| With defatted cottonseed meal as raw material, the method of alkaline extraction and acid precipitation was used to prepare cottonseed protein isolate. Using extraction rate of protein and content of protein as the indexes, the effects of extraction temperature, extraction time, pH and ratio of liquid to solid on the extraction of cottonseed protein isolate were considered. Moreover, SDS-PAGE was used to analyze the relative molecular weight distribution of protein subunit in cottonseed protein isolate prepared. The results showed that the optimal extraction conditions of cottonseed protein isolate were obtained by orthogonal experiment as follows: extraction temperature 60℃, extraction time 60 min, pH 10 and ratio of liquid to solid 14∶1. Under the optimal conditions, the extraction rate of cottonseed protein isolate reached 73.21%, the protein content of the cottonseed protein isolate was 90.76%（N×6.25,dry basis）, and the content of free gossypol reduced from 0.12% to 0.033%. The relative molecular weights of protein subunit in cottonseed protein isolate were main 59.3 kDa and 53.7 kDa, reaching 47.66%。 |
