Use "“""salt brine”"as a coagulant!Southtofuis made with gypsum as the coagulant, whilenorthtofuis made with salt brine.Evaporate and cool to precipitate magnesium chloride crystals.These are called halite blocks.Halite blocks dissolve in water to formbrine,which is commonly used as a coagulant for making tofu in northern China, causingproteinsolutions toTofu made with salt brine has a stronger hardness, elasticity, and toughness, known as old tofu or north tofu, hard tofu.When using salt brine as a coagulant, the concentration is generally 18～22°Be′, with an amount of about 2%～3.5% of the weight of raw soybeans.The way to add brine is: continuously add fine streams of salt brine while stirring the heatedsoymilk,or intermittently add salt brine to the heated soymilk with a certain time interval between additions.Salt brine can also be intermittently added to the cooked soy milk, with a certain time interval in between.