Fermenting Vegetables

What makes vegetables ferment instead of rot?

First of all, fermented vegetables ferment instead of rot because of the natural beneficial microbes in them. The job of the cook is to give those beneficial microbes the best possible environment to thrive and multiply. At the same time the environment needs to discourage the bad microbes that cause rot from multiplying and overpowering the mixture. This is where the salt comes in. Salt inhibits the growth of microbes.

Food that is naturally high in moisture like finely cut cabbage requires less salt than food with a hard rind, like lemons, in order to discourage the bad microbes. Food that spoils faster, like herrings, require more salt than food that is slower to spoil, like beets.  Salt also causes osmosis — a transfer of juices from the vegetables that is replaced by brine, further inhibiting spoilage.

Let’s look at what actually goes on as vegetables ferment

When you start to ferment vegetables (or dough or fish) there are hundreds of different microbes on the surface that are vying for supremacy. Whether you end up with rotting food, mold, or a nicely fermented food, depends on encouraging the good microbes, while trying to crowd out the bad microbes. The good microbes thrive in an acidic environment while the bad microbes don’t. Some microbes need air to multiply while the good microbes need an anaerobic environment.

You want to begin with more of the good microbes and less of the bad. Always wash your vegetables under cold, running water before you prepare them for fermented vegetables. This washes off some of the undesirable microbes right at the beginning. Wash and sanitize knives, cutting boards, jars, and bowls before you begin to make your ferment.

Salt inhibits the growth of yeast and delays the bad microbes from reproducing and this is why salt is commonly used in fermented vegetables. Use kosher salt or sea salt rather than table salt (Iodized salt) because the addition of iodine, an antimicrobial, will inhibit the good microbes, too and discolour your vegetables.

Inoculating a jar of fermenting vegetables with the good microbes will encourage the good microbes to reproduce at a faster rate, crowding out the bad microbes.  This replaces some of the need for salt in your recipe.  If your recipe calls for 2 tbsp of salt per quart — if you innoculate your vegetables with good microbes you can use 2 tsp of salt instead.

The 3 stages of fermenting vegetables

Timing	What you’ll see		What’s happening inside the jar
Day 1 to 2	Fine bubbles begin to form which break the surface when a knife is inserted inside the jar		Coliform bacteria begin the fermentation process. As it grows the mixture becomes more acidic.
Day 3 to 5		Large gaseous bubbles form inside the jar. The food is pushed up from the bottom against the weight.   Unweighted food is pushed above the brine. The jar liquid overflows through the airlock.	The Leuconostoc bacteria are multiplying and continue lowering the pH in the vat. This crowds out the coliform bacteria.
Day 5 to 8		The bubbling slows down or stops. The vegetables fall down in the jar and the pressure stops building up. The ferment can be refrigerated. It will continue to develop while in storage.	The environment in the jar has become more acidic and the lacto-bacteria is thriving, while the other bacterium and yeasts are being crowded out. The lacto-bacteria are living and active inside the ferment.   The fermentation can be slowed by refrigerating the ferment. It can be eaten now or the flavours can continue to develop over months. The jar contents are preserved in the acidic environment of the jar.

Adapted from http://joybileefarm.com

Image from http://www.amertha.com