To be a good brewer and judge of other beers you need to be able to recognize off flavors in your beer and be able to know where and why these off flavors are there. There are many flavors in beer that the common drinker would think were “off” or out of place might actually flavors that are supposed to be there for certain beer styles. I’m going to list a couple common off flavors that you might find in your beer and some ways that you can avoid them in the first place.
Astringency is a similar flavor to the pallet as bitterness but it has more of the effect of sharp bitterness that isn’t enjoyable. I have heard it compared to sucking on a tea bag. This can be caused by getting to many tannins into your beer. These tannins can be extracted from your grains in many ways. One is steeping your grains too long. An extra-long steep an increase the PH of your beer and cause more tannins to be released from the grains. Also sparging your grains with water that is too hot can cause your beer to get that Astringent flavor.
This is another very common off flavor that tastes like it sounds, Like metal. It can present like a mouth full of pennies or just maybe a little irony but not in the ironic sense. This can be caused by actually dissolving metals into your brew by using a non stainless steel pot or an aluminum pot that has been deeply scored or scratched to remove its protective oxide layer. Oxidation in your beer can also cause a metallic flavor depending on what compounds in your beer are oxidized.
Yes this flavor can actually be caused by soap from not rinsing glasses or equipment thoroughly but that usually isn’t the case. Most of the time when you get soapy flavors it is a result of something gone awry in the fermentation. Usually the culprit is leaving a finished fermentation in the fermenter for too long. The length of time is entirely dependent on the style of the beer. But if you go too much longer than required you start to run the risk of getting these off flavors.
These are just a few of many ways to trouble shoot and recognize some off flavors in home brews and even commercial beers. Even the pros make mistakes from time to time. Knowing what you’re tasting will help you become a better brewer and a better drinker. Hopefully this will shed a little light on some beers you have made in the past or will be making in the future. Happy drinking.