Re: how I can make soy protein ?

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.