|MadSci Network: Agricultural Sciences|
Making soy protein is not usually done other than commercially. Generally the soybeans are dehulled. The remaining material is then solvent extracted to remove the oil -- which is the major commercial ingredient obtained from soybeans. This gives soy flour. To further concentrate the protein, the starch can be removed by an acid wash. This gives soy protein concentrate. Using alkali, the protein can be dissolved and then acid precipitated and this would give you an even more concentrated soy protein, now called soy protein isolate (SPI). Because of the complexity of the process, the isolate is significantly more expensive.
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