What is the principle of changing soybean milk into tofu?

1. Tofu is made by soaking soybeans in water to make them swell and soften, grinding them into soybean milk in a stone mill, filtering out bean dregs and boiling them. At that time, protein particles in soybean were surrounded by water and kept moving, just like dancing in a soybean milk bucket, but they could not get together to form a "colloidal" solution. But in order to turn the colloidal solution into tofu, you must order salt water. Bitter bittern or gypsum is used to ignite bittern. Brine mainly contains magnesium chloride, and gypsum is calcium sulfate, which can make dispersed protein particles quickly gather and become shiny tofu. Squeeze the water out again, and the soybean milk will become tofu.

Second, this is the same principle as ordering brine tofu. South tofu is mainly made of gypsum, and its composition is calcium sulfate. Beidoufu uses brine as coagulant, and the main component of brine is magnesium chloride. The basic principle is electrostatic action. After heating, the surface of soybean milk is negatively charged, and divalent salt ions can induce protein to aggregate to form gel.

3. Soybean, the raw material of tofu, is rich in protein and contains 36% ~ 40% protein. Protein colloid (a mixture of solution, suspension and emulsion) is obtained by soaking in water, grinding, deslagging and heating. The purpose of ordering tofu is to make protein as solidified as possible and separate from water. Saline is an aqueous solution of crystalline magnesium chloride [[magnesium chloride ·6H2O]]], which belongs to electrolyte solution. It can neutralize the ionic charge adsorbed on the surface of colloidal particles, and make protein molecules aggregate to obtain tofu.

4. Because tofu is used to solidify protein, the gel used is not necessarily brine. Others, such as gypsum, ester acid, citric acid, etc. Both have the same effect and can be used to order tofu. In addition, it is worth mentioning that in recent years, there is a kind of boxed tofu on the market. This kind of tofu is white and delicate, and its quality is obviously higher than that made by traditional methods. Initially, its coagulant used a new chemical substance-gluconolactone, which is also an example of the application of new technology in food processing.

5. What is the function of gypsum when making tofu?

Gypsum is an electrolyte. The so-called "point" tofu is to add enough electrolyte to the protein colloid and neutralize the negative charge of the protein colloid particles with positively charged calcium and magnesium ions in the electrolyte. Because there is no electrostatic repulsion between protein molecules, the dispersed protein colloidal particles aggregate and precipitate into tofu. This process is called "colloidal precipitation" and is a physical process without chemical reaction. Finally, tofu is squeezed out of the water and turned into tofu. Soymilk and tofu are both concentrated soy protein. Gypsum is mainly composed of calcium sulfate with a small amount of silicic acid and aluminum hydroxide. Tofu solidified with gypsum has a moisture content of about 90% and a delicate texture.