A
Acetaldehyde
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Alcoholic
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Acetaldehyde
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
- Green apples
Yes, at low
levels
L/S/P American
Lagers (from yeast
character is
optional)
- Premature
removal from
yeast
- Allow ferment to
complete
- Premature
flocculation
- Good yeast strain
-Oxygen
depletion
- Aerate wort
prepitching
- Bacterial
spoilage
- Practice good
sanitation
- Oxidation
- Beer handling to
avoid O2 contact
- Grassy
- can taste and
smell acetic
(vinegar)
/ cidery
- long lagering will
reduce
Troubleshooting Off-flavors- Alcoholic
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it caused?
How can it avoided/
controlled?
- Hot, Spicy
Yes
Stronger ales and
lagers
- High amount of
fermentable sugars
- avoid large
amounts of sugars
- High fermentation
temperature
- Lower
fermentation
temperature
- Low mash
temperature
- Increase mash
temperature
- Underpitching
- Pitch sufficient
yeast quantity
- Low O2 or FAN
- Aerate wort prior
to piching
- Yeast strain
- Healthy Yeast
- Vinous aroma
- A warming,
prickling
sensation in the
mouth and throat
- Age
A
Astringent
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Bitterness
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Astringent
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
- Dry, Mouth
puckering,
unpleasant
No
N/A
- Extraction of
tannins
(overcrushing,
oversparging)
- Don’t overcrush
- Alkaline mash
or runoff water
- Watch mash/runoff
pH
- excessive
hopping
- Reduce hop
immersion times
- Polyphenols
from acetobacter
- Practice good
sanitation
- Spices
- Reduce spice
additions
- in mouthfeel
and aftertaste
- tannic, tart
sensation
reminiscent of
grape skins
- Keep sparge temp
low
Troubleshooting Off-flavors- Bitterness
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
- will be tasted on
the back of the
tongue and the
roof of the mouth
Yes
IPA’s
- High AAU
hops
- Use hops with lower
alpha acids
- Lengthy hops
times
- Reduce hop boil times
- fermentation
temperature
- Higher temperature
and quick fermentation
decrease bitterness
Pales ales
English Bitters
- filtration reduces
bitterness
A
Buttery
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Cardboard
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Buttery
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
- in Aroma, Flavor
and Mouthfeel
Yes
Scotch Ales
Bitters
Dry Stouts
Czech Pils
Oktoberfest
Diacetyl:
- Premature
racking/ fining/
lagering
- Allow ferment to
complete
- Low
fermentation
temperature
- Higher temperature
primary fermentation
- High: Butter,
Butterscotch
- Mutant yeast
- Good pure yeast
strain
- Mouthfeel, a
slickness on the
palate
- Lactic acid
bacteria
(Pediococcus)
- Diacetyl
- Low: Nutty,
caramel
- Practice good
sanitation
- Long periods of
wort cooling
- Quick wort chilling
- Underpitching
of yeast
- Adequate yeast
starter amount
-Too long an acid
rest in mash
- Shorter acid rest in
mash
Troubleshooting Off-flavors- Cardboard
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
Oxidation
No
N/A
- Aeration of hot
wort
- Quiet transfer of
beer when siphoning
or transferring
- in Aroma and
Flavor
Initial:
Cardboard,
paper, wet paper,
stale bread
crumbs,
pineapple
Later: sherry-like,
leathery, woodsy
- Aeration of beer
during bottling
- excessive age
- Serve beer in
appropriate amount of
time
- High storage
temperatures
-Cool (<55F) storage
temps
- Adding tap
water to finished
without boiling
-Add only boiled/
chilled water to beer
after primary
fermentation
-excessive head
space in bottle
-Proper head space in
bottle
A
Cloudiness
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Cooked Corn
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Cloudiness
Describe/Discuss
Ever
Appropriate?
If so, what
styles?
How is it caused?
How can it avoided/
controlled?
- in Appearance
Yes
Wheat Beers,
Lambics,
American Wheat
Chill haze:
- Insufficent
conversion time
- Longer mash
Permanent Haze:
- excessive or high
temperature sparge
- Use clearing agents
- Cloudy, hazy
- Use protein rest
- Use filtration
- Reduce sparge
temps
- Bacterial/ wild
yeast contamination
- Practice good
sanitation
- Poor, wrong, weak
or mutated yeast
strains
- Use well-flocculating
yeast strain
- wheat malt
Troubleshooting Off-flavors- Cooked Corn
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
- DMS (dimethyl
sulfide)
Yes
American Lagers
Cream Ales
- Poor sanitation
- Practice good
sanitation
- Covered boil
- Open, rolling boil for
an hour or more
- in Aroma and
Flavor
- Vegetal
(Sweet cooked
corn, celery,
cabbage, parsnips)
- Shellfish or
oyster-like in
higher amount
- Precursor
S-methylmethionine (SMM)
occurs naturally in
Pale malt, turns in
DMS with heat,
evaporates
- not boiling wort
for at least an
hour
- contaminated
yeast
- Fresh yeast culture
- Over-sparging
with water below
160 degrees
- Proper sparging
- Overnight
cooling
- Quick wort cooling
- Underpitching
- high pitching rates
A
Fruitness
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Light Body
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Fruitness
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
- Esters
Yes
Ales
- Alcohols
combining with
acids at higher
temperature.
(Ethyl acetate,
Isoamyl acetate,
Ethyl Hexanoate)
- in Aroma and
Flavor
American Dark
Lagers (very light)
- Banana, apple,
citrus, strawberry,
black currant,
grapefruit,
raspberry and
pear, etc
Dopplebock (in
dark versions)
Eisbock
How can it avoided/
controlled?
- Yeast strain
used
- Choose a different
yeast
- Higher
fermentation
temperatures
- Lower fermentation
temperature
(Ales around 60 F,
Lagers around 50 F)
- High-gravity
wort
- Lower gravity wort
How can it avoided/
controlled?
Troubleshooting Off-flavors- Light Body
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it caused?
- Watery
Yes
American Light
lagers
- Lack of dextrins
- Weak
- Poor quality malt
- Use quality malt
- Large percentage
of sugar
- Keep percentage of
sugars small
- Low-temperature
saccharification
rest
- High-temperature
saccharification rest
Lambics
- in Flavor and
Mouthfeel
- Use dextrin, crystal
or wheat malt.
A
Grassy
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Husky-Grainy
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Grassy
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it caused?
How can it avoided/
controlled?
- in Aroma and
Flavor
Yes, as a hop
character
American Pale Ale
English IPA
America IPA
Imperial IPA
- Poor quality malt
- Good, fresh malt
stored under airtight
conditions
- Fresh-cut grass
- New-mown hay
- Poor storage of
malt
- Cracking grains
well in advance of
brewing
- Cracking grains
shortly before brewing
- Some English
and American hop
varieties
- Choose a different
hop
- Dry Hopping
- Oxidation of
alcohols creating
hexanal and
heptanal
Troubleshooting Off-flavors- Husky-Grainy
Describe/Discuss
Ever
Appropriate?
If so, what
styles?
How is it caused?
How can it avoided/
controlled?
- in Aroma and
Flavor
No-Husky
None
- Excessive grain
crushing
- Proper crush
Yes-Grainy
Light Lagers
Pilsners
N. German Alt
Brown Porter
Robust Porter
Dry Stout
Wheat beers
- High Sparge
temperature
- Lautering
temperatures
between 164-170°
- Excessive sparging
- Proper sparge
amounts
- High pH during
sparging (above 6.0)
- Monitoring pH of
runoff (keep pH
below 6)
- High mineral
content in water
- Water appropriate
to style
- Boiling grains
- Steeping adjunct
grains below 170
degrees
- Improper decoction
mashing
- Temp. controlled or
infusion mash
- Cereal
- Grainy
- Huskiness
- Spent grains
Husky
- Tannins from
grain husks
Grainy
- starches in
barley malt
A
Low Head
Retention
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Phenolic
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Low Head Retention
Describe/Discuss
Ever
Appropriate?
If so, what
styles?
How is it caused?
How can it avoided/
controlled?
- Flat
Yes
Lambics
- inadequate
protein rest
- Adequate protein rest
- insufficient or
deteriorated hops
- Use hops with high
alpha acids
- Dirty/oily/soapy
glasses
- Use clean well-rinsed
glasses
- low-temperature
saccharification
rest
- High-temperature
saccharification rest
-not using a onehour boil
- good one hour (open)
rolling boil (to extract the
isohumulones)
- in Appearance
and Mouthfeel
High Alcohol
Beers
- Use cara-pils, crystal
malt, malto-dextrin, wheat
malts
- Lower alcohol by
lowering the grist bill
Troubleshooting Off-flavors- Phenolic
Describe/Discuss
Ever
Appropriate?
If so, what
styles?
How is it caused?
How can it avoided/
controlled?
- in Aroma and
Flavor
Yes
Some Belgians
beers
- Wild yeast
- Use pure yeast strains
- Improper
sanitation
- Practice good
sanitation
- Some malt types
- Use “clean” malt
- Some yeast strains
- Use yeast less prone
to phenolic production
- Chlorophenols in
water
- filter tap water
- Improper rinse of
chlorine sanitizers
- Use non- chlorine
sanitizers
- Oversparging;
sparging above pH
6.0; sparging above
170 degrees
- Proper sparging while
monitoring temperature
and pH
- Band-aid
- Clove-like
- Smoky
Chlorophenolics
- Plastic
- Medicinal
Smoke beers
Some Wheat
beer
A
Lightstruck
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Musty
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Lightstruck
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
- in Aroma and
Flavor
No
None
- Beer stored in
clear or green
glass bottles
- Store beer in Brown
bottles
- Beer exposed
to direct sunlight
or ultraviolet
light
- Keep beer
- Skunky
- Mercaptan
- Sulfidic (H2S)
- Ultraviolet light
reacting with
isomerized alpha
acids
Troubleshooting Off-flavors- Musty
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
Oxidation of malt
compounds
Yes
Bière de Garde
- Aeration of hot
wort
- Quietly transfer of
wort/beer when
siphoning or
transferring
- in Aroma and
Flavor
- Musty
- Cellar-like
- Earthy
- Aeration of beer
during bottling
A
Sherry-like
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Sourness
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Sherry-like
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
Oxidation
Yes
Barleywines
- Oxidative
yeasts acting on
higher alcohol
beers creates
aldehydes (ie.
trans-2-nonenal)
- Use different yeast
strain
English Old Ales
- Sherry
- Vinous
- Leather
- Woodsy
- Wine-like
- Paper-like
- Old
- Create less alcohol
by lowering grist bill
- Serve beer younger
- Ferment cooler
- Accompanied
by hazelnut or
almond notes
Troubleshooting Off-flavors- Sourness
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it caused?
How can it avoided/
controlled?
basic taste
sensation
Yes
Witbier
Lambics
Flanders Ale
Berliner Weisse
Poor sanitation
- Practice good
sanitation
- in Aroma and
Flavor
-perceived on
sides on the
tongue
- Tart
- Sour
- vinegar-like
aroma
(optional
sourness)
American Wheat
or Rye, Dry Stout,
Witbier and
Saison
Acid-creating
Bacteria’s
(Lactobacillus,
Pediococcus,
Acetobacter)
- Some yeast
strains
- Choose a different
yeast
- Excessive acid
rest
- Shorter acid rest
- Mashing too long
- Mashing for less
than two hours
- Scratched plastic
fermenter
- Use glass carboy or
stainless steel
fermenters
- Storage at warm
temperatures
- Cool (<55 degree)
storage
A
Solvent-like
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Sulfury/
Yeasty
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Solvent-like
Describe/Discuss
Ever
Appropriate?
If so, what
styles?
How is it caused?
How can it avoided/
controlled?
- in Aroma and
Flavor
No
None
- Wild yeast
contamination
- Good sanitation of
equipment
- Pungent, acrid
aroma
- High fermentation
temperatures
- Cooler fermentation
temperatures
- Harsh, burning
sensation on the
tongue, back of
the throat
- Lack of oxygen
- Proper wort
oxygenation
- Underpitching
- Pitch sufficient
yeast quantity
- Non-food grade
plastic equipment
- only food-grade
plastic used
- Acetone-like
- Lacquer-thinner
like
- Turpentine
- Ethyl acetate
Troubleshooting Off-flavors- Sulfury/Yeasty
Describe/Discuss
Ever
Appropriate?
If so, what
styles?
How is it caused?
How can it avoided/
controlled?
- in Aroma and
Flavor
No
None
- Bacterial
contamination
- Practice good
sanitation
- Rotten eggs
- Yeasty
- Meaty
- Wild yeasts
- Yeast strain
- Good yeast strain
Sulfitic- SO2
Struck match
-- old beer (yeast
autolysis)
- Racking off
sediment
Sulfidic
Hydrogen sulfide
(H2S)
- Rapid temperature
changes to
fermenting wort
- Cooling lagers no
more than 5 degrees
per day
Low level: Garlic,
onion
High level: burnt
rubber, shrimplike
A
Sweet
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
xxx
Minnesota Home Brewers Association: Sean P. Hewitt
1/26/06
Troubleshooting Off-flavors- Sweet
Describe/Discuss
Ever
Appropriate?
If so, what styles?
How is it caused?
How can it avoided/
controlled?
- Basic taste
sensation
Yes
- High levels
desirable in most
strong ales and
lagers
- Quick
flocculating or Low
attenuating yeast
strain
- Yeast strain with
good attenuation
- Low levels in
American light
lagers and lambics
- High-temperature
mash
- Low-temperature
mash
- Addition of
dextrin malt, maltodextrin, crystal
malt
- Reduce the grain
- Addition of
lactose or licorice
- Reduce the amount
- Poor yeast health
- Add yeast
nutrients, Proper
wort oxygenation
- Premature
lagering
- Lagering, after
primary fermentation
- taste perceived
primarily at the
tip of the tongue
- Due to the
presence of
reducing sugars
- Sugary
- Syrupy
Troubleshooting Off-flavors- x
Describe/Discuss
-
Ever
Appropriate?
If so, what styles?
How is it
caused?
How can it avoided/
controlled?
-
-