Reaction principle: ignite brine with brine or gypsum. Brine mainly contains magnesium chloride, and gypsum is calcium sulfate, which can make dispersed protein particles quickly gather together (that is, colloid aggregation) and become glistening bean curd. Squeeze the water out again, and the tofu brain will become tofu. Tofu and tofu brain are both concentrated bean protein.

Brine is an aqueous solution of crystallized magnesium chloride, which belongs to electrolyte solution. It can neutralize the ionic charge adsorbed on the surface of colloidal particles, and make protein molecules condense to obtain tofu. ?

Extended data:

To turn colloidal solution into tofu, you must order brine. Bittern or gypsum is used to ignite bittern. Brine mainly contains magnesium chloride and gypsum is calcium sulfate. They can make the dispersed protein particles quickly gather together, that is, colloid aggregation, and become glistening tofu. Squeeze the water out again, and the tofu brain will become tofu. Tofu and tofu brain are both concentrated bean protein.

The scientific name of brine is bittern, which is the mother liquor left in the salt pond after being salted by seawater or salt lake water. The main ingredients are magnesium chloride, calcium sulfate, calcium chloride and sodium chloride, which tastes bitter. After evaporative cooling, magnesium chloride crystals are precipitated.

Coagulant commonly used in making tofu in northern China can make protein in soybean milk solidify into gel and analyze moisture. Tofu made of brine as coagulant has strong hardness, elasticity and toughness, and is called old tofu, or north tofu and hard tofu.