In our hometown, several additives are usually added to the tofu. The first is of course brine, followed by plaster of paris powder, salty well water, sour grape skin water... In fact, many substances can coagulate tofu, because the protein of ground soy milk is in a free state, and when it encounters acid and alkali, All can form flocculent structures. At this time, it is gathered together and pressed to squeeze out the water, and it becomes tofu.

(The tofu cooked in salt brine is generally called northern tofu)

It is now generally believed that tofu was born during the Five Dynasties and Ten Kingdoms period. In fact, in one of my Qingyun articles, it was mentioned that tofu may have been born in the Xia Dynasty. At that time, there was no need for additives. It only needed to maintain a stable temperature for seven or eight hours, and the greasy proteins in the tofu could coagulate on their own. This kind of tofu is more delicate than lactone tofu and was only eaten by the uppermost aristocracy at that time.

(Brine produced by seawater sun salt)

Although this kind of tofu is delicious, it takes too long and the cost is too high. That’s why later generations had the habit of using salt brine to order tofu. In fact, this so-called salt brine has many sources. The source of salt brine at the seaside is often a by-product of drying sea salt. In southwest my country, brine is often brine produced from salt wells. When arriving in the northwest, salt brine is a natural extract from some saltwater lakes. After the Workers' and Peasants' Red Army arrived in northern Shaanxi, the special goods they talked about when doing business with the surrounding areas were not opium, but the high-quality salt produced in the local salt lakes. And this kind of table salt and salt brine are actually associated with each other.

Here is a brief introduction to the production process of sea salt brine. To put it simply, the seawater is first introduced into the pond, undergoes simple sedimentation, removes the seaweed, and then introduces it into the second pond. Through the evaporation of sea water, the crystallized salt produced is a brine. It includes magnesium carbonate, magnesium sulfate, sodium chloride and other substances. When used, it is dissolved in water to become brine.

(Jianshui Grilled Tofu)

In Jianshui, Yunnan, my country, the acid water produced in a local well can actually be called a kind of brine. The tofu cooked with it is excellent. It can be made into baked tofu, a local specialty snack. Although the making process of tofu is very simple, brine is rare and cannot be copied elsewhere.

(The tofu in the biological brine point has disappeared)

What is even more strange is that it is in Yiyang County, a county under Luoyang. A hundred years ago, an insect similar to stink bugs and beetles was abundant in the area. When the insect is purified by juicing, a pungent-smelling liquid is produced. Use it to make tofu, and it will turn golden in color and is called "oddly fragrant paste". Zhang Lanzhi, a famous gourmet in the Ming Dynasty, once mentioned that this kind of tofu is extremely delicious, with the fragrance floating in the sky, and the marrow of dragon, liver and phoenix. This kind of biological brine is unique in other places. Its production process began in the late Yuan Dynasty and ended after the insect resources were exhausted in the Qing Dynasty. I have tried to find this legendary delicacy, but to no avail.