Kefir Soda FAQs

Important! This product creates strong carbonation. Use thick flip-top bottles made for brewing, not from a craft store. Remember to carefully burp the bottle often, to release pressure

  • Will I need to look after crystals if I use the Kefir Soda Starter? No. Our Kefir Soda Starter is a powder that dissolves in liquid and does not create crystals at any stage. Once you've made a batch of Kefir Soda using our Kefir Soda Starter, you can use some of it to culture your next batch. This is called 'reculturing' and can be repeated several times over.  
  • Which liquid should I use? Use 100% fruit juice (homemade or store-bought with the least additives possible) or coconut water. You will also need water, preferably lightly filtered or spring (not fizzy).
  • Can I use juice made from frozen concentrate? Yes, you can use juice that was originally made from frozen concentrate. Ideally, the juice should be at room temperature when you make the recipe. The bacteria perform best at pleasant ambient temperatures. If your kitchen is on the colder side and you use refrigerated juice, you may want to take it out of the fridge ahead of time, so that the juice is not too cold when you make the recipe. This is less of an issue in the summer because a cold liquid left on the counter will naturally reach room temperature fast. Opt for juice with the least additives possible. If you make the juice yourself, do not over-dilute it. The bacteria need the naturally-occurring sugar in the juice to feed on.
  • Can I use a canning jar to ferment in? No, this doesn’t work and will leak out the carbonation. 
  • What kind of bottles should I use? Use thick 32 oz flip-top bottles made for brewing. Do not use craft-store bottles. These may not handle pressure well, and may explode. You can also use recycled store-bought kombucha bottles.
  • Why do I need to leave some headspace in the bottle? To let the mixture expand. Fermentation creates natural gas which causes the mixture to increase in volume.
  • Why do I need to burp the bottle often? Fermentation produces strong carbonation which creates high pressure in the bottle. Recultured batches carbonate even stronger and faster. Carefully burp them often (daily, as needed), even when in the refrigerator. See also 'How to pop the top?'
  • How to pop the top? Carefully, gradually, and not directly towards your face. While firmly pressing down on the top of the bottle with your palm, release the flip gradually. Gently and repeatedly alternate between firmly pressing your palm on the top of the bottle and releasing it slightly, so that the pressure can gradually escape in small hisses, without "erupting".
  • How long does an unopened sachet of starter culture keep in the refrigerator? The Best By date is printed on the pouch and on each sachet. Keep the starter culture refrigerated/frozen.
  • How long will the bottle of kefir soda keep in the fridge? It will be good for 1-2 weeks. Flavor and fizz may change/weaken over time.
  • Can I use less than ½ cup from my previous kefir soda to ferment a new bottle? You will need to experiment. If the result is weak, you could try extending the fermentation time.
  • Is fermentation affected by the temperature in my house? Yes. Warm temperature will accelerate fermentation (carbonation), while cooler temperatures will slow it down. The ideal temperature for fermenting is around 70-75°F.
  • What could affect fermentation (carbonation)?
    • Ambient temperature: the warmer the temperature, the faster and stronger the carbonation.
    • Strength of starter: the stronger the starter, the faster and stronger the carbonation.
    • Amount of natural sugar in the mixture (from the juice or coconut water): the sweeter the mixture, the faster and stronger the carbonation.
    • Ratios of water-starter-sweet liquid: the more starter and sweet liquid there is, the faster and stronger the carbonation.
    • Duration: There’s a sweet spot during fermentation, where your bottle is nicely carbonated, pleasantly tangy, and has lost quite a bit of its initial sweetness. That’s when it needs to go in the fridge. Any longer than that on the counter, and fermentation may weaken or, conversely, overly-fizz. Gently open your bottle often, to release pressure.

Because of these many variables, you’ll need to experiment a little to find what works best for you. Use our basic recipe as a general guideline. Sometimes you may need to ferment for a little longer or a little shorter, or use a bit more starter or a bit less, or use more juice or less.

  • How many times can I reculture? For as long as your bottle comes out pleasantly fizzy and tangy.
  • Can I make larger quantities? Absolutely! You can do this starting at the 2nd batch, with all the ingredients in proportion. For example, to make 2 bottles, just double the quantities: use 1 cup of your kefir soda from the first bottle as a starter, 4 cups of juice or coconut water, and just under 3 cups of water. Mix well and pour evenly into your brewing bottles.
  • Is there sugar in the kefir soda beverage? Much of the original natural sugar from the juice/coconut water is consumed by the starter bacteria and yeasts during fermentation, and is used to produce carbonation. Our research shows a decrease of up to 82% in sugar content. Sugar content will also depend on the juice you use and on fermentation length. As fermentation progresses, more sugar is metabolized by the microorganisms, and less of it is left in the liquid. The starter itself contains no sugar, nor is sugar added to the recipe. The natural sugar in the juice/coconut water is food for the bacteria and yeasts, and is needed in order for fermentation and carbonation to occur. See research
  • Is the starter gluten-free/dairy-free/lactose-free/vegan? Although the starter contains no animal products, no gluten, and no dairy (and hence no lactose), it is packaged in a shared facility that also handles products that may contain wheat, soy, eggs, milk, and fish.
  • Is the starter certified Kosher? No. Our starters are not certified Kosher.
  • Where is the starter made? In the USA.
  • I live in a hot place. Is the starter still active after being shipped unrefrigerated in hot weather? Yes. Our starters are designed to remain active for several weeks in non-refrigerated transit in warm weather, without the need for express shipping or ice. The formula and the packaging provide excellent protection for the live strains. For this reason, we use ambient shipping (which is also significantly less costly for the customer). The starters are kept cold in our warehouse until your order is ready for shipping, and when your order is shipped, we send you the tracking number so that you can see when it is due to arrive. Even if left in direct sunlight for a couple of hours, the starter's viability will not be impacted by much, because reduction in viability is a slow process that does not happen immediately. Once received, the starter should be refrigerated (or frozen), and you can use it as normal. Your bottle should come out well-carbonated and tangy. See also 'I forgot to refrigerate the starter. Is it still active?'
  • I forgot to refrigerate the starter. Is it still active? This depends on how long the starter has been left at ambient temperature and if the Best By date is still valid. The starter is designed to remain active for several weeks at ambient/warm temperatures (usually for transit purposes). The formula and the packaging provide excellent protection for the live strains. If the delay is much longer and the temperatures are very high, the viability may be affected. That said, reduction in viability is a slow process that does not happen immediately, even past Best By date. You could try compensating for the possible decrease in viability by fermenting for a little longer, to let the bacteria 'catch up' by proliferation over time. Remember to pop the top often to release pressure. See instructions. Your bottle should come out well-carbonated and tangy. There's no harm in consuming inactive bacteria; this is equivalent to consuming no bacteria at all. If all goes well, you could later use some of your ready batch to make future batches. Remember to ​​​​​​keep the starter refrigerated (or frozen) until you're ready to use it. See also 'I live in a hot place. Is the starter still active after being shipped unrefrigerated in hot weather?'

Kefir Soda starter

Need more info?
Go to Kefir Soda Research 

Go to Kefir Soda basic recipe instructions
Go to Kefir Soda Fun & Fizzy Recipes