The peculiar flavor, coupled with frequent scandals in recent years, many people ask again: What kind of food is this stinky tofu? Is it safe to eat?
First, stinky tofu is a fermented food.
In different areas, stinky tofu is made, processed and eaten in different ways, which can be roughly divided into two categories:
1, stinky tofu milk
That is, the canned stinky tofu milk that can be bought in supermarkets.
It is made from tofu by natural fermentation to grow mold, and then pickled with salt and spices.
This stinky tofu is blue, and it is said that it is famous all over the world because it is loved by Empress Dowager Cixi and given the name "Yu Qing Fang". It is also eaten in the same way as ordinary bean curd, for example, it is used to coat steamed bread and pie, or as a snack with porridge.
2. Stinky tofu
Stinky tofu in the south is often not eaten directly, but used as ingredients for further cooking, such as frying, charcoal roasting, steaming and so on. This kind of stinky tofu is easier to make than stinky tofu milk, just soak the tofu in stinky brine.
The fried stinky tofu often seen in snack street is made of this type of stinky tofu.
Either way, the core is that tofu is fermented. Bean curd is naturally fermented, mainly with mold; Dried tofu is fermented with stinky brine, and the strains are more complicated.
Second, why "smells bad and tastes good"?
"Smells bad and tastes good" is the unique feature of stinky tofu. This is not the exaggeration of fans, but has a sufficient scientific basis.
Smell and taste are two different sensory experiences.
Smell is a process in which volatile small molecules enter through the nasal cavity and are perceived by olfactory cells. "Taste" is a comprehensive experience that food is perceived by taste bud cells when it is chewed in the mouth, and at the same time, volatile molecules enter the nasal cavity from the mouth and are perceived by olfactory cells.
When we experience food, the molecules we "smell" and the molecules we "taste" are often different.
During the fermentation of stinky tofu, a part of protein of tofu is decomposed by complex microorganisms, and substances such as ammonia and sulfur-containing compounds are generated, which are the main sources of "smelly"-yes, such substances are also abundant in excreta. In addition, a large number of other kinds of volatile molecules such as ethers, alcohols and esters are generated in the fermentation process, which constitutes the unique smell of stinky tofu.
At the same time, protease produced by microorganisms will also hydrolyze protein into peptides and amino acids, and these fermented products have strong fragrance. The most typical one is glutamic acid-free glutamate is the effective component of monosodium glutamate and chicken essence, and all kinds of fermented bean products have a strong flavor, which is the mystery.
After cooking, especially frying and barbecue, on the one hand, those "odor molecules" are fully volatilized, and the odor is not strong; On the other hand, the umami flavor of amino acids such as glutamic acid is highlighted, and the Maillard reaction of amino acids at high temperature will further generate various flavor molecules, so it will taste delicious.
Third, "smelly brine" does have potential safety hazards.
In the production of stinky tofu, the key is the "stinky brine" used for soaking.
Different producers make stinky brine in different ways. Some of them leave rice straw and meat in the open air for several months and let them rot and ferment to obtain fermented liquid containing various microorganisms. Some people use Erythrina leaves, wild amaranth, bamboo shoots, Chinese flowering cabbage, wax gourd, ginger, pepper and other plants to ferment without meat, which also takes eight months or even longer to obtain qualified stinky brine.
These traditional ways of making stinky brine can't control the kinds of microorganisms in it. Although "friendly microorganisms" needed for fermentation can be obtained, pathogenic microorganisms harmful to health cannot be excluded. In addition, many small workshops use inferior raw materials and sewage to make stinky brine, and the hygiene is even more uncertain.
In contrast, modern production can monitor the quality of stinky brine to a certain extent, such as monitoring the number of pathogenic bacteria. The stinky tofu produced in this way is much safer.
Fourth, "manure" and "chemicals" stinky tofu is true?
On the Internet, you will see some reports about using "dung water" or "chemicals" to make stinky tofu.
From a technical point of view, it is impossible to make stinky tofu that smells bad and tastes good by using manure or chemicals alone.
However, it cannot be ruled out that the stinky tofu made by some unscrupulous vendors has some flavor defects, such as the stinky brine is not smelly enough or the color is not dark enough, so they try to "optimize" it by adding manure or chemical reagents. Or some unscrupulous traders just heard that someone was doing it and did it.
5. Can stinky tofu still be eaten?
As a kind of fermented bean products, stinky tofu produced in a standardized way is safe to eat. During fermentation, the metabolism of bacteria will also produce some vitamins, such as vitamin B 12, which is easily lacking by vegetarians, and its nutritional value is even higher than that of tofu.
It should be noted that stinky tofu, like other traditional foods, has no uniform flavor standard or production process-this diversity makes it difficult for people to objectively judge whether its flavor is good or not and whether it is qualified in safety and hygiene.
For diners who like to eat stinky tofu, buying products from large enterprises with clear sources and under the supervision of the government-their safety and hygiene will undoubtedly be much more reliable than roadside stalls with unknown sources.