Soybeans that make tofu are rich in nutrition. The following are the protein price comparisons of several main animal and plant protein foods (when the standard protein price is 100): egg 100, beef 83, fish 70, rice 67, whole wheat flour 53, corn 59 and soybean flour 74. It can be seen that the protein price of soybean is equivalent to that of fish and is the best among plant proteins. Soybean protein is completely protein, with good amino acid composition and eight essential amino acids. Except for protein, the oil content of soybean is about 18%, and most of it can be transferred to bean products.
Soybean oil has a large proportion of linoleic acid (the main fatty acid necessary for human body) and contains no cholesterol, which is not only beneficial to the development of nerves, blood vessels and brain, but also can prevent common diseases such as cardiovascular disease and obesity. Soybeans also contain some protease substances, saponins and vitamin-destroying components, which have adverse effects on human health, but they can be eliminated as long as they are heated properly. On the other hand, when soybean is directly made into food, the protein digestibility of human body is only 65%, but after being made into tofu, the digestibility can be increased to 92% to 95%. It can be seen that tofu is the most beneficial to people in the soybean family.
Soak soybeans in water, swell and soften, grind them into soybean milk in a stone mill, then filter off bean dregs and boil them. At this time, the protein particles in soybean are surrounded by water and keep moving, as if dancing in a group in a soybean milk bucket, but they can't get together and form a "colloid" solution. 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, which can make dispersed protein particles quickly gather together and become shiny bean curd. Squeeze the water out again, and the tofu brain will become tofu. Tofu and tofu brain are both concentrated bean protein.
When we drink soybean milk, we sometimes repeat the process of making tofu. Some people like sweet syrup. Soymilk with a spoonful of sugar has not changed. Some people like to drink salty pulp. Pour some soy sauce or add some salt into the soybean milk, and soon, the glistening tofu brain will appear in the bowl. There is salt in soy sauce, and the properties of salt and brine are similar, which can also destroy the colloidal state of soy milk and solidify protein. Isn't this the same as making tofu? Soymilk is brine, and tofu brain appears. Tofu brain filters out water and becomes tofu. Press the tofu tightly, and then squeeze out some water to become dried tofu. It turns out that soybean milk, bean curd brain, dried bean curd and dried bean curd are all protein beans, but they contain more or less water.
Milk is similar to soybean milk and is also a colloidal solution. In fresh milk, casein, that is, protein, is wrapped in cream, dispersed in water and constantly moving. Therefore, milk is always a uniform milky white liquid. Let the milk ferment into yogurt, and casein will gather and condense into a lump, like tofu brain.
Nowadays, tofu and its products are not only common food for China people, but also have gone abroad and enjoyed a world-renowned reputation. While fried chicken and steaks in the United States attract residents from other countries, tofu, a traditional food from China, has entered the American market with its unique charm, and has become a recognized ideal food with its outstanding advantages of high protein, low fat, low calorie and low cholesterol, which is favored by Americans.