There is still a difference between the two. The main component of brine is magnesium chloride, and brine solution belongs to electrolyte solution, which will form many charged particles, positive ions and negative ions in water. The hydration of these ions captured the water film in protein and separated protein. In addition, the positive and negative ions of magnesium chloride electrolyte inhibited the repulsion generated by the surface charge of protein, and made the particles agglomerate with each other, thus becoming a mass of bean curd.

Brine brine is a brine block formed by crystallization of residual mother liquor in the salt pond after salt is made from seawater or salt lake water. Besides magnesium chloride, it also contains sodium chloride, potassium chloride, calcium chloride, magnesium sulfate and other components.

Gypsum is calcium sulfate. Besides brine and gypsum, other substances that meet the solidification conditions of protein can also be used as catalysts for tofu.

These two kinds of tofu are not exactly the same color. Brine tofu is slightly yellow in white and rough in texture, commonly known as old tofu, north tofu and hard tofu. Gypsum tofu is white in color and tender in texture, commonly known as tender tofu.

Brine tofu tastes hard, contains less water and smells like beans. Gypsum tofu tastes soft and tender, with a little more water and insufficient bean flavor.

Generally, northerners are used to ordering tofu with brine, while southerners are used to ordering tofu with gypsum.

Although brine tofu tastes healthy, it is difficult to operate and the finished product rate is low.