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 the 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.
For optimum quality, ferment cucumbers within 24 hours after picking. If this is not possible, refrigerate or spread out the produce where it will be well ventilated and remain cool.
- Use clean, fresh, insect-free heads of dill.
- Avoid old, dry, brown dill.
- Frozen dill may be used if stored in airtight containers, but you may notice a loss or change in flavor.
- This is a critical ingredient for fermented products because it inhibits the growth of undesirable bacteria.
- Use canning salt which does not contain any iodine and anti-caking agents that sometimes cause darkening and cloudiness in pickles.
- Don't use less salt or more water than the recipe requires.
- Hard water may interfere with the formation of acid and prevent pickles from properly curing. To soften hard water:
- Boil water for 15 minutes and let sit for 24 hours, covered.
- Remove any scum that is formed.
- When the sediment has settled, pour off the water from the top slowly to avoid disturbing the sediment at the bottom.
- Use fresh spices for the best flavor in pickle products.
- Store leftover spices in airtight containers and in a cool place.
- Use 5% acidity (50-grain) bottled vinegar.
- Do not use homemade vinegar or vinegar of unknown acidity in pickling.
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 wash out 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
Note on utensils and scales:
- Fermentation utensils must be washed in hot soapy water and rinsed well with very hot water before use.
- When heating pickling liquids, use unchipped enamelware, stainless steel, aluminum, or glass utensils. Other metals may cause undesirable color changes in the pickles or form undesirable compounds.
- 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 or plastic buckets intended for non-food purposes.
Covers and weights
- Cucumbers must be kept 1 to 2 inches under brine while fermenting.
- Insert a dinner plate or glass pie plate inside the fermentation container. The plate must be slightly smaller than the container opening, yet large enough to cover most of the cucumbers.
- To keep the plate under the brine, weigh it down with 2 to 3 sealed quart jars filled with water. The plate can also be weighted down with a large food-grade plastic bag filled with 3 quarts of water containing 4½ tablespoons of salt. Be sure to seal the plastic bag. Freezer bags sold for packaging turkeys are suitable for use with the 5-gallon containers.
- Covering the container opening with a clean, heavy bath towel helps prevent contamination from insects and molds.
The National Center for Home Food Preservation has a tested recipe for preparing and canning fermented pickles.
Recipes for other cucumber pickles
Refer to the USDA guide to Home Canning for recipes for:
- Bread-and-butter pickles
- Quick fresh-pack dill pickles
- 14-day sweet pickles
- Quick sweet 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 2022