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When first starting out making water kefir you may find that your water kefir has become flat even after your grains are fully activated. The cause is usually one of three things; ambient temperature, sugar ratio or fermentation time.
Water kefir grains harbor lactic acid bacteria and yeast which consume sugar to produce CO2. These cultures need adequate heat, sugar and time to produce enough CO2 for carbonation. Fermenting with active an culture at 25˚C with a sugar ratio of 1:20 for 24-48 hours will result in carbonation.
There are two types of microorganisms in water kefir which produce CO2 lactic acid bacteria and yeasts. It is through the action of these organisms that your water kefir becomes carbonated. If the second fermentation process is not producing enough carbonation it is usually one of three things:
The Ambient temperature is too low for efficient growth
After the first fermentation of the sweet water solution and the water kefir grains have been filtered out what remains is a slightly sour effervescent liquid which has live yeast and lactic acid cultures in it. kefir grains will provide several species of both the yeast and lactic acid bacteria making the water kefir a great probiotic drink.
These various species have different optimum temperatures which they grow at so the temperature for optimum CO2 production will vary depending on the makeup of the culture.
Most yeast cultures like temperatures between 20-35˚C. but can remain active at 39˚C. Lactic acid bacteria perform best between 18-30˚C. This gives you a range of anywhere between 20-30˚C for adequate microbial action.
If your house temperature is on the cool side or if it cycles warm and cold depending on the time of day then this can affect the growth of the cultures. water kefir likes a steady temperature for best results so if this is the case then find a location which you can keep at a constant temperature between 20-30˚C.
The sugar content of your water kefir is too low
The cultures in the water kefir need energy to grow which it gets from the added sugar which you feed it when you bottle it. This sugar can come in a variety of sources like fruit juice, cane sugar, brown sugar or any other sweet additive you want.
Without enough food the cultures cannot grow and they will not produce enough CO2 to carbonate the water kefir. Flavorings like fruit juice have adequate sugar in them if the ratio is about 1:10 juice to water kefir but if you are flavoring with herbs and/or spices then you need to add some sugar as well with ginger being the exception. Ginger does need some additional sweetener but be careful as ginger produces volumes amounts to carbonation on its own.
The second fermentation time is too short
Depending on how active your water kefir culture is will influence how long you will need to leave your bottled water kefir to carbonate.
The activity level of the cultures in the original ferment can be evaluated by its sweetness after 24-48 hours. If it is sweet with very little tartness or effervescence then the culture is not very active and will need more time to carbonate once bottled.
To adequately carbonate your water kefir you have two options:
- Leave the water kefir another 24 hours to allow the population of yeast cells and bacteria to increase
- Leave the bottled kefir another 24 hours to allow the culture to produce more CO2
Each of these actions will give the cultures a chance to multiply and produce more CO2.
How to make your water kefir fizzier
If you are providing the right amount of sugar, time and temperature but still your water kefir does not carbonate enough for you then there are other things you should be aware of.
The health of the water kefir grains
Water kefir grains are made up of polysaccharides which harbor the live cultures which ferment the sweet water and make kefir. If they are not healthy and robust they will have a hard time multiplying in fresh sweet liquid. This makes for a sluggish ferment which will not completely use the available sugar in the liquid.
This could happen for a number of reasons
- The cultures do not have enough nutrients to grow
Just like other living things the cultures in your kefir grains need more than just sugar to live. They also need vitamins and minerals. If your grains are sluggish during the first ferment but still produce enough carbonation in the second ferment given extra time then this could be your problem.
Usually the second ferment is flavored with added organic materials such as fruit juice or herbs and spices. These added materials provide the additional nutrients which the culture needs to grow efficiently. This leads to adequate carbonation in a longer period of time.
To adjust this try adding minerals to your first ferment by using unrefined sugars like raw sugar, brown sugar or other plant based sweeteners like coconut, palm or beet. Another option is to add yeast nutrient to the water which is used for winemaking.
- The ratio of grains to liquid is not correct
The cultures can only grow so fast so if you are using too few grains to make the amount of kefir you want you will get a sluggish second ferment.
Try lowering your ratio until your grains have grown enough to properly culture your target volume.
- It is stored in direct sunlight
Sunlight can inhibit the growth of some of the yeast and bacteria species in your water kefir. Placing it in a warm location out of direct sunlight will help the culture to grow at optimal rates. Find a warm cupboard somewhere like on top of the fridge or some other heat source.
- Added sweetener is high in complex sugars
Although complex sugars can be sweet to us it doesn’t mean that it is sweet to your grains. Complex sugars which have long chain polysaccharides in them are difficult for the yeast and lactic acid bacteria to break down.
Ensure the sweetener you are using has enough simple sugars available to the CO2 producing species in the water kefir. Sweeteners like artificial sweeteners, stevia or yacon syrup cannot be used by the water kefir culture for growth and therefor will not produce any CO2 for carbonation. If you want to use these types of sugars they will provide sweetness so if you want sweet kefir soda then use them but be sure to provide some form of simple sugar for the culture to consume.
If my kefir soda isn’t fizzy are my grains dead?
First the grains themselves are not alive. It is the various species of bacteria and yeast which inhabit the grains which are alive. That means that for the grains to be dead all the strains in the grain have died. This is not likely.
Yeast and bacterial cultures are very hardy, they have various methods of protecting themselves from slowing their metabolisms down to growing spores for later so it is very hard to kill your grains. It is more likely that one of the above conditions is limiting their growth so try changing some of these things and reduce the amount of water kefir you are making until the first fermentation produces slightly tangy good tasting water kefir.
How to tell the carbonation level of your kefir soda
If you are using swing top jars to bottle your water kefir it will be difficult to determine when it is ready. You could open one bottle after 24 hours to determine how much pressure it in it but this will release some CO2 making it less carbonated.
Another option is to use one plastic soda bottle with soft sides. Then you can squeeze to bottle to determine its carbonation level without opening it. This is a great method for when you are first starting to second ferment your water kefir as it will help you determine timing for ideal carbonation.