Brine tofu is tofu made with bittern (magnesium chloride), and gypsum tofu is tofu made with calcium sulfate. Brine tofu tastes soft and tough, with bean flavor, less water content, slightly yellowish white color and coarse texture. It is commonly known as "old tofu" and "north tofu" and is mainly used for frying, frying, brewing and stuffing. Gypsum tofu is tender, smooth, rich in water and white in color, commonly known as "tender tofu" and "southern tofu", and is mainly used for mixing, stewing, roasting and making soup and soup dishes. Tofu classic dishes, such as "spring onion mixed with tofu", "Mapo tofu", "pot-pasted tofu", "casserole tofu" and "loach-drilled tofu", are healthier. In the market, there are more tofu made of gypsum, and gypsum tofu is whiter than brine tofu. Brine tofu tastes soft and tough, with bean flavor, while gypsum tofu is tender and smooth. Experts believe that it is better to eat less gypsum tofu, because the additives in it are not good, and eating too much tofu is a physical burden for some elderly people, which increases the burden on their kidney organs.