Saturday was our local home-brew competition and Mike and I both entered beers. While one of the beers that I helped craft nearly won the popular choice category the other turned out to be a bit of a disaster.
One of the hardest elements when brewing at home for beginners is carbonation. Carbonation is critical to providing a great feel to the drinker. Too much carbonation and the beer feels harsh, acidic, and can even burn the throat a little. Not to mention making the drinker quite gassy as well. Too little carbonation can make the beer taste weak, stale, and flat.
Professional breweries have equipment where they can test the carbonation levels of their beer before kegging or bottling their beers. Since most breweries filter their beer of yeast before kegging or bottling their beer they don’t have to worry about an increase in carbonation from still active yeast in the bottle or keg.
Homebrewers don’t have easy access to this type of technology. Instead they are forced to “bottle condition” their beers to inject the CO2 into their beers. This is done by adding a “priming sugar’ to the already fermented beer and bottling unfiltered beer. Since the beer has not been filtered there is still live yeast in the bottle who feed on the added sugar and produce CO2 as a by-product. This is what creates the carbonation for home-brewed beers.
Yeast is a delicate and unpredictable creature. It requires careful temperature regulation to provide the proper effect.
If the bottled beer is placed in too cool an environment the yeast will be sluggish and thus under produce the carbonation desired in a beer. When opening an under carbonated beer you likely will not hear the signature “hiss” of a fresh bottle of beer. The beer will produce little or no head and will taste flat.
If the bottled beer is placed in too warm an environment the effect may be similar. The yeast will be too hot and as a result will be sluggish and again under produce yeast.
However, when the yeast find that Goldilocks zone they will eagerly eat any available sugar and produce carbonation.
If there are too few sugars for the yeast to eat there can again be a problem of too little carbonation. If there are too many sugars for the yeast there can be over carbonation.
Unlike under carbonation, over carbonation has a dramatic result. As you can see from the video above when the pressure in the bottle is released by opening the cap the reaction is impressive. There is a chain reaction where the CO2 that is in the beer is disturbed creating bubbles (which is what is desired in a beer is reasonable amounts) and those bubbles burst through the mouth of the bottle creating a miniature fountain of beer.
This is the result of having too much yeast with too much to eat in your bottle.
The video above was from a whiskey infused double IPA. I believe that my fault was rushing this beer a bit before it was ready to be bottled. I believe that the yeast had not yet finished fermenting the wort when I went to bottle and the addition of priming sugar and the sugars with the whiskey combined with an unseasonable warm snap meant that the yeast were given an ideal environment to go nuts and eat, reproduces, and give off CO2.
While this isn’t the ideal result the beer itself isn’t actually a waste. The carbonation will never decrease in the bottle meaning that each beer will be this carbonated but if you let the heady foam dissipate the remaining beer will still be drinkable and in my case quite tasty.
Needless to say there will soon be a second version of this beer, given the adequate time to ferment, and bottled conditioned in a cooler environment.
Just beware giving yeast all the desire. While they make beer what it is they are perfectly content to turn it into a piece of modern art.