Preserving vegetables with fermentation is a great way to eat fresh and local all year round!
When vegetable gardens and farmers’ markets are full in the summer and early fall, take advantage of this opportunity to stock up. Lacto-fermentation is an excellent way to preserve seasonal vegetables for several months.
This way, you will be able to enjoy the sunny taste of freshly picked vegetables, even in the middle of winter!
Simple lacto-fermentation is a good method of preservation (see our complete guide on making fermented vegetables).
However, fermented vegetables are living foods, and they change over time. Taste, colour and texture may evolve.
That said, there are many tricks to extend the life of your fermented vegetables so that they will keep their good taste and crunchiness for several months (or even years!).
Eating local and fresh all year round is possible, thanks to fermentation!
Why Does Fermentation Preserve Vegetables?
Lacto-fermentation is an ancient method of preserving vegetables in a safe and easy way. The secret? Lactic acid bacteria!
To preserve vegetables by fermentation, they are placed in an oxygen-free and salty environment.
This environment encourages the growth of lactic acid bacteria, which are bacteria that are good for humans.
These bacteria create lactic acid, which prevents bad microorganisms from developing. Fermented vegetables are therefore very safe to eat, even after many months or even years at room temperature!
And it’s thanks to this lactic acid that fermented vegetables develop that tangy taste that we love so much!
Contrary to canning where vitamins are destroyed by heat, lacto-fermentation preserves all the vegetables’ nutrients.
In addition, the work of good bacteria can even create new vitamins and make nutrients already present in vegetables more easily assimilable.
It is therefore a perfect technique to preserve – and improve! – your seasonal vegetables (see the 10 best vegetables to ferment to take advantage of the harvest season).
Keep in mind that the taste, texture and colour of vegetables change with fermentation.
A fermented vegetable is more acidic, softer and saltier than a raw vegetable. Just think of the difference between a cucumber and a pickle!
As a general rule, the longer the fermentation process is, the tangier and less crunchy the vegetable will become.
How to Extend Shelf Life of Fermented Vegetables?
Choose the Right Vegetables
All vegetables can be fermented, but their textures and tastes will change over time!
Choose fresh, firm vegetables. Vegetables that have just been picked will keep their texture longer and are full of vitamins and minerals.
Conversely, other vegetables such as leafy greens (lettuce, etc.), tomatoes or zucchini will gradually turn into mush as the months go by. This is not necessarily a bad thing, however. You may wish to make a sauce out of them, or add them to soup or salsa!
Increase the Amount of Salt
Salt plays an important role in lacto-fermentation: it prevents dangerous bacteria from spoiling your food.
In addition, it slows the speed of fermentation and helps keeping vegetables crisp longer.
The amount of salt in fermented vegetables can vary depending on the taste and texture desired. Most recipes recommend 2% of the total weight, i.e. 20g of salt for 1kg of vegetables.
To preserve the firmness longer, we recommend using between 2.5 and 3% of salt instead.
For more information, see How much salt for fermentations?
Lower the Temperature of the Fermentation
Cold temperature slows down the speed of fermentation. To preserve your vegetables for the long term, it’s better to keep them in a cool place. Here is our favourite technique:
- Put the vegetables in jars following our lacto-fermentation tips or the directions in your recipe.
- Allow to ferment at room temperature (18-20°C or 64-68F) for a few days or weeks (according to your taste).
- Keep in a cool place (12°C/53F and below) to slow down the fermentation.
Refrigeration (about 4°C or 39°F) is the easiest option to preserve your fermentations. It helps the vegetables to keep their aroma and texture.
Unfortunately, you can quickly run out of space in your refrigerator! Several other options exist to preserve your fermentation:
- Cold basement
- Vegetable cellar
- Cold room
- Wine cellar
- Cooler corner of the apartment
The optimum temperature for storage is below 12°C.
However, even if you keep your jars at 27°C, fermented vegetables will still be good and safe. They will simply be more acidic and softer. Your sauerkraut will be delicious in a soup, and your jalapeño sauce won’t suffer at all!
Preserving Your Fermented Vegetables
Once your jars have started fermenting, leave them alone!
Sometimes, some water will evaporate, leaving the tops of the vegetables uncovered. It is recommended not to touch them.
At this stage of fermentation, if the jar is closed well, the air in the neck of the jar will normally be replaced by CO2, creating an inhospitable environment mould.
However, if you are in the early days of fermentation, it is possible to open and push the vegetables under the brine, or even add brine.
When you open a jar, it is best to put it in the refrigerator and eat its contents in the following weeks.
Caution: with time, salt and humidity, some lids may rust. To avoid this, use plastic lids, which are more durable.
By choosing firm, fresh vegetables, adding more salt and keeping fermented vegetables cool, you can eat fresh, local vegetables all year round!