The case is solved, and these two in the sour bamboo shoots are the "culprits"

Snail powder is a street snack that was born in Liuzhou, Guangxi in 1970s and 1980s. The soup made of snail and pig bones is delicious, and it is served with rice noodles famous in Yunnan and Guangxi, as well as seasonings such as fried peanuts, peppers, fungus and sour bamboo shoots, which makes this food sour, spicy, fragrant and fresh.

All well-known stinky tofu, bean juice, pickled puffins and other stinky tofu. It is only after fermentation that there is a symbolic inner taste. The only fermented ingredient in snail powder is sour bamboo shoots.

The production technology of sour bamboo shoots is relatively extensive. Choose bamboo shoots with appropriate size, soak them in salt water and leave them for ten days to produce sour taste. The fermentation environment of sour bamboo shoots is not completely isolated from oxygen. Through the synergistic effect of aerobic bacteria and anaerobic bacteria, the sugar and protein in bamboo shoots are fermented into various amino acids, organic acids, aldehydes, alcohols and other substances.

What makes sour bamboo shoots taste?

By consulting the literature, a clue appeared: a paper from Guangxi University mentioned that compared with fresh bamboo shoots, the cysteine content in sour bamboo shoots decreased significantly, while tryptophan was not detected at all. In other words, cysteine and tryptophan are converted into other substances during fermentation. Speaking of the metabolites of these two amino acids, a strong taste came to my face.

As a sulfur-containing amino acid, the metabolite of cysteine is "notorious" hydrogen sulfide, an odorous substance in fart. The classic description of hydrogen sulfide in chemistry books is "rotten egg-flavored gas", which shows how iconic its taste is. Most substances containing sulfhydryl (also called sulfhydryl, -SH) have this smell, so it is often added to colorless and odorless pipeline gas, and people can easily detect gas leakage.

The metabolite of tryptophan is more unique, and its name is dung odor. At low concentration, the smell of feces itself is not only tasteless, but also the source of many floral odors. Many perfumes and aromatherapy products also add dung odor as a flavoring agent. However, if the concentration is too high, the dung odor will soon become smelly, and as can be seen from the name, the smell of dung odor is the smell of dung. This story tells us that we must not spray too much perfume, which will stink.

Cysteine and tryptophan in sour bamboo shoots are consumed in large quantities, and the final products, hydrogen sulfide and fecal odor, accumulate, resulting in a strong internal flavor. Coupled with the spicy combination in the processing of snail powder, all kinds of odor substances are accelerated to volatilize, which makes people feel slightly drunk for three days after eating.

Smelly, smelly, easy to digest and absorb. Doesn't it smell good?

However, the rancid smell may be a scent of primitive humans in the early stage of evolution.

In nature, rancidity mostly comes from microbial fermentation. Food fermented by microorganisms will be easier to digest and absorb than the original food, because microorganisms have helped people "digest" in advance. For example, in the process of making sufu, protein in tofu is decomposed into small molecular amino acids by protease secreted by Mucor, which is more conducive to human absorption. In other words, in protein, the absorption and utilization rate of tofu milk is higher than that of eating tofu directly. Similarly, most other fermented foods also contain more amino acids. Fermentation is related to odorous substances, so odor is also a nutritional marker. People like to eat sour bamboo shoots, bean juice, moldy amaranth stalks, stinky tofu, stinky mandarin fish, canned herring and so on, probably because "eating stinky" has long been written in the genes of human ancestors.

The stinky fermented foods around the world are: canned herring, moldy amaranth stalks, bean juice, stinky tofu, pickled puffins, and natto.

At this point, the smell of snail powder in the room seems to be less unpleasant. What can I do if I indulge once? Let me join this long story!

The taste of snail powder is definitely not explained by one or two substances. In fact, the special flavor of each fermented food is composed of dozens or even hundreds of volatile substances. Hydrogen sulfide (or other sulfhydryl groups) and fecal odor can only explain the source of some odors (or feces-like odors). There are many alcohols, aldehydes and acids in snail powder, which contribute to its smell.

In addition to some stinky foods that we are familiar with, what's more, in Dongyang, Zhejiang, there is a special product "boy's egg", which is cooked with children's urine and is said to have nourishing effect. The main reason is that the child's renal function is not fully developed, and all nutrients cannot be reabsorbed into the blood when urine is formed, so some amino acids will be excreted with urine. These amino acids ... well, they are nutrients.

But in that case ... it seems that a bowl of soup is more tonic ... but this example can prove that under the condition that protein's absorption effect is not as good as amino acids, human beings really prefer some food sources that can directly contain amino acids.