How come “big fat meat” and “little maggots” grow in vinegar?

Vinegar, as a common condiment, is often used in seasoning stir-fried dishes, cold dishes, dipping dishes and other dishes. It is a must-have in almost every household.

I wonder if you have ever carefully observed the vinegar in your home to see if there are any "big fat meat" or "little tadpoles"?

1

A piece of "fat meat" suddenly appeared in the vinegar bottle

In the vinegar jar for brewing vinegar or in the vinegar bottle that has been stored for a long time, you may occasionally see a layer of white, fat-like lumps inside, which feels like a sticky and elastic gelatinous substance.

The picture is from Xiaohongshu @小食光光

Of course, it is not fat, they are called vinegar moths or vinegar treasures.

Vinegar moth in vinegar bottle Source: Wikipedia

2

What is a vinegar moth?

Vinegar moths are actually a biofilm formed by the accumulation of acetic acid bacteria and their metabolites. If vinegar is placed in an environment of 4-7℃, vinegar moths will slowly accumulate thicker and thicker over time.

Seeing this, everyone will definitely think: If we don’t use acetic acid bacteria in vinegar, can’t we avoid vinegar moths in vinegar?

In fact, vinegar with vinegar moths can ensure that it is 100% brewed vinegar! Because only brewed vinegar uses acetic acid bacteria.

According to the production process of vinegar, it is divided into two categories: brewed vinegar and blended vinegar. Brewing vinegar is the process of fermenting raw materials such as sorghum into acetic acid by acetic acid bacteria (Acetobacter); while blended vinegar is diluted with edible glacial acetic acid and does not contain any acetic acid bacteria at all.

In Europe and the United States, many vinegar bottles are specially marked with "mother of vinegar" to prove that the vinegar is brewed vinegar. Therefore, they are also called vinegar mother by foreigners (it does not mean that there is my mother in the vinegar).

Apple cider vinegar from the United States Source: Wikipedia

3

Are vinegar moths poisonous?

In the vinegar brewing process, vinegar moths can be said to be a "double-edged sword". On the one hand, acetic acid bacteria fully decompose nutrients such as glucose and fructose in the vinegar tank and aggregate into a biofilm. Vinegar moths can effectively inhibit the growth of other bacteria and produce by-products such as gluconic acid, which improves the flavor of vinegar. On the other hand, vinegar moths and sugars cannot coexist. The more vinegar moths are produced, the more sugars are consumed, which will reduce the production of acetic acid.

Therefore, in order to ensure food safety during the modern industrial production of vinegar, manufacturers often pasteurize the vinegar before it leaves the factory to kill all bacteria, including acetic acid bacteria.

The finished vinegar we can see now is generally brewed by folk workshops or home-brewed vinegar.

However, for the food industry, the bacterial film produced by acetic acid bacteria is harmless and has been incorporated into recipes and widely used. For example, the coconut fruit in milk tea is a bacterial cellulose film formed by the fermentation of coconut milk by wood acetic acid bacteria (a type of acetic acid bacteria).

Coconut

4

In addition to growing meat, can tadpoles also grow in a vinegar bottle?

Have you ever seen the "tadpoles" in rice vinegar? If you see regular waves on the surface of the rice vinegar at home, you are looking at the white "tadpoles" I mentioned. Its name is vinegar eel (Turbatrix aceti).

For us humans, vinegar is just a condiment, but for them, vinegar is the environment they depend on for survival. They are not only not afraid of acid but are also particularly resistant to acid.

5

What is vinegar eel?

Vinegar eel is a type of invertebrate belonging to the phylum Nematoda. Their body is linear, with a head and body that are generally thick, a thin and narrow tail, and a body length of about 1 mm. Because its appearance from the side is similar to that of an eel, it is named vinegar eel, also known as vinegar nematode.

They feed on Acetobacter in vinegar, are hermaphrodites (i.e. have both male and female reproductive organs), and reproduce very quickly.

Newly born vinegar eels are extremely small and difficult to observe with the naked eye. When small waves can be seen with the naked eye, it means that there are already many vinegar eels in the vinegar bottle.

Moreover, some scholars have found that vinegar eels can move rhythmically and in coordination when they gather together.

Top: Vinegar eels under a microscope (Source: Wikipedia), Bottom: Coordinated movement of vinegar eels, Source: See watermark

6

Can vinegar eels be eaten? Can vinegar from vinegar eels still be consumed?

Nematodes are extremely widely distributed. Some parasitize humans, animals, and plants, and some live in soil or water. Currently, 35 species of nematodes have been found to parasitize humans and can cause disease, such as roundworms, hookworms, whipworms, etc.

Vinegar eels live in vinegar and have a strong adaptability. They can survive in pH values ​​of 1.6-11, as well as high and low temperatures. Henry Power from the UK once froze vinegar eels outdoors in the cold winter. After thawing, the eels were still alive. To kill them, a temperature of more than 44°C is required.

Foreign scholars (G. Lohde) have found that another kind of "worm" parasitizes in the body of vinegar eels, namely harposporium anguillulae.

Currently, no research has found that vinegar eels can cause disease, but further research is needed to determine whether vinegar eels can cause disease.

Although the vinegar eel moving in the vinegar bottle may cause discomfort to people with trypophobia, it is an excellent fish bait, especially for newborn fish, and you can eat them one by one without any pressure.

7

How to avoid vinegar bugs

How did the vinegar eel get into the vinegar bottle?

In fact, vinegar eels are spread by fruit flies. There are two transmission routes. The first is direct transmission on the raw materials for making vinegar. For example, apples are in close contact with fruit flies before making vinegar, so they are likely to carry vinegar eels. The second is that fruit flies fly into the brewing area and directly bring the vinegar eels into the vinegar being brewed.

However, the vinegar we eat is generally pasteurized before leaving the factory, which can kill all vinegar eels. If you find vinegar eels in an unopened vinegar bottle, you can contact the seller or manufacturer in time. It is also okay to feed the fish directly.

What we need to pay attention to is that after opening a bottle of new vinegar at home, you must remember to cover the lid in time!

END

Tadpole Musical Notation original article, please indicate the source when reprinting

Editor/Xiao Xitushuo