Optimization of Extraction Method for Water-soluble Protein Determination by Coomassie Bright Blue Method

In order to improve the efficiency of extracting soybean water-soluble protein by Coomassie brilliant blue method, the protein extraction condition for determining the content was optimized with high-quality, high protein soybean variety Jidou 12 in Hebei Province as material. On the basis of single factor test, the effects of four factors such as material liquid ratio, extraction temperature, extraction time and rotating speed on the determination results of soybean water-soluble protein were analyzed by orthogonal test method, and an accurate, efficient and reproducible method system suitable for soybean variety identification in Hebei Province were selected. The content of water-soluble protein in 29 soybean materials in Hebei Province were determined by the optimized extraction method. The results showed that the optimized extraction conditions were as follows: Solid-liquid ratio 1∶400, extraction temperature 30 ℃, extraction time 90 min and rotating speed 220 r·min^-1. The water-soluble protein content of 29 new soybean materials harvested in the autumn of 2020 in Hebei Province were determined by using the optimized system. The water-soluble protein content of three materials were 15%-20%, seven materials were 20%-25%, five materials were 25%-30%, and fourteen materials were more than 30%.