Fermented drinks such as water kefir and kombucha are fun to make and drink. The bacteria and yeast in the cultures convert the sugars into lactic acid, a very small amount of alcohol, and a lot of carbon dioxide. As the beverage continues to ferment, more and more gas is created. This also means more pressure is created, and too much can cause problems.
FACTORS AFFECTING BOTTLED WATER KEFIR PRESSURE
Kefir goes through two fermentation periods and both are essential to a successful carbonated beverage. During the first period, water kefir grains need enough minerals, sugar, and clean water to be healthy. Once the grains are removed, there is not likely to be a lot of fizz without some extra help. Adding just a small amount of fruit or juice to the second fermentation period will liven things up.
Follow the guidelines in Flavoring Water Kefir to select the best ingredients and amounts for your kefir. Using more juice or fruit than called for speeds fermentation, creating more pressure in the bottle.
The pressure of water kefir can be significant, so choosing high quality bottles is of the utmost importance. Look for a bottle that is heavy for its size, with thick glass. The bale (or wires) on the swing top should be heavy guage and not bend with pressure. The rubber gasket should be pliable and fit snugly.
Check your containers for cracks or other flaws. If you discover any cracks, chips or splits in the glass, discard the bottle and obtain a new one.
The best place to purchase bottles is from a source selling bottles made for high pressure bottling. Check out our 750-ml Grolsch-style bottles.
Time and Temperature
At warmer temperatures, the kefir will ferment much faster. We recommend burping (opening the bottle to release pressure) once a day under normal conditions. If temperatures are over 75°F, it may be necessary to burp bottles more frequently. Once refrigerated, chilled bottles should be burped weekly.
SAFETY WHEN BOTTLING WATER KEFIR
It can be a little nerve-wracking to go back to making fizzy kefir once a bottle explodes. To contain the bottles and ease the nerves, place fermenting bottles in a box or other container. Plastic storage totes are convenient for housing actively fermenting soda. If a bottle does explode, everything is contained.
If a full bottle has not been burped for awhile, take it outside and cover with a dishtowel or hand towel. Wrap it up and point the top of the bottle away from faces or anything breakable. Use the towel to help pry the bale out and up. The towel will absorb any excess soda.
Kefir sodas are delicious, nutritious and a great alternative to commercial sodas. Exercise a little caution and common sense to enjoy the bubbles in your glass instead of on the ceiling.