The salt in the protein solution make protein precipitation as well as adjust the pH. Because salt is broken down into positively charged and negatively charged and combined with protein. The addition of small amounts of salt May make it more soluble protein. Or catching up with good water evacuation (salting in) and is soluble up to the peak. If more concentrated salt solution. Make protein precipitation (salting out) sample of protein precipitation with a salt solution is to produce tofu. Which was prepared from soy milk. Then precipitated proteins suspended in soy milk with salt. Adjusting the pH (pH) to equal the isolation dielectric (isoelectric point), the pH of the protein are positively charged and negatively charged equally. Protein molecules are attracted to each other and suspended in the water at least. And precipitated out If proteins are dissolved in water. It causes high viscosity or gel.