大豆分离蛋白的提取、纯化及鉴定

Extraction,purification and identification of soybean protein isolate

以大豆粉提油后的豆粕为原料,采用碱溶酸沉法提取大豆分离蛋白。以浸提pH、料液比、浸提温度、浸提时间为考察因素,运用单因素试验和正交试验确定大豆分离蛋白的最佳提取工艺条件,再经5次沉淀和凝胶过滤制得纯化蛋白质,并利用凯氏定氮法和SDS-PAGE法鉴定其纯度。结果表明:在碱液pH 8、料液比1∶14g/mL、浸提温度50℃、浸提时间60min时,大豆分离蛋白的提取率达到82.58%,粗蛋白提取物中蛋白质含量为92.65%。凝胶过滤的目标蛋白图谱呈现单一洗脱峰,SDS-PAGE图谱只存在少量杂带,纯化后的总蛋白含量为98.56%。

Soybean protein isolate was extracted by alkali solution and acid precipitation from meal after oil extraction.The optimum extraction conditions were determined by single factor experiment and orthogonal experiment of extraction pH,solid-liquid ratio,extraction temperature and extraction time. 5 times of precipitation and gel filtration was needed to obtain purified protein. The purity of the product was determined by Kjeldahl nitrogen and SDS PAGE method. The results showed that the optimal extraction conditions were :extraction pH 8,solid-liquid ratio 1∶14g/mL,extraction temperature 50℃ and extraction time 60min. Under these conditions,the extraction rate of soybean protein isolate reached 82.58%. The protein content in crude protein extract was 92.65%. The target protein profile of gel filtration showed a single elution peak,and the SDS-PAGE profile had only a few contaminants,and the total protein content after purification was 98.56%.