Preparation and physical modification of cottonseed protein concentrate

With low- temperature desolventized cottonseed meal as raw material,the cottonseed protein concentrate was prepared by ethanol washing method. The effects of volume fraction,washing temperature,washing time and washing times of ethanol and ratio of solid to liquid on protein content of cottonseed protein concentrate were investigated. The optimal preparation conditions were obtained as follows:volume fraction of ethanol 70%,washing temperature of ethanol 50 ℃,washing time of ethanol 20 min for three times,ratio of solid to liquid 1∶ 7. Under the optimal conditions,the protein content of cottonseed protein concentrate prepared was 68. 25%( N × 6. 25,dry basis),and the content of free gossypol falled to 0. 035 4%. The physical modification conditions of ethanol washed cottonseed protein concentrate,such as hot water temperature,mashed homogenization time,p H of protein solution and ultrasonic time were studied to improve the solubility of the product. The optimal physical modification conditions were obtained as follows: hot water temperature 95 ℃,mashed homogenization time 10 min,p H of protein solution 9,ultrasonic time 15 min. Under the optimal conditions,the NSI of modified cottonseed protein concentrate prepared increased from 12. 30% to 26. 59%,which was higher than 24. 46% of cottonseed meal.