With defatted cottonseed meal as raw material, the method of alkaline extraction and acid pre-cipitation 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 or-thogonal 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 ba-sis ) , 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%.%以脱脂棉籽粕为原料,采用碱溶酸沉法制备棉籽分离蛋白。以蛋白质提取率、产品蛋白质含量为指标,考察提取温度、提取时间、pH、液固比对棉籽分离蛋白提取效果的影响。另外,采用SDS-PAGE对所制备棉籽分离蛋白中蛋白质亚基相对分子质量分布进行了分析。结果表明,通过正交实验优化得到棉籽分离蛋白最佳制备工艺条件为：提取温度60℃,提取时间60 min,pH 10,液固比14∶1。在最佳工艺条件下,蛋白质提取率为73．21%,产品蛋白质含量为90．76%( N ×6．25,干基),且游离棉酚含量由原料的0．12%下降到0．033%。棉籽分离蛋白中蛋白质亚基相对分子质量主要为59．3 kDa与53．7 kDa,占47．66%。
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