Following on from my posts on making a yeast starter, and brewing my Belgian Strong Ale, I’ve turned my attentions to my priming practices. I have bottled all of my previous nine brews. All nine brews have been transferred straight from my fermentation vessel (i.e. straight off the yeast cake, and into bottles primed with cane sugar. This is where I admit to the fact that I have been adding priming sugars to each bottle individually, 1/4 tsp for 330ml bottles and 1/2 tsp for 500ml bottles. It has worked fine for me, but I want to improve my practices and my beer. This also means that I will be transferring all my future beers off the yeast cake (trub) before priming and racking, a practice which should further improve the quality of my beer.
This post is to document how I have calculated my priming addition and how I plan to use it, and not really a post about the relationship between yeast and sugar and practices such as re-yeasting a beer before bottling, nor is it a post on the basics of getting your beer into a bottle.
As with my yeast starter, I am using some instructions kindly provided by Dominic Driscoll from the Thornbridge Brewery. He visited our local homebrew group back in January and talked us through the key points to consider when brewing a high gravity beer. The instructions apply to any beer, not just those of high gravity. I have brewed an 8% Belgian Golden Strong Ale and I want it to be carbonated in a similar way to Duvel, and I found information on this beer in Stan Hieronymus‘s book – ‘Brew Like a Monk‘.
The first step is to appreciate that there are two ways of measuring CO2:
- volumes (how brewers think of CO2). One volume of CO2 is equivalent to 1.96g/l.
- grams (how brewers calculate CO2).
Here are the components of the equation you use to calculate how much sugar to add before bottling:
A). Beer volume to be packaged (beer volume to be bottled plus any liquid you use to dissolve the priming sugars).
B). CO2 produced per gram of sugar (0.46 grams).
C). Beer CO2 prior to bottling (this is temperature dependent, see Fig. i).
D). Target CO2 level in the bottle post conditioning (typical levels for different beer styles can be found online or in homebrew books – see links below).
E). The required CO2 to produce in a bottle. The formula to calculate the required CO2 to produce in the bottle (E) is:
D – C = E
Then use your value for E to calculate the amount of sugar required:
(A * E) / B
…You must make correct sugar calculations, so you don’t end up with a warm room full of bombs – Stan Hieronymus’
The quote above is apt. I emailed my calculations to Dominic to check that I had applied the maths correctly. I had of course made a couple of errors, but the worst being my target of 4.25 volumes of CO2 (8.5g/l), based on my reading that Duvel has this amount in their bottles at the end of bottle-conditioning. I was advised that this would end in a mess, unless I had enough Duvel bottles to use (which I don’t). I was aware that reusing bottles, and more importantly reusing bottles not intended to be used as containers for beers with 3 volumes or above, was a recipe for disaster. Just to be on the safe side, I have managed to source plenty of 330ml bottles intended to house Belgian beer. My target of 3 volumes of CO2 should give me a nice fizzy beer in keeping with the style guidelines.
Just to add, for anyone who read that last sentence as a bull would view a red flag, I am brewing a beer for me to enjoy, but also to be judged in a BJCP competition, which makes the beers carbonation as relevant as the malt bill or the noble hops I used, or the yeast (you get my point). Brewing within style guidelines does not mean I left my creativity at the door. Just to balance things up, my previous nine brews have all been ‘rule’ breakers….unintentionally.
If you are already brewing then you will either have your own way of priming or more likely to be using one of the many calculators within brewing software and resources on-line which will work all this out for you, but notice that most have disclaimers advising you to apply common sense where sugar additions appear to be high. For this reason and for fun, I wanted to learn how to calculate this myself.
Other useful sources of information:
- Brew Like a Monk (Chapter 9: Bottling).
- TastyBrew – Bottle Priming Calculator There is a calculator, but also a useful drop-down list of ‘Average CO2 volumes listed by BJCP style’ (however BJCP do not list CO2 volumes on their site).
- “Brew By The Numbers – Add Up What’s in Your Beer,” by Michael Hall in Zymurgy magazine, Vol. 18 No. 2, (Summer 1995): 54:61
- Use the above, or other sources to guide you, but carbonate the beer to where you want it!