The Bacterial Succession Explained
The Bacterial Succession explained through anaerobic vegetable fermentation
A guide by Alexis Goertz – Edible Alchemy
YEAST: Yeasts eat sugar and creates bubbles! The vegetables we use to ferment have yeasts naturally occurring on their skin. These yeasts are looking to eat sugar all the time. The sugars that the yeasts love are contained in the vegetables. We can see yeasts on darker fruits and vegetables like purple grapes or red cabbage. The yeast often looks like white dust and is often mistaken for dirt, dust or pesticides. However, that is the magic naturally occurring ingredient to fermentation!
Some vegetables, fruits, roots and rhizomes have much more yeast on the skins, such as cabbage, or ginger, while some have less. We might end up peeling or scrubbing lots off in the cleaning process, such as beets, carrots and other root vegetables. In this case, root vegetables are successfully combined together with very yeasty vegetables in a ferment. Such as carrots with cabbage. Or beets with ginger (skin left on the ginger!) to ensure the best bacterial succession.
SUGAR: As mentioned above, sugar is contained in most of these vegetables and when yeast meets sugar in a moist environment, yeasts eat those sugars and fermentation begins. For vegetable fermentation, one does not need to add extra sugar to help the process as almost all the ingredients (just missing salt!) are already present unless a particular sweetness or taste is desired. One can add small pieces of more sugary fruits and vegetables such as apple, pear, red beet and tomatoes. Just remember, the most sugar in a ferment means more bubbles!
WATER: Water is often in the vegetables itself and with salt can be drawn out. However in cases of hard vegetables, water needs to be added to help aid the yeast meeting the sugar. Make sure if you are using tap-water, that there is no chlorine or fluoride in the water. Chlorine especially kills bacteria and we are working with bacteria here. If the tap water is chlorinated, let it sit in a bowl for 24 hours and the chlorine will evaporate. Or boil it for 3 minutes and let cool down to room temperature. Otherwise try using your local tap, spring or well water to get new tastes!
AIR: For almost all vegetable ferments we want ANAEROBIC (no air entering) environments. To achieve this, we need to keep our vegetables under the salty water (brine) that they are in. We can push the vegetables under the brine with a weight, with a plate and a rock on top, with a jar filled with water inside a jar, with the cabbage core or cabbage leaves. As the ferment begins (starts to bubble) the vegetables will try to push themselves out of the jar and into the air. If the vegetables touch the air, they will oxidize and not taste so good to us. It is rather composting than fermenting. So pushing those vegetables down after the bubbles start might be necessary – as well as adding extra water if some has leaked out.
Optional: consider using an ‘airlock’ device that sticks out of your ferment. It allows the built up air to escape but no outside air to come in. with an airlock we ensure the most anaerobic conditions and the best environment for the lactic acid to thrive without competitors from the outside air.
SALT: Salting our vegetables with good quality salt is important. Using iodized salt doesn't give us anything back in return. Iodized salt is stripped of all its mineral content whereas sea salt, mountain salt and other natural salts carry beneficial minerals in which we can incorporate into our foods and thus into our bodies.
Salt keeps things crunchy and crispy. It too is a form of food preservation. Salt helps us draw out the water inside vegetables which in turn pulls out the sugars from the inside which mix with the yeasts on the outside of the vegetables to create a desirable bacterial succession. Salt makes the environment amiable for the good lactic acid bacteria to live.
And most importantly, salt helps brighten tastes of our food and our ferments.
For optimal results, salt concentration is the first step in establishing a safe fermentation environment. The right salt concentration help creating a happy home for lactic acid producing bacteria (the good ones that we need and want!).
These bacteria are species are of the Leuconostoc and Lactobacillus.
Vine growing vegetables such as peppers, cucumbers, pumpkins, grape leaves tend to need 3%-4% salt concentration. Low growing vegetables, such as cabbage need 2.5%. Root vegetables tend to ferment best in the presence of other vegetables like cabbage and also a 2.5-3% salt concentration.
TEMPERATUR: We start by leaving the vegetable ferments at room temperature. 20-24 Celsius / 70-80 Fahrenheit for the first 2 weeks. After the bubbling and stabilization inside the vessel has occurred we can put the ferment into cold storage (fridge or cellar) for longer keeping and less softening. If the ferment stays outside of the fridge for a longer time, a deeper taste can develop, as well as the vegetables get softer. It is up to your taste and consistency preferences!
After putting your salted vegetables into their vessels. Now comes the factor of time.
24-72 hours: gram negative bacteria – don’t open
72h -5 days: lots of bubbles! Leuconsitoc bacteria - gram negative bacteria dead
5days - 14days - bubbles slow down - brine decreases (add more if you need) lacto bacillus is abundant!
14days -28days: lactobacillus bacteria populate and make lactic acid. Ph drops - self sterilizing - 4.6 ph
If all of these factors are accounted for appropriately, the pH of the fermentation will drop, lactic acid will build up, the microbial population will consist only of probiotic bacteria, and the vegetable matter will be preserved.