What is fermentation?
All fresh produce naturally contains microorganisms like bacteria, yeasts and moulds. Some of these microorganisms will spoil your food, but certain bacteria are beneficial and under the right conditions can transform raw foods into something really special. The beneficial bacteria break down the natural sugars into forms that are easier to digest. Lactic acid is a by-product of fermentation which helps to control any harmful bacteria and preserves the vegetables.
This page will cover the basics and focus on sugar and starter fermenting methods. Salt fermenting (typically done with vegetables) has it's own page.
Fermenting vegetables usually uses salt to create a brine. When finished, the texture of the food is somewhere between fresh and pickled so it's softer than fresh but still usually somewhat crunchy. See our salt brining page for details!
Salt isn't the only way to ferment. Sugar also inhibits growth of harmful organisms so sugar, honey, or sweet fruits can be used as a base for fermentation. This is often used in alcohol production (which we don't explore on this site). Immersing produce like garlic in honey is an easy way to ferment.
Use freshly harvested vegetables. Scrub off soil and wash well in cool water. Start fermenting soon after harvesting your vegetables for best results. Do not use store packaged baby carrots or other "ready to eat" vegetables as they may have been treated with food-safe cleaners that will prevent successful fermentation.
Food grade plastic containers, glass or ceramics are good. Don’t use containers that have scratches or cracks which might harbour harmful bacteria. Metal containers (except for stainless steel) may react with the acid in the food and give it a strange flavour or colour. Never use plastic garbage bags or garbage cans for fermenting. Large ceramic crocks are good for fermenting larger amounts of food.
Wash all surfaces, tools and containers used for fermenting. Use hot sudsy water and then rinse well with very hot water.
Use freshly harvested fruit and vegetables. Scrub off soil and wash well in cool water. Start fermenting soon after harvest for best results.
After fermenting you can put the finished product in smaller clean containers and store them in a cool place like a refrigerator. When temperatures are cooler, fermentation slows down. That’s why fermented foods can be stored for up to three months or longer, without losing their quality and good taste.
If you want to store fermented foods much longer than 3 months, you may wish to can them using recommended processing times for each food. Canning will alter the beneficial organisms that live in your product so if you're very keen on the health benefits of these, you may wish to plan smaller, more frequent batches to ensure they get eaten. There are some fermenting methods that use "starters" from existing ferments where you'd frequently add new produce. This is a different method and does not require canning to maintain long term.
This page is new so we haven't added the sugar and starter fermentation recipes yet. We keep the salt brine recipes on the Fermenting vegetables with salts page. Expect to see more here come harvest time!
Sources and further reading
Since it is no longer a common food preservation technique, a lot of people are concerned about fermenting foods. It helps to see other people succeed with recipes you've never considered. There are many fantastic Facebook groups dedicated to fermenting. Join one and see what everyone is doing. The variety of fermented foods people eat may suprise you!
Hertzberg, Ruth; Greene, Janet; Vaughan, Beatrice (2010) Putting Food By: Fifth Edition. New York, New York: Penguin Group (USA) Inc.
Lewin, Alex (2012) Real Food Fermentation: Preserving whole fresh food with live cultures in your home kitchen. Beverly, Massachusetts: Quarry Books.
Cancler, Carole (2012) The Home Preserving Bible. New York, New York: Penguin Group (USA) Inc.