When should you aerate your beer?
There are times when introducing oxygen into your beer is essential to successful brewing but there are also times that doing so can have unwanted effects on your beer.
A key period in the brewing process where we do not want to introduce oxygen into our beer is when the wort is hot. This is called ‘hot side aeration’. Vigorous stirring of your mash or allowing the wort to free fall from your mash-tun to your boil pot are to key things we want to avoid. Introducing oxygen into the wort when its hot is unwanted as it can oxidize the polyphenols (also known as tannins) which lead directly to the darkening of the wort. The oxidation of polyphenols as well as the melanoidins in the wort can also contribute to stale flavours in your beer.
So when do we want to add oxygen into the mix?? The only time in the entire life of the beer where we want to add oxygen is after the wort has cooled, but before fermentation. Oxygen is key to the successful reproduction of yeast cells. The time after you add yeast to your wort until it is actively bubbling away is when the yeast cells are reproducing and oxygen is essential during this period.
So, how do we aerate our wort? There are several ways one could do this, but two or three possibilities come to mind.
Personally, I let the wort free fall from counter height into the fermenter. This allows the wort to splash and mix in the fermenter and will under most circumstances introduce enough oxygen into the wort for successful fermentation. I have used this method for 2 years and have never had a problem.
Another method that some people use is an aeration stone and oxygen tank. I have never done this but most homebrew shops carry a 2 micron aeration stone. When this is hooked up to a tank of oxygen via a hose and inline air filter the wort can apparently be totally oxygenated in as little as a minute.
Lastly, you could stir and splash around your wort in the fermenter with a sanitized spoon or if you are feeling especially strong you could pick up your fermenter and shake it around. Either way, you’ll probably need to do it for around 10 minutes.
So that’t it. Oxygen is essential to the beer making process, but it can also have unwanted effects at certain points in the brewing process. This is a fairly easy, yet important part of home brewing to think about and keep a handle on.
Happy brewing!!
This post is mirrored on the Homebrew Korea Community Forums.
