Fermenting fruit is not difficult at all. Depending on the flavor or consistency you want to create or emphasize, there are different approaches. The most common ways to ferment fruit successfully and tasty, I share with you now. How fermentation works in general, and what the relevant characteristics of most fruits are, is also the foundation for the success of your ferment. If you don't feel confident about fermentation in general yet, it's best to read up again right away what I've put together for you.
Fruit ≠ Vegetables
Fruit contains significantly more sugar and wild yeasts than vegetables. Therefore, it ferments faster and also quickly turns into alcohol. Wild fermentation, the fermentation that happens because of naturally occurring yeasts and bacteria and works so well with vegetables, is of course also possible with fruit. Besides that, there are even more fun ways to make delicious and healthy fruit ferments yourself.
Tip 1: Increase salinity
What works very well is to increase the common salt content of 2% in the fermentation of fruit to at least 3-5% and additionally generate a brine by pressure. This means, for example, that you sprinkle ripe fruit pieces or berries with salt and weigh them down with weight(s). The salt and pressure will extract the liquid from the fruit and create a brine. It is important to note that the salinity should not reach more than 10%. In fact, fermentation takes place up to 10% salinity. If you use even more salt, you would start to talk about pickling. Also delicious, but not the subject here.
I like to use this type of fermentation to ferment plums. Fermented plums are the all-time classic and probably familiar to most fermentistas from Foundations of Flavor: The Noma Guide to Fermentation by René Redzepi and David Zilber. Quite simply, yet fabulously, I also enjoy small umeboshi-style apricots.
Tip 2: Combine fruit and vegetables
When fruit and vegetables are combined, a simple wild fermentation is possible. These combination ferments are as easy to produce as pure vegetable ferments and are among my declared favorites. The vegetables lower the total sugar content and thus slow down the fermentation process, as well as the formation of alcohol.
Great recipes for combining fruit with vegetables and incredibly delicious are all kinds of fruit fermented in the kkakdugi way, or fruit as a flavoring agent in a spicy sauce aka hot sauce. Fennel with blueberries is also one of my favorite ferments! You don't have to look far for the recipes, you can find them right here ↓.
Tip 3: Fruit fermentation using starter cultures
To direct the alcoholic fermentation more towards lactofermentation, the fruit ferment can be cultivated with the addition of a so-called starter. A starter culture consists of microorganisms capable of multiplying, for example sourdough, whey, water kefir, kombucha or koji.
Acidification right at the start of the fermentation process gives the lactobacteria a head start in the race for the available carbohydrates, leaving fewer for alcoholic fermentation. While the number of bacteria and yeasts are not affected by the addition of a lactic acid starter, the acid-producing bacteria are significantly increased. Due to the high acid production and lowering of pH, fermenting with starter cultures results in foods with low ethanol content and appealing sensorial quality. Therefore, lactic acid bacteria can be used as starter cultures to control fruit fermentation.
Tip 4: Fermenting with honey
Another absolutely delicious option is the fermentation of fruit with the use of honey. Berries, ginger, lemons, turmeric, oranges are good examples of fruit and honey ferments. You just have to make sure that there is not too much moisture from the fruit, otherwise you might accidentally make mead or a similar alcoholic liquid (like Katsulua, the delicious fermented coffee liqueur).
My favorite ferments with honey, with and without fruit, can be easily browsed on a dedicated page.
Teaser: Fruit vinegar
Homemade vinegar from fruits or fruit leftovers is great! It often tastes more intense than store-bought, is much cheaper and uses available resources - my apple cider vinegar made from skins and cores is a genuine zero-waste product.
Vinegar is a separate topic to which I am preparing an independent contribution. You can subscribe to this blog or to my instagram so that you will know about the publication. Or just drop by here again ☺️
Recipes for fermented fruit
Kanokwan Tandee, Chanida Nenthao, Chompunud Wongsakun & Junjira Wunchana. Lactic acid bacteria as starter cultures for fruit fermentation (2017). Conference: The 9th International Conference on Sciences, Technology and Innovation for Sustainable Well-Being (STISWB 2017), Kunming University of Sciences and Technology, China