Natural Carbonation

BACKGROUND

We have almost always bottle conditioned every batch we’ve turned out (even most of the kegged batches).  My personal opinion is that bottle conditioned and carbonated beer adds to the flavor depth and creates a better product.  Many of the Trappist Ales that consistently rank among the top beers in the world are bottle conditioned.  In a commercial setting this usually accomplished using wort from the newest batch currently being produced with a small pitch of viable yeast with very specific cell counts introduced.  It’s a finely tuned system that has evolved over a number of years (or generations) at the brewery where they know exactly what level of carbonation they will get.

On the home brewer scale we usually don’t have a fresh batch just finishing up around the time we bottle.  Even if we have brewed the same day it usually a different style and you wouldn’t want to mix beers would you?  To approximate this we can prime the batch with equivalent amounts of sugar to what would have been in that fresh wort.  What kind of sugar we use can affect the end result in different ways but nearly any sugar that yeast can eat will result in carbonation. 

PROCESS

Find a table online for the type of sugar you want to use, they’re available all over the place for all kinds of sugars, Google is your friend.  Common sugars are Dried Malt Extract (DME), Corn Sugar (sometimes called priming sugar), and even plain white table sugar (I think this is how the Mr. Beer system recommends you carbonate). 

Simply measure out the amount of sugar needed and boil it with 1-2 cups of water for a few minutes.  Always do this by weight if you have an accurate scale, one half cup is not always the same as another half cup.  What you see can vary by viewing angle and the compaction of the sugar can vary by scoop.  The point is to be as repeatable in your process as your equipment allows.  Place this in the bottom of your just sanitized bottling bucket (we usually sanitize right after cutting the heat to the priming sugar). 

Place the outlet of your hose in the very bottom of the bottling bucket to avoid aeration. I like to position it in a nearly tangential position to the wall of the bucket to create a good mixing effect (not too good as that will aerate).  From there start your siphon (sanitized of course), a racking cane and a tube full of clean water work but an auto siphon is very easy and quite inexpensive. Rack all of the beer from your fermenter into the bottling bucket being careful not to pick up too much of the yeast cake (some won’t hurt but keep it to a minimum). 

Cover the top of the bottling bucket to keep out free floating nasties that could cause an infection, saran wrap works fine here (sanitize it too).  Bottle and cap away, store the finished bottles at a good temperature for the yeast to work because if it’s too cold they will never carbonate the beer.

After you’re familiar with the common sugars you can experiment with anything you want.  There may be a little research to do to figure out the fermentable levels in special sugars but it shouldn’t be too difficult, and you can always just try it in a similar level to one of the common sugars.  Brown sugar, maple syrup, fruit juice, beet sugar, and probably anything else you can think of have been tried before with varying results. 

THINGS TO AVOID

1.  Amount of sugar to get the proper volume of CO2 - too little and your under carbonated, too much and you get bottle bombs

2.  Infection (Bacteria or Some other microbe) - Clean everything like you have OCD.  See the picture below of the broken bottle?  It was the only one in the batch that broke; all the other ones were carbonated at the correct level.

3.  Structural weakness in bottle likely due to damage or a manufacturing defect - This is the other possible cause of the broken bottle above.  Look them over for the obvious and discard ones with defects.

4.  Incomplete fermentation before bottling - Check out this video of a Saison we brewed.  It was great after 3 weeks, good for a few more weeks after that, and then it just became impossible to drink at all.  There was no way we added enough priming sugar to get to these levels it just wasn’t done when we put it in the bottles.

 

PROS

Insanely cheap start up equipment costs compared to kegging..  You need a bottling bucket, a racking cane, some hose, a bottle capper, caps, and bottles.  A capper comes with most starter kits and is pretty cheap to pick up on its own.  Bottles don’t cost much to purchase or come free with commercial beer (no twist off’s).

The method works for all styles.  As a bonus Abbey Ales, Russian Imperial Stouts, Barley Wines and other beers that take a much longer time to condition won’t be keeping a keg or tap tied up. 

CONS

Bottle Bombs

Inconsistent Results - depends entirely on your process and equipment

Additional Infection Exposure - If you aren’t careful

Additional Oxygen Exposure - If you aren’t careful

Higher Level of Effort Compared to Kegging

CONSIDERATIONS

May add some residual sweetness if using DME, can beneficial and sometimes it completely changes your beers flavor profile (especially in lighter and drier beers).  Think about trying corn sugar or dextrose if you want to avoid this. 

CONCLUSIONS

Try it a few different ways.  Set up an experiment where you brew a super simple 5 gallon extract batch and bottle each gallon with a different approach try out.  Remember to check the volumes of CO2 for the style and try to keep the same volumes using:

            -DME

            -Corn Sugar

            -White Table Sugar

           

Then grab some of those carbonation tabs for a gallon and maybe use too little of one of the three above for the last gallon (don’t overdo it as bottle bombs are dangerous and an absolute mess to clean up).  Figure out what you like the best and make your beer that way, there is no right answer just personal preference.

Additional Notes on natural carbonation and conditioning in kegs:

We have done this several times and really can’t form an opinion on it yet.  Good thing is it doesn’t require a dedicated line off your CO2 tank for carbonation.  This is quite useful if your tank is in the fridge with the kegs on tap like mine is.  It is a bit slower than force carbonation.  You can’t just put in the same amount of sugar that you would for bottling, your beer will be way over carbonated (strike this one up to personal experience).  Take all that for what it’s worth.