It’s easy to get lost in the thousands of home brewing terms out there. One of the first terms that confused me was aeration and oxidation. This article will address the differences between the two, when you need them and the potential pitfalls of oxidation.
Aeration, by definition, is the process in which air is circulated through or mixed with a substance. Aeration during homebrewing is used specifically when the wort has been cooled to a sufficient temperature (under 80° F) and the yeast is ready to be pitched. Before you throw those yeastie beasties in there, you need to aerate the wort (by mixing with a spoon) in order to bring sufficient enough oxygen in the wort in order for the yeast to grow.
Oxidation is the combination of a substance with oxygen. Oxidation is bad for beer. Oxidation can occur during fermentation or while racking (transferring) your beer from one container to another. It can also occur if there is too much splashing while you move your beer to the bottling bucket or your secondary fermentor.
Why is oxidation bad?
Oxidation can produce staling of the beer. Staling of the beer can have a major effect on the flavor, resulting in a cardboard like taste. I have seen some crazy flavors for beer, like strawberry-chocolate stout or fruitcake flavored dubbel but I doubt anyone would enjoy a Cardboard Oatmeal Stout.