How is apple cider vinegar made?

Key facts

• Two processes. "Vinegar is always the result of the fermentation of sugars (from agricultural origin) into alcohol by yeast, and the fermentation of that alcohol into acetic acid by acetic acid bacteria." [1]
• US definition. Cider vinegar is made by "the alcoholic and subsequent acetous fermentations of the juice of apples". [2]
• Minimum strength. Retail vinegar in the US should be at least 4% acidity; cider vinegar is typically about 5–6%. [1]

What are the steps in making apple cider vinegar?

1. Press apples for juice.
2. Alcoholic fermentation. Yeast turns the sugar into alcohol. This is the same first step as cider making; see how cider is made. [1]
3. Acetic fermentation. Acetic acid bacteria, which need oxygen, turn the alcohol into acetic acid. [3]
4. Finish. The vinegar is filtered, often diluted to strength, and usually pasteurised. [2] [1]

What is the difference between traditional and industrial vinegar making?

• Surface culture (traditional). Bacteria grow at the surface of the liquid in partly filled barrels; the "Orleans method" is a standardised version. [3]
• Submerged culture (industrial). Air is pumped through the liquid in stainless-steel tanks; it is faster and cheaper but can lose more volatile aromas. [3]

How do you make apple cider vinegar at home?

Penn State Extension gives a home method: [4]

1. Make cider from autumn or winter apples: wash, crush and strain the juice. Adding wine yeast speeds fermentation but is not essential.
2. Fill containers to about three-quarters, in glass, plastic, wood, enamel or stainless steel, never other metal, and cover with cheesecloth instead of a lid.
3. Stir daily and keep the containers out of direct sunlight at 60–80°F (16–27°C); full fermentation takes about 3–4 weeks.
4. Filter through several layers of fine cheesecloth or a coffee filter, which removes the mother.
5. Pasteurise and store in sterilised, capped bottles.

Because the acidity of homemade vinegar varies, Penn State advises against using it in foods to be canned or stored at room temperature. [4] Retail vinegar in the US must be at least 4% acidity. [1]

Related answers: cider vinegar vs apple cider vinegar · what the mother 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.