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Davs Off Flavors > Off Flavors > Flashcards

Off Flavors Flashcards

1
Q

Normally reduced to ethanol during fermentation

OXIDATION of finished beer may reverse this

A

Acetaldehyde

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2
Q

Present in green beer

A

Acetaldehyde

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3
Q

Bacterial spoilage Zymomonas or Acetobacter

A

Acetaldehyde

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4
Q

Can taste in Budweiser due to beechwood chips

A

Acetaldehyde

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5
Q

Bitterness acceptable in

A

HEAVILY HOPPED
IPA
American Barleywine

ROASTED NOTES
American Porter
Imperial Stout

HIGH SULFATE
British Bitters
English IPA
German Pils

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6
Q

Body primarily determined by what 2 things

A

Dextrins

Medium body proteins

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7
Q

Low dextrins caused by (3)

A
  1. Low saccharification temps
  2. Excessive completely fermentable adjuncts
  3. Highly attenuation yeast strains
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8
Q

Low protein level caused by (2)

A
  1. Excessively short or long protein rest

2. Step temperature too high or low

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9
Q

High alcohol affect on body

A

Lightens apparent body

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10
Q

High carbonation affect on body

A

Decreases sensation of fullness

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11
Q

Remedy for light body

A
  1. Add dextrin malt
  2. Add UNMALTED flaked grains
    • barley
    • oats
    • wheat
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12
Q

Light body appropriate in (2)

A
  1. American Light Lagers

2. Lambics

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13
Q

Cheesy from ? compound

A

Isovaleric acid

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14
Q

Sensory threshold for isovaleric acid

A

Huge differences in ability to sense

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15
Q

Isovaleric acid causes (3)

A
  1. Old hops
  2. Hops improperly dried or stored high temps with oxygen
  3. Brettanomyces
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16
Q

Describe oxidation process for cheesy off flavor

A

Isovaleryl group removed from humulene alpha acid and becomes flavor activated

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17
Q

Isovaleric ok in (3)

A
  1. European Sour Ales
    • NOT Oud Bruin
  2. English Old Ales
  3. American Wild Ales
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18
Q

Often mistaken for diacetyl

A

Caramel

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19
Q

Yeast normally reduce diacetyl to

A

Diols

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20
Q

Causes of diacetyl (5)

A
  1. Premature removal yeast
  2. Exposing wort to O2 during fermentation
    3 Low FAN levels
  3. Yeast mutation
  4. Lactic acid bacteria
    • Pedicococcus damnosus
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21
Q

High fermentation temps promote formation or elimination of diacetyl?

A

Both

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22
Q

Diacetyl rest temp

A

60-65°F

15-18°C

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23
Q

Besides diacetyl rest what else can eliminate diacetyl

A

Krausening

24
Q

Diacetyl ok in what styles (5)

A
  1. Czech Lagers
  2. English Bitters
  3. Brown and Dark British Beer
  4. Irish Red Ale
  5. Kellerbier
25
Q

Shellfish

A

DMS

26
Q

Aroma and taste of cooked veggies

A

DMS

27
Q

DMS produced by what rxn

A

Heat induced conversion of SMM

- S-methyl-methionine

28
Q

Causes of DMS (4)

A
  1. Poor boil
  2. Cool fermentation
  3. Wild yeast or Zymomonas bacteria
  4. Pilsner malt
29
Q

DMS appropriate in

A

Pilsner based Lagers

  • American Light Lagers
  • Classic American Pilsners

Never Ales
- exception CREAM ALE

30
Q

Esters formed by what rxn

A

Alcohol + organic acid

31
Q

Esters due to (6)

A
  1. Yeast strain
  2. High fermentation temp
  3. High gravity wort
  4. Metabolism of FATTY ACIDS in trub
  5. Low pitch rate
  6. Low wort aeration
32
Q

Most prevalent ester

A

Ethyl acetate

Nail polish remover

33
Q

3 most common perceived esters

A
  1. Isoamyl-acetate ( BANANA)
  2. Ethyl butyrate (tropical fruit bubble gum)
  3. Ethyl hexanoate (RED APPLES)
34
Q

Fruity from hops comes from ?

A

Alcohols

Not esters

35
Q

Fresh cut grass or green leaves from what chemical class

A

ALDEHYDES

hexanal and heptanal

36
Q

Grassy causes (2)

A
  1. Oxidation of alcohols in finished beer

2. Improperly stored malt or hops (MOIST)

37
Q

Grassy ok in (3)

A
  1. English IPA
  2. American Pale Ale
  3. IPA
38
Q

Contributes to good head retention

A
  1. isohumulones
  2. high original gravity
  3. moderate alcohol content
  4. dextrins
  5. levels of high- and medium- molecular weight proteins.
39
Q

Styles that should have good head retention (3)

A
  1. German Pils
  2. Witbier
  3. Belgian Blond Ale.
40
Q

Styles which may have low or impaired head retention

A
  1. Eisbock
  2. Imperial Stout
  3. English and American Barleywines.
41
Q

Lightstruck is skunk and ?

A

Coffee beans

42
Q

Metallic due to

A

oxidation of lipids in

- improperly stored malt

43
Q

Onion or catty

A

Mercaptans

44
Q

Paper or cardboard

A

(E)-2-nonenal

45
Q

Dark malty beers oxidization taste

A

More sherry like

46
Q

Clove and spicy

A

Phenol

4-vinyl guaiacol

From ferulic acid

47
Q

Medicinal

A

Phenolic

From wild yeasts

  • esp chlorophenols
48
Q

Sherry like

A

oxidation of melanoidins

49
Q

bitter almonds, marzipan, dried cherries and cherry stones

A

Benzaldehyde

50
Q

Solvent like

A

Usually from ethyl acetate (ester) and fuselage alcohols

51
Q

Sweet due to

A
  1. Unfermented residual sugars
    - flocculent or low attenuating yeast
    - poor yeast health
    • low FAN
    • poor oxygenation
  2. High gravity wort
  3. High dextrin content
  4. Lactose
52
Q

High residual sweetness ok in what styles (3)

A

Strong beers

  1. Wee Heavy
  2. English Barleywine
  3. Eisbock
53
Q

High residual sweetness NOT ok in (4)

A

Dry styles

  1. American lager
  2. Berliner Weiss
  3. Gueze
  4. Saison
54
Q

Meaty brothy

A

Autolized yeast

55
Q

Yeasty flavor ok in (4)

A
  1. Unfiltered German Lagers
  2. Australian sparkling ale
  3. Gose
  4. Some Belgian ales

Davs Off Flavors (1 decks)

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