My hometown uses salt water to make tofu. How does it order tofu? What exactly is salt water?

China's ancestors actually found a way to make tofu, which is one of the most amazing discoveries in history. As the saying goes, "everything has its vanquisher." Otherwise, I can only drink soy milk now. How does this brine turn soybean milk into tofu and then concentrate it into tofu?

What the hell is salt water? How does it turn soybean milk into tofu?

Generally, brine is easy to be misunderstood, because many people also call it brine, which is made of various edible spices. This article will not discuss it. The real brine is brine, which is a brine block formed by crystallization of the remaining mother liquor in the salt pond after salt is made from seawater or salt lake water. The main components are magnesium chloride, sodium chloride, potassium chloride, calcium chloride, magnesium sulfate and magnesium bromide.

Halogen block

Bittern blocks are also salty. Eating a small amount of them in tofu can supplement trace elements, but it must not be taken in excess, which will lead to poisoning, strong stimulation to skin and mucosa and inhibition to central nervous system. If people take it by mistake, they will have symptoms such as nausea and vomiting, dry mouth, abdominal distension, diarrhea, dizziness and headache.

How does brine order tofu?

After grinding the soybeans, wash them with clear water, dissolve the protein, and then boil them in water. Of course it can't boil, but it will bubble slightly! After skimming the foam floating on the surface, the remaining cauldron is almost a mixture of protein and water! At this time, the soybean protein particles are surrounded by water and keep moving, and they can't get together, forming a "colloid"!

The surface of soybean protein contains free carboxyl and amino groups. The action of these groups on water makes the surface of protein particles and the water film with the same charge form a gelatinous substance, and the repulsion between them makes the particles isolated from each other and will not stick together!

Brine is mainly magnesium chloride (MgCl2). These solutions belong to electrolyte solutions, and many charged particles (positive ions and negative ions) will be formed in water. The hydration of these ions captured the water film in protein, thus separating protein. In addition, the positive and negative ions of magnesium chloride electrolyte inhibit the repulsion generated by the surface charge of protein, which makes the particles agglomerate with each other, thus becoming a lump of bean curd!

Of course, it takes some time, and the waiting time at this time is called squatting, also called swelling or raising. It takes time to form a uniform and orderly three-dimensional structure between protein's peptide chains and between peptide chains and water molecules, so it is not appropriate to stir and vibrate at this time, otherwise the tofu rate will be low or the tofu will not be formed.

Concentrate into a ball

Of course, the function of brine can only form tofu, and the next tofu needs further operations, that is, squeezing, filtering out the water, and then pressing with gauze to squeeze out the excess water to form tofu!

Brine tofu is only a process of colloid aggregation, not a chemical reaction.

Dao Ji tofu gourmet

Besides brine, what else can turn soybean milk into tofu?

The tofu we usually eat includes old tofu and tender tofu. Radish and vegetables have their own tastes. The old tofu uses brine, and the tender tofu is gypsum. From the above, we know that other substances can also be used as "catalysts" for tofu as long as they meet the conditions for protein to solidify!

What meets this requirement can be gypsum, which is calcium sulfate! And gluconic acid-δ-lactone, which is called lactone tofu! Even white vinegar is ok, and some friends can order lemon juice tofu, so many friends who like pure nature use lemon juice to make tofu! There are also tutorials online, and interested friends can learn about them!

Of course, the principle of changing PH value is slightly different, but after adding acid, protein colloidal particles will approach the isoelectric point (soybean protein is glycinin, β-conglycinin, and the isoelectric point is about PH5). The net charge number of colloidal particles decreases, and the smaller the repulsion, the easier it is to reunite, but the result is the same.

Further reading: yuba (bean curd skin)

Bean curd skin is made by not boiling soybean milk, then cooling soybean protein and crusting on the surface. The making process is much simpler than tofu. Experienced friends will pull a few pieces of bean skin before making tofu. Of course, bean skin will increase and the output of tofu will decrease. But one operation can try two kinds of delicious food, which is very worthwhile!

What is picked up by the pot is bean skin, which can be picked up with chopsticks.

Bean skin is the material for making spring rolls, or soup, or meat skin rolls, all of which are essential raw materials! You may not have the courage to try making tofu, but the bean skin is too simple. Next time you cook soybean milk, put it in a big pot, prepare some chopsticks or specially get some long clean bamboo, and then find a place to dry!

Finally, the sodium chloride solution is also an electrolyte solution. You can also order tofu, but the amount is very large, and the tofu made is salty to death!