The only bad thing about home brewing: to pour your heart and soul into a batch, only to discover that there are weird flavors in your beer. Let’s take a look at some of the culprits that cause these strange flavors, and ways to stop them from wreaking havoc on your beer.
1. Acetaldehyde – The green apple flavor.
Cause: Acetaldehyde is a naturally occurring compound during the fermentation of yeast. It’s usually converted to ethanol alcohol during the fermentation process. Some yeast strains will produce more Acetaldehyde than others, but it usually means your beer is under conditioned.
Solution: Luckily, this problem is easy to fix. Acetaldehyde usually will take care of itself after some more conditioning. Aging your beer is an important part of home brewing. If you detect apples in your beer, just let it sit a couple weeks longer.
2. Chlorophenol – The plastic or medicinal taste.
Cause: The most common reason for chlorophenol to be present in beer is using chlorinated water during the cleaning process. It’s also possible that ingredients bought for brewing were 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 just make sure that you never use chlorinated water at any point in the brewing process. This might seem obvious, but many people use tap water to clean equipment, and tap water may have chlorine.
3. Diacetyl – The bad butter flavor.
Cause: Diacetyl is another by product of the fermentation process. During healthy fermentation, yeast will break down the diacetyl. However, mutated yeast can cause serious problems. Some yeast will lose the ability to metabolize diacetyl, and leave the buttery flavor in your beer.
Solution: In most cases, just allow your beer enough time to age, so that the yeast can absorb all of the diacetyl. But if your yeast is mutated, this problem will not go away with time. Be sure to always use the healthiest, and highest quality yeast you can find in order to avoid this problem.
4. Dimethyl Sulfide – Like vegetables in your beer.
Cause: All malts have a chemical in them 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 taste.
Solution: Luckily, most of this DMS is evaporated during the boiling process. To ensure that higher concentrations aren’t present in your beer, be sure to maintain a rolling boiling during the brewing process. Some brewers will boil for 90 minutes to ensure that most of the DMS is evaporated.
5. Atringency – Tastes tart, vinagery, or metallic.
Cause: Atringency in beer can be caused by many factors, but it’s usually a result of tannins being released from your grains. Tannins are found in all grain skins, and they are released when grains are steeped at too high of temperatures, steeped too long, or when they are milled too finely.
Solution: Be sure to never mill or crush grains too much. Always steep your grains for the correct amount of time, at the correct temperatures, and never boil your grains. These preventative measure will ensure your beer tastes great.