The bottle stage of kombucha brewing is another area where I see people making disastrous mistakes.
All that time spent brewing the perfect brew only to have it spoil in your bottles!
Luckily, there are only a few things we need to do right to make sure your kombucha turns out perfectly.
I’ll cover everything you’ll ever need to know about bottles and kombucha. My aim is, by the end of this article, to answer every question the beginner kombucha brewer may have.
Hopefully, I can provide the information you need to prevent any unnecessary mistakes from ruining your brew.
Let’s dig in.
If you just want to what bottles have finally been working for me you can check them out on Amazon here. Spoiler alert – they are flip top bottle!
What Makes A Good Kombucha Bottle?
So, what makes a good bottle for kombucha in the first place? Well, like most other things, it boils down to a few simple criteria:
- Airtight seal
- Pressure rated glass
- 500 mL or larger
Let’s talk about each one separately.
Having An Air-Tight Seal
When I first made kombucha I made the big mistake of not having air-tight seals on my bottles. I simply re-used old kombucha bottles I bought from the store.
My thinking was that if it was airtight when I bought it, it should be airtight when I brew my own kombucha. Boy, was I wrong!
For whatever reason, the seal on the old bottle was not airtight at all. Instead of my first taste being of a deliciously carbonated homebrewed kombucha, I was instead surprised by a rather flat tasting kombucha (it still tasted great, and I happily drank it anyway.)
If you know anything about creating a seal, you’ll know that metal on glass doesn’t work very well. And the rubber ring on the lid doesn’t work very well for secondary uses.
You need a thick rubber seal to make sure your kombucha bottles are absolutely airtight!
This is why the flip-top bottle is so popular. You can easily use it for multiple batches without having to worry about the seal. If the seal eventually wears out, just replace it!
Why do we care about an airtight seal in the first place?
There are two stages to the kombucha brewing process. The primary ferment, and the secondary ferment.
The secondary ferment is where all of the carbonation is formed. In single batch brewing, the second ferment occurs inside the bottles.
We need the oxygen supply to be cut off, forcing the yeast into fermentation that produces the carbon dioxide and alcohol.
Additionally, we want to trap the carbonation inside the bottle. Any leaks in the bottle are going to both provide oxygen, and let the carbonation escape – The fastest way to a flat kombucha!
Because of the fermentation process of the second ferment, the pressure inside the bottle can build up quite quickly.
This can be a recipe for disaster if your bottle has any weaknesses. The excessive pressure will either lead to a kombucha geyser, or on rare occasions – a bottle explosion.
There are a few best practices you should follow in order to avoid both of these situations:
- Burp your bottles every other day
- Buy brewers bottles – these will be thicker than regular bottles
- Buy round bottles (not square bottoms)
- Inspect your bottles for any defects
Burping your bottles is a process where you briefly release the pressure within your bottles every other day.
Make sure you are only releasing the pressure and not removing all of your carbonation.
As glass is a very brittle material, any sharp points are going to act as stress concentration points.
In other words, decoratively shaped bottles are much more likely to crack under pressure. The best kombucha bottles are those with round body shapes.
In addition to sharp lines, any cracks or dings in your bottle are also going to act as stress concentration points.
Most of the bottle explosions that happen during brewing are caused by cracks in the bottle.
Before you pour your kombucha into the bottles, do a quick inspection for any cracks. You’ll thank me later!
Look for bottles that can handle at least 4 bar of pressure!
A bottle that can handle 4 bar of pressure is going to have no problem with kombucha.
With so much pressure building up inside your bottles it can be very challenging to unscrew the lid if the pressure builds up – this is why flip-top bottles are so crucial.
Once you know how to burp correctly you should have no issues with exploding bottles.
500 mL or Larger
While this usually boils down to personal preference, I find that any bottles smaller than 500 mL just don’t cut it. They take up more room, take longer to bottle, and are more difficult to clean.
By no means are smaller bottles a game changer. You can still get away with 250 mL bottles. This is just some friendly advice that comes from my experiences.
1 L bottles are also a good option. Especially if you are going to be bringing the kombucha somewhere to share.
Personally, 500 mL bottles are a perfect size. You can fill 6 bottles with 1-gallon of kombucha and still have enough kombucha left over for the starter liquid for the next batch.
How Many Bottles Do I Need?
Most people start off will 1-gallon brewing vessels. Additionally, most people usually start out using 500 mL flip-top bottles.
This means you will need at least 6 bottles to hold the 1-gallon of kombucha while still leaving some left over for the starter liquid.
The good news is, most 500 mL kombucha bottles come in 6 or 12 packs.
You can easily adjust the calculations for your specific case. Brewing with 2-gallons? You need 12 bottles. Using 1 L bottles? You’ll only need 3.
For batch brewing with a 1-gallon vessel, I like to have at least 12 bottles on hand. This way I don’t have to worry about finishing the first batch of kombucha before I start my second batch.
What’s Better – Flip-top or Twist On?
The only two viable options for kombucha are flip-top and twist on bottles. I highly recommend you don’t use beer bottles. I’ve had a beer bottle explode on me after letting it sit for 2 days during the second ferment.
9 times out of 10 you will see kombucha brewers using flip-top bottles. There are a few reasons why:
- Airtight seal
- Easy to open
- Easy to burp
As I mentioned above, having an airtight seal is essential. The best way to do this is to have a thick rubber gasket to press tightly against a sealed surface.
Exactly what flip-top bottles have.
If you find the seal starts to wear out over the years you can easily purchase replacement seals for a few dollars.
Because the seals are so replaceable, flip-top bottles can be used for years without having to be replaced.
As long as you are burping them on occasion during the second ferment, the cap on the flip-top bottles will be easy to open.
I find they are much easier to open compared to twist-on bottle caps. If you are still having trouble, this usually means your bottle will need to be “broken in” a little.
They usually become much easier to open as time goes on.
Granted, flip-top bottles are slightly more expensive, but I feel it’s worth paying a few extra dollars to avoid a kombucha bottle explosion!
Especially if you are new to kombucha brewing and don’t quite understand the process yet.
If you’re fine with the risk, store-bought twist on bottles are also a fine option.
You need to make sure the lids are F217 or polycone seal caps. Without these caps, you will have a difficult time holding in any of the carbonation during the second ferment.
Similar to flip-top bottles, these caps can easily be replaced if you find the gasket is wearing out.
Bottle Types To Avoid
Recycled Store-Bought Bottles
Some people have recommended you recycle the kombucha bottles you’ve bought from the store. Personally, I haven’t had much luck using this method.
Unless you have special grips to hold tightly onto the caps, it’s difficult to get the seal tight enough to hold in the carbonation.
I find that the seals used on these bottles are only good for a few reseals before they eventually wear out.
You may be able to get away with one or two brews, but then the seal will start to wear out and you’ll have to buy another store-bought bottle.
As you can guess, this will be much more expensive over the long run.
Similar to the recycled bottles, I haven’t been able to get a good seal. I’ve tried a few times because I have lots of old mason jars sitting around, but I just haven’t been able to get it to work.
My guess is the seal is too thin to get the airtight seal required. If you aren’t concerned with carbonation, then mason jars will be perfectly fine.
Because they are so cheap and easy to find, beer bottles would have been a great option for kombucha.
Unfortunately, they are the most dangerous bottle you can be using.
The mechanism you use to seal the bottles doesn’t allow for the cap to release if the pressure becomes too much for the bottle.
This means, if your carbonation levels become too high, the only way the pressure will be released is by breaking the bottle.
In fact, this exact thing happened to me when I was experimenting. Luckily, I was no-where near the bottle when it exploded.
It did make an interesting sound and left quite a mess. I recommend you avoid these bottles altogether.
How To Bottle Kombucha
Bottling your kombucha is actually very simple.
- Add any flavoring agent: if you want to flavor your kombucha during the second ferment, this is when you do it. Add whatever it is you are using (fruit, ginger, cinnamon, etc.) into the bottle.
- Fill your bottle with kombucha: carefully pour your kombucha from the vessel into the jar. You’ll need to use a funnel if you are pouring from a batch vessel.Avoid using filtered funnels. The filters remove much of the yeast that you’ll need to get that carbonation.You want to fill the bottle right to the flip-top wiring. This allows for a little extra room for your carbonation to build up. If you are using a continuous brewing method, you can pour directly from the spigot.
- Let the kombucha carbonate: let the bottles sit at room temperature for 3-4 days (or longer if needed.) Once you have gotten the right carbonation and flavor, put the bottles in the fridge.The length you let them sit at room temperature is going to depend on the season. The second ferment usually takes a few more days in the winter compared to the summer.Just check on your bottles daily to test the carbonation level. You do this by slightly opening the flip top to listen to how much CO2 is escaping. Once you are satisfied you can move them to the fridge.Placing them in the fridge is going to allow the CO2 to be absorbed in the kombucha and will prevent kombucha geysers!
Changing The Flavor During Bottling
You actually still have a lot of control over the brew when you bottle. By adding different additives (fruit, sugar, ginger, ext.) to the bottle, you can change the flavor profile, as well as the carbonation levels, of the final brew.
For instance, if sugar is added to the kombucha at bottling time, whether as pure sugar or some kind of fruit, the yeast reawakens and begin and secondary ferment.
Because there is no supply of oxygen, this ferment produces a lot of carbon dioxide.
Therefore, a great way to get a more fizzy beverage is to add in a little fruit juice, or pieces of fruit, during the bottling stage.
Even without the addition of sugar, the yeast will continue to ferment in the bottle. This is where all of your carbonation is going to come from.
Leaving out the bottles for 3-4 days will allow this carbonation to build up. Once you are happy with the carbonation level and taste of the bottles, place them in the fridge to stop the fermentation.
How To Prevent A Kombucha Explosion
There are two situations where kombucha brewing can be dangerous.
- Not using food-safe equipment
- Kombucha explosions
I cover everything you need to know about choosing the right brewing vessel in this article.
Kombucha explosions are completely avoidable. They occur when carbonation inside the bottle is allowed to build up beyond what the bottles can handle. The most common reasons for bottles exploding are:
- Using cheap bottles
- Using the wrong type of bottle
In most cases, when I asked the person where they bought their bottles they usually inform me they bought them from Walmart. The prices are usually much cheaper, but you are sacrificing on the thickness of the bottle.
Additionally, the quality control is usually less. This leads to defects being present in the bottles which leads to cracks and explosions.
Another way that leads to explosions is by using the wrong type of bottle.
Specifically, the type of cap on the bottle. As I mentioned above, there are only two ways the pressure is going to be released naturally – by popping the cap, or by the bottle exploding.
This is why beer bottles have a tendency to explode when using them for kombucha. Similarly, twist-on caps will result in an explosion if the carbonation becomes too much.
If you don’t have flip-top bottles, all you have to do to prevent explosions is “burp” the bottles occasionally.
Burping the bottles during the second ferment – unscrewing the cap slightly to release some of the carbon dioxide and then tightly resealing – also removes the risk of explosion.
The act of burping bottles is still controversial in the brewing community. I recommend new brewers burp their bottles until they have a good feel for how much carbonation is building up in their bottles.
How Do I Know When To Burp My Bottles?
The easiest way to know when to burp your bottles is to check daily. After 2 days, slowly release the flip-top mechanism and listen closely to the amount of CO2 escaping.
If you don’t hear any that means your bottles still have a few more days left until they build the right amount of carbonation. If you feel a lot of pressure trying to escape that means it’s time to put the bottles in the fridge!
The bubbles collecting a the top of your brew is a good indicator of how much carbonation is building in your bottles. The more bubbles, the higher the pressure is inside your bottle.
This is why I usually recommend beginners use clear bottles instead of brown. Until you know how much carbonation your recipe will produce, it’s best to be able to check the bubbles for extreme carbonation.
If you’re afraid of an explosion, or can’t get the lid off, wrap a towel around the bottles to protect yourself if things take a turn for the worse!