What is the mother in apple cider vinegar?

The "mother" is a cloudy, jelly-like film of cellulose made by the harmless acetic acid bacteria that turn alcohol into vinegar. It can form naturally in vinegar, which is why some bottles look cloudy. Most producers pasteurise vinegar to stop it forming. Vinegar with a mother is not spoiled, and you can filter it out.

Updated 2026-10-02

Key facts

What it is. The mother "is actually cellulose ... produced by the harmless vinegar bacteria". [1]
Where it comes from. It occurs naturally in vinegar as a result of the acetic acid bacteria. In 1837 Kützing described it as a thin film covering the surface of the liquid. [1] [2]
Pasteurisation. Most manufacturers pasteurise before bottling to stop a mother forming on the shelf. [1]
Not spoiled. It may start to form after opening; the vinegar is "not harmful or spoiled". [1]

Why do some vinegars say "with the mother"?

The phrase tells you the vinegar still contains some of this cloudy material. Check the label to see whether it has been pasteurised or filtered. The mother is a by-product of making vinegar, not an added ingredient; see how apple cider vinegar is made. [1]

How was the mother discovered?

In 1732 the Dutch scientist Boerhaave noted that the "mother of vinegar" was a living organism; in 1837 Kützing first looked at the surface film under a microscope. [2] Today, acetic acid bacteria are known to turn alcohol into acetic acid.

Related answers: how apple cider vinegar is made · what kombucha is

Related on Cider Radar

Guide: how cider is made, the first step on the way to cider vinegar
Glossary: fermentation

We don't give health advice. For questions about your health, talk to a doctor or pharmacist.

Questions

Is vinegar with a mother safe?

The Vinegar Institute says vinegar containing a mother is "not harmful or spoiled" and the substance can be filtered out. [1]

Is the mother the same as a kombucha SCOBY?

No. The vinegar mother is a film made by acetic acid bacteria; a kombucha SCOBY is a culture of yeast and bacteria used to ferment sweet tea. [1] [3]