Carbonating your Root Beer with Yeast

Before I explain how to carbonate your root beer with yeast, let me give a small overview about the process, and a few words of warning.  If you already know all this, you can skip down to the instructions at the bottom for how to actually use the yeast.

When you put yeast in sugar water at room temperature, it will create carbon dioxide and alcohol, and carbonate the water it is in.  Similarly, if you put it in root beer or a soft drink, it will carbonate your root beer.  There are several advantages and disadvantages to this technique. The primary advantage is cost - yeast is very, very cheap, and you can get it anywhere from the grocery store to your local beer home brew shop. There are, however, a few things to keep in mind.  

One small problem is that it adds a slight off taste to your root beer.  Depending on which yeast you use, you will get a different off flavor.  Ale yeasts add a beer flavor and smell to your root beer.  Champagne yeast adds a slight fruity flavor to your root beer.  Letting the yeast sit for a week or so in the refridgerator after it has carbonated will cause the yeast to crash out and will reduce the flavor it adds to the root beer, which helps some.  Personally, I have never successfully gotten rid of the flavor entirely, but I have gotten it to be drinkable.  I have not experimented that much with this method however, and there may be ways to use yeast without getting an off flavor.  That's something I intend to experiment with more at some point.

Another disadvantage to yeast is that to make yeast survive and carbonate your root beer, you must leave your root beer out at room temperature for a few days.  This can allow other bacteria in your root beer to grow, which can add some really nasty flavors to your root beer if you are not careful.  Therefore, whenever you use yeast, you must clean all of your equipment very thoroughly, boiling utensils, soaking bottles in a bleach solution, or using disinfecting solutions from your local beer brewing store.  If you take care, you can avoid flavors from other bacteria.

Yeast will also create alcohol in addition to the carbon dioxide.  If you cool your yeast as soon as the root beer is carbonated, this is not a problem, as the amount of alcohol will be incredibly small (less than that in glass of natural orange juice).  For example, this recipe is intended for teachers to use in their chemistry labs, which the children then drink. It was lab tested and proven to be between 0.35% and 0.5% alcohol. It is such a small amount it is not worth worrying about. Still, this is worrisome to some people.

Lastly, yeast is sort of unstable.  It will continue to create CO2 and pressure until you put it in the refridgerator (or with some yeasts, even the refridgerator isn't cool enough to stop it from carbonating).  If the pressure gets great enough, you can blow up bottles. This is quite dangerous, especially If they are glass bottles.  You don't want to be near a glass bottle that explodes.  Therefore, it is best to use plastic soda bottles when carbonating, so you can squeeze the bottle regularly to test the pressure and help prevent an explosion.  Also, plastic soda bottles are less likely to explode, and if they do they will probably do less damage (you will end up with a mess for sure, but hopefully nothing embedded in your body and walls).  Some people do use glass bottles without any problem, but it is just something to watch out for and be careful of.

 With those seemingly many disadvantages, none of them are that great if you take care and know what they are ahead of time.  Many people use yeast and are quite fine with it, and I recommend it for people who want to be a hobby root beer brewer without too much cost.  So if you still want to carbonate your root beer with yeast, here are the instructions!

Instructions for Yeast Carbonating Root Beer

Ingredients:

1/8 tsp yeast (preferably ale yeast)
Non-carbonated Root Beer wort (or anything else you want to carbonate), in a 2-liter plastic pop bottle with a cap

Equipment:

Thermometer (sterilized) 

1. Before you create your root beer, you must clean EVERY utensil, bottle, or anything that is going to touch your root beer thoroughly.  This means boiling it, soaking it in a bleach solution, or cleaning it with a disinfecting cleaner or no rinse solution that you can get from your home brew store.   I usually put all of my metal or small plastic cooking utensils in a pan and boil them for 10 minutes or so, and make a bleach solution of around 1 tbsp per gallon of water or so.  Also, make sure to boil your root beer wort so it is pasteurized as well.

2. Make your root beer, soft drink, or whatever you want to carbonate. 

3. After you have created your root beer with clean utensils, cool the root beer to room temperature.  No more, no less.  I often leave the root beer in my pan, put it in the kitchen sink with ice water to cool it, bottle it in my plastic 2-liter bottle, then it it come back up to room temperature.  You may want to check the temperature with a sterilized thermometer.  You can find the active temperature for your yeast usually on the packaging or online, so you can check it against that temperature, but around 70F should be fine.

Usually when I have had a problem, it is on this step.  If the temperature is too high, the yeast will die and you won't get any carbonation.  If the temperature is too low, it will take a while for the yeast to start carbonating, but I think it will still work, so err on the side of too low if you have to.

4. Add 1/8 tsp of yeast to the root beer, and cap it.  I usually also cover it with a towel to block out the light, because sometimes light can cause off flavors. At least, that's what I've been told for some beers.

5. Once a day or more, squeeze the bottle to see if it is tight.  As soon as it is tight, put it in the fridge right away.  It shouldn't take much more than a few days to get to the right pressure.  You should notice it getting noticeably more tight after a day.  For an example of how tight to make it, feel a bottle of pop at the store that is unopened - it will be pressurized to near the right amount.

6. After putting it in the fridge, let it sit for a few days or a week for the yeast to crash out.  You will notice the yeast settling to the bottom of the container.  This is normal.  If you are using a yeast other than ale yeast, make sure to depressurize the bottle every day or two to make sure it doesn't explode.

7. Now it's ready to drink!  The yeast residue on the bottom of the bottle is normal, but does have some taste.  When you pour, try to avoid stirring up the yeast too much, and try to avoid getting any in your glass.  Just pour slowly and don't tilt the bottle too much, letting the bottleneck keep the yeast in the bottle.  The yeast is fine and will not be bad if you get it in your cup, it will just add a different taste (which some people like). 

 WARNING: If you let  the bottle sit for too long before you put it in the refridgerator, and it gets too pressurized, it can explode.  This is why it is a bad idea to use glass bottles.  So use plastic bottles for safety, and check them regularly. 

WARNING: Some kinds of yeast stay active even when they are lowered to fridge temperatures.  Ale yeasts should go dormant, but champagne yeast, baker's yeast from the store, and many other yeasts will continue to ferment.  That means they will continue to build up pressure even in the fridge, and can explode.  Therefore, if you use one of those kinds of yeast, make sure to open the bottle periodically to release pressure and make sure to squeeze the bottle fairly often to make sure it is not too pressurized.  Also try to drink it fairly quickly.  Since the fermentation is still going on, if you drink it too slowly you will also build up alcohol and make the drink alcholic.  That would probably be bad if you are serving it to kids or bringing it to work!

WARNING:  If you use ale yeast it will taste and smell a bit like beer.  I would not suggest bringing it out to drink at work, or leaving it in an open container in the car.  You and I know it is perfectly safe, but your boss or the nice police officer might not believe you.   :)

 Types of Yeast

There are various kinds of yeast you can try for making root beer.  I'll probably make an article later discussing various kinds of yeast in more detail.  For now I'll just say that the only ones I have tried are ale yeast and champagne yeast.  To me, the ale yeast adds too much of a beer flavor, and I don't like it, but it is much safer to use because it will go dormant in the refridgerator. 

Champagne yeast adds a fruity flavor, which I also didn't care much for, but it tasted better to me than ale yeast.  On the other hand, champagne yeast will continue to ferment in the refridgerator (although it does slow), so you need to make sure to periodically release pressure, and drink it fairly quickly.

I've heard that baker's yeast works as well, but I've heard it adds a very strong taste, and it will continue to ferment at cold temperatures as well.

I plan to try other yeasts in the future and try different things to see if I can reduce the flavor more.  I've never successfully gotten rid of the flavor entirely, but it is drinkable.

Making Alcoholic Root Beer

I haven't tried this, but the yeast will continue to add alcohol until it uses up all the sugar, dies from lack of nutrition, or dies from too much alcohol.  So if you want an alcohol root beer, just loosen the cap on the root beer so it doesn't explode and leave it at room temperature for longer.  I think for real beer it takes a few weeks to ferment and use up all of the sugar. 

Different yeasts die at different alcohol levels, so if you want a really high alcohol level you might need to use something other than ale yeast, like champagne yeast.  You'll also need to probably put more sugar in your root beer if you want it to produce much alcohol and still have sugar leftover to make it taste good.  And you might need to add some nutrients to the root beer for the yeast to survive for a long time.  You can add a little molasses, or you can buy yeast nutrirents at your local home brew store.

To find out how much alcohol you have in your root beer, you can use a hydrometer to measure the gravity of your soft drink both before and after fermentation.  The difference in gravity will tell you the alcohol content.  You can find more from beer brewing stores, and online.  This site gives a pretty good overview. 

Like I say, I haven't actually tried this, but if someone does and comes up with good results, let me know!  I might try this myself in the future and post a recipe on that.  

Help! My Root Beer Won't Carbonate!

There could be a few problems:

If the bottle got pressurized and you put it in the fridge, but when you drank it it wasn't pressurized, this could be because either the bottle had a loose seal (did it feel pressurized when you took it out of the fridge?)  Or it wasn't pressurized enough when you put it in the fridge. The bottle needs to feel very tight before you put it in the fridge.  For an example, feel an unopened bottle of pop from the store.  You can barely squeeze the bottle. If it is the bottle seal, you might need to get another bottle.  Plastic 2-liter bottles only last so many batches before the seal seems to break down.

If the bottle never gets pressurized, it is probably because the yeast died.  That could be because a) you put the yeast in the root beer while it was still too hot, which killed the yeast,  b) because the yeast didn't have enough nutrients, or c) the yeast needed to be activated before you use it.  So, make sure the root beer is at room temperature before you add the yeast.  Add a little bit of molasses to your root beer for nutrients (and a little taste), and that will help the yeast survive.  And if the yeast needed to be activated first, you can put the yeast in a little sugar water with some molasses for 30 minutes or an hour before you add it to the root beer (may want to check on this, I've never had to do this before). 

I've personally never had problem with my yeast not growning from lack of nutrients.  I just add my yeast straight to the root beer.  Sometimes it takes a little bit for the carbonation to really start going, but for me every time I've had a problem it has been because I added the yeast before the root beer had cooled down enough.

If none of the above suggestions work, you might want to talk to a beer brewer at a beer brewing store.  They know all about this stuff, and probably have lots of suggestions. 

 Contact us for any suggestions, or visit the forums .

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