The scientific name of brine is bittern, which is also called bittern and bittern alkali. It is the crystallization of magnesium chloride after evaporating and cooling the mother liquor left in the salt pond after salting seawater or salt lake water, and brine is the aqueous solution of crystallization. Bittern is toxic, which has a strong stimulating effect on skin and mucosa, and has an inhibitory effect on the central nervous system. It cannot be eaten directly.

Expand the principle of making tofu with data

The main chemical component of soybean is protein. Protein is a polymer compound composed of amino acids, with free carboxyl and amino groups on the surface of protein. Due to the action of these substances on water, a layer of colloidal substances with water film 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.

However, when bittern is lit, because bittern is electrolyte, mainly metal ions such as calcium and magnesium, which will solidify protein in soybean milk. Bittern is divided into many small charged particles-positive ions and negative ions. Due to the hydration of these ions, the water film in protein is seized, so there is not enough water to dissolve protein.

In addition, the positive and negative ions of salt inhibit the repulsion caused by the charge on the surface of protein, which reduces the solubility of protein and makes the particles condense into precipitates, so that protein in soybean milk condenses into gel and becomes glistening tofu brain, and then the water is separated out to become tofu.

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Xinhuanet's "Bitter tofu" points out the food on the tip of the tongue "