Glass jar of dill pickles in cloudy brine with garlic

Are Pickles Fermented? What the Evidence Says

ByCraig Brockie Last updated

The verdict: some pickles are fermented, but many are not

Pickles can be fermented, but many are not. A fermented pickle sours slowly in salt brine as bacteria turn the cucumber’s sugars into lactic acid. A quick or fresh-pack pickle gets its sour taste from vinegar and is usually heated. Even fermented pickles lose their live bacteria if they are pasteurized after fermentation.

So the answer to “are pickles fermented” depends on the jar. The label, the ingredient list and where the jar sits in the store tell you most of what you need to know.

What the research shows

There are two basic ways to make a pickle

University of Nebraska-Lincoln Extension describes two main types of pickles. Fermented or brined pickles are cucumbers held in a 2 to 3 percent saltwater solution for several weeks while bacteria on the vegetables produce lactic acid. Fresh-pack or quick pickles skip fermentation and use vinegar to lower the pH, and are usually made and processed within a day.

Ohio State University Extension makes the same distinction: quick-process pickles use acetic acid from vinegar rather than lactic acid from fermentation. Penn State Extension adds that fermentation acid has a more complex flavor than vinegar, which is why fermented pickles taste tangy and slightly funky rather than sharp.

How store-bought pickles are made

An EPA industry document on food processing lists three methods used to make commercial cucumber pickles: brine stock, fresh pack and refrigerated.

  • Brine stock: cucumbers ferment in salt brine, then are washed to remove excess salt before they are finished and packed. Pasteurization is optional.
  • Fresh pack: cucumbers are packed with salt, spices and vinegar, then heated until the center reaches about 165°F (74°C).
  • Refrigerated: cucumbers are not heat-processed before or after packing and rely on preservatives and cold storage.

This means a shelf-stable dill pickle may have started as a fermented cucumber and still be fermented in the technical sense. USDA researchers note that commercial bulk fermentation of cucumbers relies on natural microbes and brines of about 1 M sodium chloride. What happens after fermentation, such as desalting, adding vinegar and heating, decides whether anything is still alive in the jar.

Fermented does not always mean live

An expert panel from the International Scientific Association for Probiotics and Prebiotics set out a consensus definition of fermented foods in 2021. Its classification puts non-heated fermented vegetables among foods that contain live microbes, heat-treated or pasteurized fermented vegetables among fermented foods without live microbes, and vegetables pickled in brine or vinegar without fermentation among foods that are not fermented at all.

Pickle typeFermented?Live microbes likely?
Fermented, refrigerated, unpasteurizedYesYes
Fermented, then pasteurized (shelf-stable)YesNo
Fresh-pack vinegar pickle, heatedNoNo
Refrigerator vinegar pickle, not heatedNoNot from fermentation

Pickles as a source of live bacteria

Research on pickles as probiotic carriers is still early. In a USDA lab study, one acid-tolerant probiotic strain (a Lactobacillus casei) survived up to 63 days at 4°C in a simulated refrigerated pickle at about 100 million CFU per mL. That was a lab model meant to guide product development, not a test of pickles on store shelves or in people.

For gut health more broadly, the strongest human data come from varied fermented foods rather than pickles alone. In a 17-week Stanford trial of 36 healthy adults, a diet high in fermented foods increased gut microbiome diversity and lowered several inflammatory markers. Fermented vegetables were part of that diet, but pickles were not studied on their own.

Caveats to keep in mind

How to choose or make fermented pickles

Ceramic crock of cucumbers fermenting with dill and garlic

At the store

  • Look in the refrigerated case. Live fermented pickles need cold storage, so they are rarely on the center aisles.
  • Read the ingredient list. Cucumbers, water, salt, garlic and spices with no vinegar is a strong sign of a true lacto-fermented pickle.
  • Check the wording. Phrases like “naturally fermented,” “unpasteurized” or “live cultures” help. “Pasteurized” means any live bacteria are gone.
  • Expect cloudy brine. Cloudiness and a little sediment are normal in fermented pickles.

At home

The National Center for Home Food Preservation dill pickle recipe calls for fermenting at 70 to 75°F for about 3 to 4 weeks, or 5 to 6 weeks at 55 to 65°F. Avoid temperatures above 80°F, which make pickles too soft. Fully fermented pickles keep in the refrigerator for about 4 to 6 months if kept free of scum and mold.

Use the tested recipe exactly, check the crock several times a week and skim off any surface scum. If you already ferment vegetables, the same habits apply to sauerkraut and other brined vegetables.

Are dill pickles fermented?

Some are. Refrigerated dill pickles made with only salt brine are usually fermented, while most shelf-stable dills are vinegar-based or pasteurized after fermentation (EPA).

Do pickles have probiotics?

Only unpasteurized fermented pickles are likely to contain live bacteria, and their strains and counts are rarely known. Vinegar and pasteurized pickles are not a source of live cultures.

Are refrigerator pickles fermented?

Not usually. Most refrigerator pickles are quick pickles made with vinegar and kept cold, though some refrigerated brands are fermented in salt brine.

How long does it take to ferment pickles at home?

About 3 to 4 weeks at 70 to 75°F, or 5 to 6 weeks at 55 to 65°F (NCHFP).

Is pickle juice fermented?

Only if it came from a fermented, unpasteurized jar. Brine from a vinegar pickle is seasoned vinegar and salt, not a fermented drink.

Related topics

Sources

Craig Brockie is the founder of Ultimate Health Solutions, the company behind Ultimate Gut, and the author of Ultimate Health, The Ultimate Gut Health Guide and The Unlimited Probiotics Guide. After injuries and chronic health problems in his twenties that conventional care didn’t resolve, he began researching health on his own and has studied natural health for 30 years. He is not a medical professional, and his articles are general information, not medical advice.

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