Fermented pickles or brined pickles undergo a curing process for several weeks in which fermentative bacteria produce acids necessary for the preservation process. These bacteria also generate flavor compounds that are associated with fermented pickles. Initial fermentation may be followed by the addition of acid to produce such products as half dills or sweet gherkins.
Fermented pickles require sufficient acidity to prevent the growth of Clostridium botulinum (the bacteria that causes botulism) and possible toxin production. Refer to the food acidity and processing methods section of our canning basics series for a more detailed explanation.
The following safety tips are critical when preparing fermented pickle products:
- Don't alter the salt, produce, or water proportions in your recipe.
- Salt is a critical ingredient for fermented products. It helps to prevent undesirable bacteria from growing so desirable bacteria can produce lactic acid needed for preservation.
- Use only methods with tested proportions of ingredients that are recommended by USDA, Minnesota or other state extension resources, home canning equipment manufacturers, or other reputable sources.
- Ensure a uniform and adequate level of acid throughout the product using accurate measuring and thorough mixing of ingredients.
- Follow recommended temperatures, time, and weight usage during fermentation.
- Keeping the correct temperature during fermentation is critical to producing the needed acid and flavor compounds.
Watch our 5-minute home food fermentation presentation
Learn how fermentation preserves food and food safety practices to ferment a safe product.
- Select a variety of unwaxed cucumbers intended for pickling.
- Don't use immature table-type or "slicing" cucumbers.
- Use 1½-inch cucumbers for gherkins; 4-inch cucumbers for dills.
- Don't use produce that contains mold. Proper processing will destroy the organism but not the off-flavors which may have been produced.
Additional herbs and vegetables used should be fresh and of good quality.
For optimum quality, ferment the cucumbers within 24 hours after picking. If you can't do this, at least refrigerate or spread out the produce where it will be well ventilated and remain cool.
- Wash the cucumbers thoroughly, especially around the stem area to remove soil containing bacteria.
- Don't scrub cucumbers. Scrubbing removes the lactobacillus bacteria organisms needed to start the fermentation process.
- Remove the blossom end to prevent softening by enzymes.
- Use clean, fresh, insect-free heads of dill.
- Avoid over mature, dry, brown dill.
- Frozen dill may be used if stored in airtight containers, but flavor loss or change may occur.
- Use canning salt which does not contain any iodine and anti-caking agents that sometimes cause darkening and cloudiness in pickles. Again, this is a critical ingredient for fermented products because it inhibits the growth of undesirable bacteria.
- Don't use less salt or more water than the recipe requires.
- Use soft water if possible.
- Extremely hard water can cause discoloration of pickles, particularly if it has a high iron content.
- Some types of hard water may be somewhat softened by the following method:
- Boil water for 15 minutes.
- Skim off the scum and let the water rest 24 hours.
- When the sediment has settled to the bottom, pour off the water from the top and use.
- Use fresh spices for the best flavor in pickle products.
- Store leftover spices in airtight containers and in a cool place.
Alum may be safely used to firm fermented pickles, but it isn't necessary.
The calcium in lime also improves pickle firmness. Food-grade lime may be used as a lime-water solution for soaking fresh cucumbers 12 to 24 hours before pickling them. However, excess lime neutralizes or removes acidity and so must be washed out to make safe pickles.
To washout the solution:
- Drain the lime-water solution, rinse and then re-soak the cucumbers in fresh water for 1 hour.
- Repeat the rinsing and soaking steps two more times.
Equipment for fermentation
For measuring ingredients you'll need measuring cups, a spoon, and a kitchen scale if ingredients are specified by weight.
Suitable containers, covers and weights
- A clean 1-gallon container is needed for every 5 pounds of fresh vegetables. A 5-gallon stone crock is an ideal size for fermenting about 25 pounds of fresh cucumbers.
- Food-grade plastic and glass containers are excellent substitutes for stone crocks.
- Other 1- to 3-gallon non-food-grade plastic containers may be used if lined inside with a clean food-grade plastic bag.
Caution: Be certain that foods touch only food-grade plastics. Don't use garbage bags or trash liners.
Pack containers with product
Pack container, removing any air pockets, to about 75% full or 4-5 inches from the container rim. A fully packed container causes the brine to overflow and inhibits the fermentation process. Less than 75% full allows too much oxygen.
- Keep out oxygen by creating an anaerobic environment. This is done by keeping the cucumbers at least 1 to 2 inches under the brine to prevent undesirable bacteria and yeast that shows up as surface scum.
- To keep the cucumbers under the brine:
- Insert a suitably sized dinner plate or glass pie plate inside the fermentation container.
- To keep the plate under the brine, place 2 to 3 sealed quart jars filled with water on the plate.
- Or, use a plate weighted down with a very large, clean, plastic bag filled with 3 quarts of water containing 4½ tablespoons of salt. The bag should be properly sealed.
Storing the container during fermentation
Cover the container with a clean dark towel or coffee filter secured with a rubber band. This keeps insects and airborne molds out while allowing gases to escape that develop during fermentation.
Keep the container in a dark place or cover the container with a dark towel. Exposure to light will kill the bacteria needed to ferment your product.
Temperature and time are critical components of the fermentation process. Maintain required incubation temperature and timeframe.
- Store where the temperature is between 70 and 75 F for about 3 to 4 weeks while fermenting. Temperatures of 55 to 65 F are acceptable, but the fermentation will take 5 to 6 weeks. Avoid temperatures above 80 F, or pickles will become too soft during fermentation. Fermenting pickles cure slowly.
Monitoring product during fermentation
- Check the brine level every few days during the first week.
- If the brine level falls below the level of the product during the first week, dilute 1 tablespoon of salt in 2 cups of water and pour some of this brine over the product until it just covers the mixture. Weigh it down and cover.
- Don't worry if the brine drops after 7 to 10 days, by then you have created a safe environment and don't need to add more brine.
- The mixture will get bubbly and the brine will rise and seep out during the first week.
- After a day or two, if the covering is bulging or you don't see brine seeping out, carefully loosen the lid just until you hear gases escaping or see liquid seeping.
- Check it every few days to release the pressure from the gases that build up. Dispose of floating pieces.
- If sealed properly or using an airlock system, you don't have to skim the fine white film powder that forms on the surface. It's yeast and not harmful. The process works best when undistributed.
- If the film is above the ferment—over the weight used—oxidized yeast will form vinegar and increase the risk of mold growth. Skim this off.
Color and odor
- Browning, yeasty odor, slime or mold are signs your container is not airtight. Discard and start over, as spores can exist in the product.
- A cloudy brine or white sediment means the vegetables are fermenting well.
Storage of fermented products
Fermentation is complete when bubbling stops. Fully fermented pickles may be stored in their original containers for about 4 to 9 months, provided they are refrigerated and surface scum and molds are removed regularly. Keep submerged under the brine.
Canning fully fermented pickles is a better way to store them. To can them:
- Pour the brine from the crock or container used to ferment the cucumber into a pan.
- Heat slowly to a boil and simmer for 5 minutes.
- Filter brine through paper coffee filters to reduce cloudiness, if desired.
- Fill the jar with pickles and hot brine, leaving a ½-inch headspace.
- Place canning lid and screw band on jar.
- Process in a boiling water canner for the maximum Minnesota altitude (2,000 feet). If your location altitude is below 1,000 feet, you may deduct 5 minutes from the recommended processing time.
- Pints: 15 minutes.
- Quarts: 20 minutes.
The National Center for Home Food Preservation has a tested recipe for preparing and canning fermented pickles.
- USDA Complete Guide to Home Canning. Guide 6 Preparing and Canning Fermented Foods and Pickled Vegetables. 2015. https://nchfp.uga.edu/publications/usda/GUIDE06_HomeCan_rev0715.pdf
- Preparing and Canning Fermented Foods- Dill Pickles. National Center for Home Food Preservation. https://nchfp.uga.edu/how/can_06/dill_pickles.html
- Making Fermented Dill Pickles. Ohio State University Extension. https://ohioline.osu.edu/factsheet/HYG-5342
Reviewed in 2021