Novel method for the production of pure glycinin from soybeans

A novel method for the purification of glycinin from soy meal is presented. The method is based on the isoelectric precipitation of glycinin by using carbon dioxide as a volatile precipitant. Gaseous CO₂ was pressurized into the protein solution, thus lowering the pH and initiating glycinin precipitation. Pressurization and, consequently, acidification were done in a slow and controlled manner, with the end point of pH 6.4. The acidity of the protein solution was well controlled via the pressure of gaseous CO₂. In this way simultaneous precipitation of other soybean proteins was prevented and very pure glycinin was obtained. Approximately 40% of the glycinin present in the protein solution was recovered with purity as high as 98%. The purification process was successfully performed on both small and large scales, without affecting glycinin purity.