the color, the purity and the functional properties of the phenolic and dephenolized protein was compared. The optimum extraction conditions were obtained as follows:40% (V/V) acidic ethanol (pH=5) as extraction solvent, solid-to-solvent ratio 1:5, temperature 80℃, for 3 times of extraction with 60 minutes each. Under the conditions, the extraction amount of polyphenol was (8.14±0.42) mg/g, and (32.28±2.32) mg/g for the glucosinolate. The removal rate of the polyphenol was 51.86%±2.31% and removal rate of the glucosinolate was 84.66%±0.76%, reaching the standard of glucosinolate-low rapeseed. Furthermore, the color of the dephenolized rapeseed protein became lighter, the purity increased from 57.24% to 63.63%. Furthermore, the water retention, oil retention, emulsification, emulsification stability, foaming stability, and foaming stability of the protein increased by 59.31%, 26.26%, 52.17%, 121.29%, 60.78%, 41.42%respectively, causing the functional properties of protein become better than the phenolic protein.