Home brewing: the 5 scary things that could lurk in your beer

The only downside to home brewing: pouring your heart and soul into a batch, only to find that there are strange flavors in your beer. Let’s take a look at some of the culprits that cause these strange flavors and ways to prevent them from wreaking havoc on your beer.

1. Acetaldehyde: the taste of green apple.

Cause: Acetaldehyde is a natural compound during yeast fermentation. It is usually converted to ethanol alcohol during the fermentation process. Some yeast strains will produce more acetaldehyde than others, but it generally means your beer is not conditioned.

Solution: Fortunately, this problem is easy to fix. Acetaldehyde will generally heal on its own after a little more conditioning. Aging beer is an important part of home brewing. If you detect apples in your beer, let it sit for a couple more weeks.

2. Chlorophenol – The plastic or medicinal flavor.

Cause: The most common reason chlorophenol is present in beer is the use of chlorinated water during the cleaning process. Ingredients purchased for brewing may also have been stored in an area that may have exposed them to chlorine, although this is less common.

Solution: The best way to avoid this is to simply make sure not to use chlorinated water at any point in the brewing process. This may seem obvious, but many people use tap water to clean equipment, and tap water can contain chlorine.

3. Diacetyl: the bad buttery taste.

Cause: Diacetyl is another by-product of the fermentation process. During healthy fermentation, the yeast will break down the diacetyl. However, mutated yeast can cause serious problems. Some yeasts will lose the ability to metabolize diacetyl and leave a buttery taste in beer.

Solution: In most cases, allow the beer to age long enough for the yeast to absorb all of the diacetyl. But if your yeast is mutated, this problem will not go away over time. Make sure to always use the healthiest and highest quality yeast you can find to avoid this problem.

4. Dimethyl Sulfide: Like the vegetables in your beer.

Cause: All malts contain a chemical called S-methyl methionine or SMM. During the mashing and heating process, this chemical is converted to dimethyl sulfide or DMS. This is the chemical that causes the vegetable flavor.

Solution: Fortunately, most of this DMS evaporates during the boiling process. To ensure that there are no higher concentrations in your beer, be sure to maintain a constant boil throughout the brewing process. Some brewers boil for 90 minutes to make sure most of the DMS evaporates.

5. Attringency: it tastes like cake, wine or metallic.

Cause: Atringency in beer can be caused by many factors, but is generally the result of the release of tannins from the grains. Tannins are found in all bean skins and are released when beans are soaked at too high temperatures, soaked too long, or when they are ground too finely.

Solution: Make sure you never grind or over-mash the beans. Always let the beans sit for the correct time, at the correct temperatures, and never boil the beans. These preventative measures will ensure that your beer tastes great.