Why do you want to use brine to make tofu?
If you pay attention to the situation of making tofu in the tofu shop, you will find that people always soak soybeans in water, grind them into soybean milk, boil them, and then add brine to the soybean milk. At this time, many glistening things are separated, and once filtered, they are made into tofu.
Since brine can't be drunk, why use brine to make tofu?
It turns out that the main chemical component of soybean is protein. Protein is a polymer compound composed of amino acids, and the surface of protein has free carboxyl and amino groups. Due to the action of these groups on water, a layer of water film colloidal substance with the same charge is formed on the surface of protein particles, so that the particles are isolated from each other and will not sink due to collision.
When bittern is ignited, because bittern is electrolyte, it will split into many charged small particles-positive ions and negative ions. Due to the hydration of these ions, the water film in the protein was seized, so there was not enough water to dissolve protein. In addition, the positive and negative ions of salt inhibited the repulsion generated by the surface charge of protein, reduced the solubility of protein, and the particles condensed into precipitates. There are many shiny things in soybean milk at this time.
There are many electrolytes in brine, mainly metal ions such as calcium and magnesium, which will solidify protein in human body. Therefore, if people drink more brine, their lives will be in danger.
Tofu workshops sometimes use gypsum instead of brine, and the same is true.