Troubleshooting Off Flavors
in Your Beer

Troubleshooting the off flavors that get into your beer is an art as well as a science. With a little experience and a good reference, you will learn to refine your sanitization and processes to prevent these unwanted sanitization flavors. Although processes and sanitization are often the cause, there are many subtle causes that must be taken into consideration once you have eliminated the obvious. Many are extremely nasty once they get into your brewery so it is important to find the causes and eliminate them immediately.

Once you learn to evaluate your beer, you'll begin to notice aromas and flavors you never noticed before. Some off flavors are acceptable in certain styles, ie. diacetyl is acceptable in Scottish ales, but not in most lagers or other clean beers. Listed below are links for troubleshooting most of the off flavors you may encounter when homebrewing. Each will discuss causes and preventions of the various off flavors you may find.

ACETALDEHYDE is perceived as green apples in both aromas and flavors. Although it is noticed in a few commercial examples, for the most part it is considered a flaw. To learn more about what causes it and how to prevent it, click here.

DMS-Dimethyl Sulfide is a volatile sulfur based compound which if noticed, will be perceived as cooked can corn, or possibly celery. To learn how it is produced and the easiest fix, click here.

SKUNKED-or LIGHT STRUCK beer is a fault caused by the reaction of isomerized alpha acids from hops (isohumulone) with riboflavin in the presence of light. To learn about how to prevent this unwanted flavor, click here.

METALLIC off flavors are perceived as the taste of a rusty nail, or coin-like, tinny and blood-like. To see some of the causes and preventions of metallic flavors in your beer, click here.

OXIDIZED or STALE flavors in beer are perceived as sherry-like, stale bread, wet cardboard and paper. It is not always considered a fault though. To find out more about stale flavors in your beer, click here.

SOUR or ACETIC flavors are perceived as sour, vinegar-like, and tart on the sides of your tongue. The primary causes of sourness in beers are bacterial. To learn how to prevent these sour flavors, click here.

VEGETAL flavors in beer often manifest themselves as cooked cabbage, broccoli, or corn. To learn about the causes and prevention of vegetal flavors and aromas in your beer, click here.

ALCOHOL FLAVORS are usually caused by fermenting at too high of a temperature which causes the yeast to produce too many fusel alcohols. These are perceived as being hot and spicy. To learn more about alcohol related off flavors in beer, click here.

ESTERS For some beers, such as German hefeweizens, fruity esters define the style. But for other beers, like clean lagers, ester formation is not wanted and is considered a flaw. You as the brewer have some control of the amount and type of esters in your beer. To learn all about esters, and some ways you can control their production, click here.

PHENOLS Phenolic flavors and aromas in beer are most often described as clovey, spicey, smokey, band-aid-like, or medicinal. Except in a few beer styles where some of these flavors are considered appropriate, these compounds are for the most part considered a flaw. To find out what can cause phenolic flavors and aromas in your beer and how to prevent them, click here.

FATTY ACIDS Fatty acid concentrations are initially low in wort but increase as fermentation and maturation progresses. These medium-chain acids are a normal constituent of your beer. They contribute to the characteristic flavors you associate with some beers. To learn about the fatty acids that can cause off flavors, click here.

DIACETYL Diacetyl is a normal byproduct in the fermentation process of beer. There are varying methods of reducing or eliminating it in the final product, but it is always produced. To learn all about diacetyl, how to detect it and prevent it, click here.

ASTRINGENCY Astringency is perceived as a dry grainy, mouth-puckering, tannic sensation (think of sucking on a wet tea-bag). Although astringent flavors may be caused by bacterial contamination, it is usually the result of processing. To learn more about astringency, click here.

Although off-flavors can be frustrating, learning the causes and cures will help you brew better beer next time. It happens to the best brewers, that's how they get to be the best brewers, by learning from their mistakes.

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