This is one of the easier ferments that I’ve gotten familiar with. All you need is a clean container, some fruit, salt, and a bit of time. It’s a lactic acid fermentation, probably most familiar to people (certainly to me) through kimchi.
The team at Noma suggest letting the fermentation happen a bit warmer than room temperature, closer to 28 °C (82 °F). Unless you happen to keep your house very warm, that probably means using a dedicated fermentation chamber. I’m not quite at that point yet, so if you’re not ready to make that commitment, don’t worry. This will still work at room temperature, even if it will take a bit longer.
The formula lists out the ingredients — all two of them — for a kilo of fruit. Obviously, this is incredibly easy to scale up and down if you want or need a bit less output.
For anything other than very small fruit (e.g., blueberries, raspberries), I’d halve or quarter the pieces before starting the ferment.
I’ve had success using this technique with everything I’ve tried. I’ll also admit it can be a bit of an acquired taste. There isn’t really an easy way to provide a guide for when the ferment is ready. You have to taste it along the way to find something that works for what you’re trying to achieve.
And don’t toss the fermentation medium. The fermenting liquid makes an amazing addition to a cocktail or, after reduction, an incredible glaze for a piece of fish, or a vegetable like corn on the cob.
Empirically, the fermentation with all the fruit that I’ve tried has peaked at a pH around 2.5, so reasonably acidic.
The type of salt used also can have an impact on flavor and, potentially, fermentation speed. As I try more, I’ll attempt to update this page.
| Reagent | Composition | Characterization |
|---|---|---|
| Diamond Crystal kosher salt | ~100% NaCl | Aggressive, punchy, easy to taste distinct flavors |
| Sel gris de guérande | ~99% NaCl with traces of other minerals | Round, soft, and uniform flavors |
Ingredients
- 1 kg fresh fruit
- 20 g (2%) salt
Method
In a large vacuum bag, toss together the fruit with the salt, ensuring an even mix. Then vacuum seal the bag.
Leave the bag out at room temperature or just above (ca. 20-30 °C). Periodically burp the bag by cutting it open to release the built up gasses, and taste the fruit and fermentation medium. Close and re-vacuum seal the bag.
Over time the fruit should develop more acidity and a lightly alcoholic fizz when the process is working correctly.
When it doubt, if the products taste off, discard them.
When the fermentation has developed to taste, stop the fermentation by transferring to a refrigerator, where it will keep for 2-3 days. For longer term storage, freeze the fruit and liquid separately.