Short answer
Pickling is a way of making and preserving food in an acidic environment, commonly by adding vinegar or by fermenting vegetables until microbes produce acid. Fermenting is the broader microbial process that transforms sugars and other food components. Some pickles are fermented; quick vinegar pickles usually are not. 1 2
Some pickles are made by fermentation, but fermentation also produces many foods that are not pickles. Added-acid pickles need not ferment.
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At a glance
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| Question | pickling | fermenting |
|---|---|---|
| Core process | Food kept in an acidic preparation | Microbes transform food components |
| Microbes required? | Not always | Yes |
What each thing is
Pickling. Pickling preserves or flavors food by creating an acidic environment. US usage includes direct-acid methods, often using vinegar, and fermented pickles whose acidity develops through microbes. 2
Fermenting. Fermentation is microbial transformation of food components. In fermented vegetable pickles, microbes convert sugars to acids, but fermentation is broader than acid production or food preservation. 1
Key differences
The distinction is between the acidic preserved food and the biological process that can create it. Adding vinegar can pickle vegetables without fermentation; bacteria can also ferment vegetables and acidify them. Fermentation extends beyond pickles, while pickling need not involve live microbes. 1 2
How to tell them apart
You can often identify pickled foods by reading ingredient lists: if vinegar or lemon juice is prominent, it’s pickled by added acid. If the label mentions fermentation or live cultures, it’s fermented. However, some products are both. 1 2
Where they overlap
Some foods, such as traditional dill pickles and sauerkraut, are both pickled and fermented. In these cases, microbes generate acid during fermentation, which pickles the food. Other pickles are made only with added acid and no fermentation. 1 2
Edge cases
Quick-process or fresh-pack pickles are not fermented; they are acidified rapidly with vinegar. Conversely, some fermented pickles may be finished with added vinegar for flavor or preservation, blurring the line between the two processes. 1 2
Why the distinction exists
Preservation guidance distinguishes added-acid methods from microbial fermentation because they produce acidity in different ways and require different tested procedures. In fermented vegetable pickles, microbes generate acid during the process. The same finished food can therefore belong to both categories, while a vinegar pickle may involve only pickling. 1 2
Common misconceptions
A common misconception is that all pickles are fermented. In fact, many US pickles are made by adding vinegar without any fermentation. Only some pickled foods, like traditional sauerkraut, are produced through fermentation. 1 2
Examples
At a US grocery store, you might find jars labeled ‘refrigerator pickles’ (made with vinegar, not fermented) next to ‘fermented sauerkraut’ (no vinegar added, microbes create acid). Both are pickled, but only one is fermented. 1 2
Sources
Sources checked October 3, 2026.
- National Center for Home Food Preservation — General information on fermenting. Microbial acid production and fermented pickles.
- National Center for Home Food Preservation — General information on pickling. Vinegar pickles and fermented pickles.