After a hard days work, you sit down, crack open a nice home brewed Pale Ale and while you reach for your glass, foam starts to creep out of the bottle or even worse, it gushes out uncontrollably. It’s not that uncommon and in order to minimise and prevent it, it helps to understand what’s happening in the bottle in the first place.
Since most home brewers don’t pump CO2 into their beer to carbonate it, we simply give the remaining yeast in the beer a little food and it takes care of the work for us. Adding a little dextrose, table sugar or honey will do the trick, and contrary to popular thought, the flavour impact is not noticeable.
So why is my beer foaming over?
Good question, and there are various common causes.
- Your beer was bottled too early and was still fermenting in the bottle, creating excessive pressure
- Infection: Your beer may have picked up a bacteria when transferring into the bottles
- Too much sugar/honey added
- Heat. Warmer liquids cannot absorb as much gases as colder ones. So, if you open a warm home brew, chances are that the gases in the bottle will be pushed out of the beer itself as fast as possible
What can I do?
First of all, make sure any beer you open was in the fridge for 2 days. The cold beer needs time to absorb the CO2, so don’t rush it. Some brewers recommend putting your beer in the fridge for a week or two, but hey, sometimes you just can’t wait that long!
Second, pay closer attention to cleaning and disinfecting when brewing and bottling. Everything that comes into contact with your beer after boiling it, needs to be properly cleaned. Everything! In our experience, most foaming problems are related to insufficient cleaning, especially when using old bottles. The best trick to make sure you got rid of any bacteria, is to put your cleaned empty bottles into a preheated oven (200°C) and let them sit for about 15 minutes.
Beyond that, don’t rush fermentation. Some beers will be done in two weeks and some need longer. Most kits write very short brewing times in their instructions, but any good beer needs time to develop. Good things are best not rushed!