| Problem |
Causes |
| Fermentation does not start |
- Inadequate amount of yeast pitched
- Wort too hot (yeast stunned/killed)
- Wort too cold (yeast dormant)
- Fermentation fine, but bucket not sealed (so you can't see bubbles in airlock)
- Fermentation already complete (look for ring of "crud" around inside of fermenter)
|
| Stuck fermentation |
- Not enough yeast pitched
- Inadequate aeration
- Wort temperature too low
- Yeast strain flocculated early (rousing yeast may help)
- Fermentation is finished, not stuck (take specific gravity to check)
|
| A puckering, tea-like quality; sometimes confused with bitterness (astringency) |
- X: steeped grains in too much water (over 3 quarts water per pound of grain)
- X: steeping water too hot (over 170 °F)
- AG: excessive volume of sparge water (collected wort less than SG 1.008 or above a pH of 5.8)
- AG: excessively hot sparge water (over 170 °F)
|
| Sour or tart beer |
- Contamination
- Tart ingredients (like raspberries or cranberries)
- AG: mash sat overnight and temperature dropped to 120 °F (or below)
|
| A buttery or butterscotch-like flavor or aroma (diacetyl) |
- Yeast did not absorb diacetyl (a diacetyl rest is required for some lager yeast strains)
- Contamination
- Racked beer too early
- Yeast strain
|
| Overly fruity aromas, especially banana (estery) |
- High fermentation temperatures
- Inadequate pitching rate
- Yeast strain (some British and Belgian ale strains are supposed to be very fruity)
|
| Chloraseptic-like or Band-aid-like aroma or flavor (phenolic) |
|
| Vinegar flavor or aroma (acetic) |
- Contamination, especially in conjunction with exposure to oxygen
|
| Wort darker than expected |
- X: concentrated wort boil
- X: scorching of malt extract (stir in thoroughly)
|
| Stuck mash |
- Running off wort too quickly
- Grains crushed too finely
- High percentage of wheat or rye
|
| Low extract efficiency |
- Crush too coarse
- Collecting wort too fast
- Collecting too little volume of wort per unit of grain
- Poor lauter tun design
- Water chemistry not conducive to good mash (check calcium levels first)
- pH outside of 5.2-5.6 range
|
| Overly high final gravity (FG) |
- Maybe the beer was supposed to have a high FG
- High percentage of specialty malt in recipe
- Yeast strain
- Any of causes listed under "stuck fermentation" (above)
|
| Chill haze |
- Use Irish moss (at rate of 1 tsp. per 5 gallons
- Boil too short or not vigorous enough
|
| Poor foam |
- Glassware dirty
- Weak fermentation
- Too little protein in wort (esp. when high amounts of adjunct are used)
- AG: overly-long rest at 122-131 °F
|
| Mold on surface of beer |
- It may be yeast, not mold (different yeast strains behave differently)
- Wort is exposed to oxygen, which encourages surface growths
|
| Bottle-conditioned beer is flat |
- Move bottles to warmer location for conditioning
- Give beer more time to condition
- Beer and priming sugar not adequately mixed in bottling bucket
- You forgot the priming sugar
- Not enough yeast left in beer to bottle condition (rarely happens)
|
| Bottle-conditioned beer is overcarbonated |
- Contamination
- Beer and priming sugar not adequately mixed in bottling bucket
- Too much priming sugar
|
| Beer's original gravity (OG) too low |
- X: wort and topping up water not mixed thoroughly
- AG: poor extract efficiency (see above)
|
| Cheesy aroma or flavor |
|
| Corn-like aroma or flavor (DMS) |
- Wort cooled too slowly when certain very pale malts used
- contamination
|
| Solvent-like or nail- polish aromas (higher alcohols, fusel oils) |
- Fermentation temperature too high
- Inadequate aeration
- High original gravity
|
| Skunk-like aroma |
- Beer exposed to light (especially due to bottling in clear or green bottles)
|
| Wet cardboard aromas and flavors (oxidation) |
- Beer exposed to oxygen during late fermentation or conditioning
|
| Sherry-like aromas or flavor (oxidation) |
- Beer exposed to oxygen during late fermentation or conditioning
- Long aging of high-alcohol beers (appropriate in some cases)
|
| Excessive sediment in bottle conditioned beer |
- Some sediment is always present
- Let beer fall clear before bottling
|
| Water, wort or beer on floor |
- Be sure all valves are closed before transferring liquid to a vessel
|
| Beer on ceiling |
- Fermentation lock clogged (use blow-off tube next time)
|
Resource Guide 
