I know this is a controversial topic with homebrewers,
but spoiler alert (if you couldn’t tell by the headline):
I do not recommend burping my bottles. I just find it
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sections if you like, or just keep scrolling to read it all:
What is burping?
Burping is essentially just opening your bottles ever so slightly during the second fermentation process to release air or “excess pressure” in the bottle. Many brewers recommend burping bottles every day, or every other day while your bottles are fermenting at room temperature.
Do you recommend burping your bottles?
But why not?! Excess pressure in glass bottles sounds scary!
Burping is unnecessary and counterproductive to fermentation.
I know this is controversial because a lot of homebrewers will insist that burping is part of their process. I do not think burping is necessary once you’ve got your process nailed down and once you have a good grasp on the science of the kombucha-making process. In a lot of cases, burping sabotages homebrewers who are trying so hard to build carbonation. It interrupts the second fermentation process. So it’s like your yeast is taking you two steps forward and when you burp, you’re taking one step back. I personally find it to be a waste of time for my process.
I’m also aware that my kombucha brewing process may be different from others’ processes out there. So if you want a full understanding of my process, you can browse around this site for more info. And in particular, you can read my articles on:
Warmer temperatures greatly exaggerate carbonation.
Picture this scenario: You burp your bottles because you want to check in on them and see how fizzy they are. You’ve heard about bottles potentially exploding and you want to avoid that at all costs, so you want to release some of that carbonation. Sounds perfectly reasonable, right? I hear you.
So you burp your bottle at room temperature because of course, second fermentation can only happen at room temperature. Then you see that the liquid and the bubbliness in the bottle is really aggressive. It may even make a mess. So you figure, “My kombucha is really carbonated, I better move it to the fridge to stop it from getting over-carbonated!” But then, after it chills down completely, you open it back up and it’s flat or not very carbonated. What gives?!
A lot of homebrewers say that refrigeration “removes” carbonation from their kombucha. Then I ask them if they burp their bottles and almost every single time, they’ve said yes. So, it’s not really the cold that’s “removing” the carbonation. It’s the burping. The confusion is happening because carbonation is exaggerated at room temperature. Cold liquids hold bubbles better than room temp. So when you chill that liquid, it will be “calmer” and retain the bubbles in the liquid so you can actually drink it instead of end up with a kombucha mess all over the place.
That bottle may not have been “over-carbonated.” It just looked super carbonated because it was at room temperature and room temp liquid can’t hold its liquor...I mean bubbles! Room temp liquid can’t hold its bubbles.
It may have been perfectly fizzy, but when you burped it, you released a bunch of carbonation. Then, when you moved it to the fridge, there wasn't much carbon dioxide left to be trapped in the liquid. (It just looked like there was because warm temps are like push-up bras for bubbles. They just give the illusion of bigger bubbles.) And of course, cold puts your yeast in a state of dormancy so it’s not going to produce any more carbon dioxide in the fridge. So not only is burping unecessary, but it’s misleading as well...
Poor quality glass bottles have given people unfounded fears.
I’ve heard from enough homebrewers to know that glass explosions are a very real and understandable fear. And there are some Facebook kombucha brewers groups that perpetuate this fear without relying on science to find the source of the problem and take steps to avoid it. So what are you supposed to do? I get it. Burping may seem like the best solution to prevent it. But the bottom line is that explosions can happen in poor quality bottles even if you do burp!
I won’t lie that explosions do happen. I’ve even had a bottle explode myself — it was a beer bottle that I used when I was experimenting with alternate sources of cheap bottles. But I took the precaution of keeping it in a closed cabinet, so when the glass broke, it was not a big deal at all...because I was experimenting in a "controlled environment" and I took the steps to prevent the problem.
Whenever I’ve heard about glass exploding, it’s been because of poor quality glass or glass that was not meant to handle food or pressurized contents. They’re always square bottles, pretty colored decorative bottles, IKEA bottles, etc. In the case of my exploding beer bottle, I had left it fermenting for too long on a hot summer day in a beer bottle made of thin glass. So that was definitely the result of my poor choice in using the wrong type of bottle. But I’ve learned from it and through trial and error, I’ve found the right kind of bottles to use for second fermentation.
But now, unfortunately, homebrewing kombucha gets a bad rap for being potentially “dangerous,” and people say that the only way to prevent an explosion is to burp your bottles. But burping bottles only releases good carbonation that the yeasts worked so hard to build up.
The best precaution you can take to prevent an explosion is to just use the right kind of bottle. It’s also a good practice to keep your second fermenting bottles in a cabinet or closed-off vessel like a cooler without ice to contain any potential messes. The most mess I’ve had with a good quality bottle is just the cap unscrewing a bit and the contents leaked out, but by no means did my glass break.
I’ll get off my soap box, but in reality, you don’t need to waste your time burping and you don’t need to worry about glass explosions if you’re using good quality bottles and you understand the fermentation timeline of your particular kombucha culture.
With my scoby, I usually only have to second ferment for 3 days at room temperature before moving to the fridge. Most bottles are perfectly carbonated at that point, with no burping and no fizzy mess. And in the super rare instance that my bottles aren’t fizzy enough, I just take the batch back out, let them ferment at room temp again for another day or so to build more fizz, then move back to the fridge before testing again!
Much more simple than burping!
When is burping a good option?
There is one instance when I do think burping is a good idea. During second fermentation, the longer you let your sealed bottle sit at room temperature, the more the yeasts eat away at the sugar in the bottle to create carbonation. If you want to ferment as much sugar out of your kombucha as possible, that means you’ll have to leave it at room temperature long enough for the yeasts to eat as much sugar as they can.
For example, I usually only second ferment for 3 days before moving to the fridge, but if I wanted a more dry or less sweet kombucha, I may want to ferment for 5 or even 7 or more days. But that means they’ll definitely get over-carbonated and make a mess when I open them. So in that case, I do recommend burping your bottles regularly to release excess pressure. That way, you can continue to keep fermenting them at room temperature until they reach the right sweetness levels (or lack of) and carbonation level that you prefer.
Why I don't burp my kombucha bottles