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Continuous brew! the way of the ancients!

Kombucha Bubbles: How to Increase Carbonation…for Beginners

One of the most common questions homebrewers have is how to get more carbonation (i.e. fun bubbles) in their Kombucha. Yes, bubbles are fun, and there is something inherently exciting about seeing a fizzy glass of iced Kombucha froth over the edge as you pour.

Beautiful carbonation bubbles rise through amber liquid.

Bubbles add flavor and texture, scientists say.

It emphasizes the “living” energy of the drink, and because it’s natural, it feels and tastes different than CO2 that is added.

Let’s get the basics down before we dive into the solutions:

What is Carbonation?

When CO2 (Carbon Dioxide) dissolves into a liquid and is kept under some pressure, carbonation results. When that pressure is released, so are the bubbles, and that brings the lip tickles.

What causes Carbonation?

As always, there are the natural and the man-made versions. “Forced carbonation” involves mechanically adding Carbon Dioxide while a liquid is under pressure. Natural carbonation requires only the magic of fermentation and a closed container.

But wait! Kombucha is fermented in an open container, uses a cloth cover and requires air circulation. How can CO2 build up? The answer is your SCOBY. As it grows on top, it makes an airtight seal to the sides of the brewing vessel, trapping the newly created gasses inside. Have you noticed your SCOBY developing a lot of holes or bumps? If so, that is the CO2 (and other gasses) trying to escape. Totally normal.

Kombucha Carbonation: What to Expect?

So why isn’t your Kombucha bubbly? Let’s talk about expectations. Most people have experienced carbonation in two forms: soft drinks and beer. In both cases, almost all the products sold on shelves undergo what is called a forced carbonation process, where CO2 is literally forced into the beverage and kept under pressure to maintain the effect. Beer is usually somewhat naturally carbonated but rarely goes to shelf without a boost, usually of the forced carb variety. Modern day commercial sodas have zero natural carbonation, and anyone who has ever accidentally sipped a flat soda knows they are undrinkable without bubbles.

What’s important is that in both cases, the carbonation produces artificial bubbling when poured, and if you pay closer attention, you will be able to tell the difference. Artificial bubbles tend to be more uniform, stick to the side of the glass and do not tend to “interlace” each other. They also dissipate more quickly, are more “aggressive” in the mouth and have a much “harder” taste to them. Natural carbonation, even when it causes the bottle to explode on opening, delivers softer bubbles that tickle rather than burn and look a little more soap-like.

All this is to say that when some complain about their homebrew not being “fizzy enough,” it may just be a matter of perspective. When I pour a glass, sometimes it fizzes up and sometimes it just bubbles along the side of the glass. A little carbonation can go a along way, especially if one is not expecting their Kombucha to look like a Coke when it’s poured. Be more sensitive to the bubbles that are present and you may find your Kombucha is plenty carbonated just as it is.

But I Want More Carbonation! Help!

Okay, okay. I’ve given you the background info and warned you to really be present with your Kombucha and think about if the bubbles are already doing what they are supposed to do. Now it’s time for the tips.

These tips are the easy ways to get carbonation, so I’m labeling them as “Beginner.” The truth is, these are the only techniques I use regularly. Next week, I will post “Advanced” techniques for increasing carbonation. Again, any brewing level can attempt any of these tricks, but the advanced level ones require a more adventurous brewer.

Secondary Fermentation

The easiest ways to get additional bubbles are in the bottling process. Whether you are using the Batch Brew method or the Continuous Brew method, you must bottle your booch to make it effervescent. During this bottling period, the beverage will undergo a period called “secondary fermentation.” Depending on the conditions, either a little or a lot of fizz will be created, and you may even have an exploding (yes exploding!) bottle problem on your hand if you don’t monitor them well!  As part of this stage, there are 3 tricks to employ. You can use one, 2 or all 3 techniques.

The common requirement for all of these methods is: You must have a tight cap for your bottles. Reusable bottles are GREAT, but often the caps do not hold bubbles in well. If you are still unable to get the fizz you want after trying these techniques, try better bottles. You can look for Italian made locking swing top bottles or buy a few Grolsch, enjoy the beer and then reuse those.

  • Fill Your Bottles Completely – Like all the way to the top, leaving just a centimeter or two of space. By reducing the amount of oxygen present in the bottle, more Carbon Dioxide is dissolved into the Kombucha. This stage is also known as the anaerobic fermentation stage, meaning “without air.” In your Continuous Brew or Batch Brew, the fermentation was aerobic (although, under the SCOBY there’s a bit of anaerobic happening also, but I digress). Now we are starving the liquid of oxygen, which induces a different type of action among the yeast and bacteria, which then produces more bubbles, among other things.
  • Add A Little Sugar – What? Sugar? Yes! Sugar is what sparks yeast the most, and the yeast are responsible for the bubbles. You can use a 1/2 teaspoon of plain white sugar per 12oz bottle, and that’s what many beers do to create carbonation, but Kombucha mixes much more symbiotically with pieces of or pureed fruit and juice or other natural sugar sources, and the resulting bubbles can be quite explosive. Frozen, fresh or dried fruit all work equally well and spark both the flavor and fizz of many of my favorite recipes.Another fine choice is fresh ginger, cut into centimeter sized blocks or grated (freeze first to make this easier). Of course fresh ginger is extremely healthful, goes great with lemon juice or any fruit and tends to produce a spicy, more aggressive fizz. About an ounce, or 8-10 small pieces is what I use for a quart sized container, but find your own taste preference. You will see that the Kombucha literally sucks all the life out of these little pieces of organic material, usually leaving them blanched of color and limp.Bonus Tip: The most powerful fizz inducer might be Strawberry Puree! My advice: open over the sink.
  • Leave Them Out of the Fridge – Once you’ve got that Kombucha all bottled up tight with very little air (flavorings optional), it’s time to sock it away somewhere dark and warm if possible. We are no longer concerned with airflow. In fact, the less the better, so in a cupboard or any other enclosed space is just fine; avoid sunlight. How long you leave them out is up to you. The more flavorings you have added, the more closely you need to monitor your bottles, potentially burping them to prevent an accident. Give them at least 2-3 days, then you can move them to cold storage if you like. Mine rarely go into the fridge and continue to ferment in the bottle. I enjoy the deep flavoring.

Those are the basics. Tried these and still not getting any fizz? Next week we’ll cover advanced techniques for improving carbonation naturally that require changes to the brewing method plus a multiple stage secondary ferment for the adventurous.

Hannah Crum, the Kombucha Mamma!Hannah Crum is The Kombucha Mamma, founder of Kombucha Kamp, Industry Journalist & Master Brewer, educating others about Kombucha since 2004. Connect with her on Google +