Off Flavors In Beer

Front 1

ACETALDEHYDE

Back 1

•Tastes/Smells Like: Green apples, rotten-apples, freshly cut pumpkin.

•Possible Causes: Acetaldehyde is a naturally occurring chemical produced by yeast during fermentation.

•How to Avoid: Let the beer age and condition over
a couple months time.

Front 2

ALCOHOLIC

Back 2

• Tastes/Smells Like: Overpowering alcohol flavor, bitter, acetone, paint thinner, spicy, sharp, undesirable “hot” sensation in the throat.

• Possible Causes: Fusel alcohols such as propanol,
butanol, isobutanol, and isoamyl alcohol as well
as phenolic alcohols such as tyrosol.

• How to Avoid: Avoid fermenting at temperatures exceeding 80ºF.

Front 3

ASTRIGENT

Back 3

• Tastes/Smells Like: Tart, vinegary, tannin, drying, puckering sensation, may feel powdery or metallic in the mouth, like sucking on a grape skin or a tea bag.

• Possible Causes: Polyphenols or tannins are the
number one cause of such flavors.

• How to Avoid: Avoid grain that has been “over-milled”. When sparging, pay close attention to
the temperature and the amount of the water used.

Front 4

CHLOROPHENOL

Back 4

• Tastes/Smells Like: Plastic, Vinyl, Iodine.

• Possible Causes: Using chlorinated tap water to brew or rinse equipment.

• How to Avoid: Don’t use chlorinated water to brew or to rinse equipment that will come into contact with the beer.

Front 5

CIDERY

Back 5

• Tastes/Smells Like: Apple Cider, Wine, Acetaldehyde (apples).

• Possible Causes: Using too much corn or cane sugar is the most common cause for wine or cidery flavors.

• How to Avoid: Try cutting down on the amount of
corn or cane sugar being used.

Front 6

DIACETYL

Back 6

• Tastes/Smells Like: Butter, Rancid Butter, Butterscotch, Slickness in the mouth and tongue.

• Possible Causes: Diacetyl is naturally produced by all yeast during fermentation and is then "reabsorbed” by yeast cells.

• How to Avoid: Using medium flocculation yeast should give the yeast a good chance to absorb diacetyl.

Front 7

DIMETHYL SULFIDE (DMS)

Back 7

• Tastes/Smells Like: Cooked vegetables, especially
creamed corn, cabbage, tomato, shellfish/oyster-like
flavors

• Possible Causes: S-methyl methionine (SMM) is created during the malting process of grain and is later converted to DMS when heated.

• How to Avoid: It is very important to always
maintain a strong rolling boil for at least one hour.

Front 8

ESTERY/FRUITY

Back 8

• Tastes/Smells Like: Fruit, especially banana, to a lesser extent, pear, strawberry, raspberry, grapefruit

• Possible Causes: Strong fruity flavors or fruity flavors that are inappropriate for the style of beer are sometimes a result of under pitching or high fermentation temperatures.

• How to Avoid: Always pitch enough yeast for the gravity of your beer and oxygenate well. Keep fermentation temperatures under 75ºF when possible.

Front 9

GRASSY

Back 9

• Tastes/Smells Like: Freshly cut grass, musty

• Possible Causes: Are usually the result of grains or extract that have developed mold or bacteria prior to being used.

• How to Avoid: Always store grains or extract in a cool, dry, dark place.

Front 10

HUSKY/GRAINY

Back 10

• Tastes/Smells Like: Raw grain, dry, flavors comparable to astringency from tannins and/or oxidization.

• Possible Causes: Over milled grain can cause husky, grainy off flavors.

• How to Avoid: Avoid grain that has been shredded or crushed.

Front 11

MEDICINAL

Back 11

• Tastes/Smells Like: Cough syrup, mouthwash, Band-Aid™, smoke, clove-like (spicy).

• Possible Causes: Phenols can cause solvent, astringent, plastic and medicinal flavors.

• How to Avoid: Follow proper mashing and sparging
techniques and always follow the specific directions
for different sanitizers.

Front 12

METALLIC

Back 12

• Tastes/Smells Like: Metal, mainly iron, also described
as tasting like pennies or blood, Felt on the front of
the mouth and back of the throat.

• Possible Causes: Wort being boiled in unprocessed metals, mainly iron, but also aluminum, and steel (excluding stainless).

• How to Avoid: Use stainless steel pots and brewing
equipment (fittings, spoons, etc.).

Front 13

MOLDY

Back 13

• Tastes/Smells Like: Mold, mildew, musty, like mold
on bread.

• Possible Causes: is almost always the result of storing fermenting beer in a damp, dank area. Using extract or grain that has developed mold can impart moldy, mildewy flavors as well.

• How to Avoid: Always store your fermenter in a dry, dark place.

Front 14

OXIDATION

Back 14

• Tastes/Smells Like: Stale or old, wet cardboard, sherry, papery, pineapple, decaying vegetables, Increased bitterness, harshness.

• Possible Causes: Oxidation occurs when oxygen negatively reacts with the molecules in the wort or beer.

• How to Avoid: Oxidation is almost always a result of unnecessary splashing of fermented beer. When transferring beer from one vessel to the next, prevent splashing by transferring beer with tubing rather than pouring straight in.

Front 15

SALTY

Back 15

• Tastes/Smells Like: Salt, detected on the front sides of the tongue.

• Possible Causes: Adding too much gypsum or Epsom salt can create an overly salty beer.

• How to Avoid: Never add brewing salts to your water unless you know the original salt content of the water.

Front 16

SKUNKY

Back 16

• Tastes/Smells Like: Aroma of skunk, musty, can be similar to burned rubber or cat musk.

• Possible Causes: When hops are exposed to UV rays from sunlight or florescent lights, the alpha acids breakdown and react with the hydrogen sulfide that the yeast make.

• How to Avoid: When fermenting beer in a clear container, always keep it out of any direct sunlight or florescent lamps.

Front 17

SOAPY

Back 17

• Tastes/Smells Like: Soap, detergent, oily, fatty.

• Possible Causes: Keeping beer in the primary fermenter for a long time after fermentation is complete.

• How to Avoid: Transfer beer into a secondary if you plan on aging it in the fermenter for a long period of time.

Front 18

SOLVENT-LIKE

Back 18

• Tastes/Smells Like: Paint thinner, nail polish remover (acetone), harsh, sharp, in extreme cases can cause a burning sensation of tongue and throat, comparable to harsh alcohol or estery flavors.

• Possible Causes: Are usually due to a combination of very high fermentation temperature and oxidation of the beer.

• How to Avoid: Avoid fermenting at temperatures higher than the suggested range for the yeast being used. Avoid oxidation of beer.

Front 19

SULFUR/HYDROGEN SULFIDE

Back 19

• Tastes/Smells Like: Sulfur, burning match, rotten egg, raw sewage.

• Possible Causes: Is naturally produced by all yeast during fermentation.

• How to Avoid: During fermentation, the production of hydrogen sulfide is inevitable. Co2 will carry most of the hydrogen sulfide away.

Front 20

SOUR/ACIDIC

Back 20

• Tastes/Smells Like: Vinegary, acrid, felt on the sides of the tongue towards back of the mouth.

• Possible Causes: Extremely sour or vinegary flavors are almost always the result of a bacterial or wild yeast infection.

• How to Avoid: Make sure to thoroughly sanitize everything and anything that will be coming into contact with beer post boil.

Front 21

SWEET

Back 21

• Tastes/Smells Like: Overly sweet or sugary, sweet wort, cloyingly sweet.

• Possible Causes: A beer that tastes like unfermented wort is most likely the result of the yeast quitting prematurely.

• How to Avoid: Always use high quality yeast and make sure you are pitching the correct amount for the gravity of the wort or make a yeast starter.

Front 22

YEASTY

Back 22

• Tastes Like: Yeast, bready, can be harsh or slightly sulfur-like.

• Possible Causes: Unhealthy or mutated yeast can release “yeasty” flavors into beer.

• How to Avoid: If a beer such as a lager is going to be kept in a fermenter for a long period of time, using a secondary vessel is recommended.