Should you make water kefir with an airlock or just cover it with a cloth? Is the process more like kombucha or sauerkraut?
I have been making water kefir for several years now and so far have not used an airlock. I cap the jar tightly during the second ferment to increase carbonation. (An airlock during the second fermentation is a good idea, as I have experienced an explosion due to the build up of gasses.)
Recently my sons and I performed an experiment to test the hypothesis that oxygen is beneficial during the first fermentation period, and therefore a cloth cover is preferable to an airlock. The cloth cover allows oxygen to nourish the growing culture. The airlock keeps oxygen away, but allows carbon dioxide to escape. This is vital for vegetable ferments such as sauerkraut or kimchi, but not healthy for ferments that need oxygen such as kombucha or wine.
What are water kefir grains? They are similar in nature to a kombucha SCOBY (Symbiotic Colony of Bacteria and Yeast.)
The scientific name given to water kefir grains is tibicos, which according to wikipedia, “are a culture of bacteria and yeasts held together in a polysaccharide biofilm matrix created by the bacteria.”
Fundamentally, yeasts require oxygen in order to grow. If your grains multiply during the initial fermentation, it is a sign the culture is successful.
We started with two half gallon jars, filling each with the same amount of grains (3 ounces), sugar, and water. We added the same amount of molasses to each. (Molasses offers a nice boost for the grains since they thrive on minerals as well as sugar.) We covered the first with a cloth, the second with an airlock.
After 48 hours, we strained both and weighed the grains.
Colin performed his own experiment with similar results. Read his account here.
While our experiment tells me that either method is acceptable, I think I’ll keep letting my kefir breathe during the first ferment.
Would you like to perform your own experiment, or make your own water kefir? View the recipe here.