Faults

Question 1

Acetaldehyde

Answer 1

Too agressive fermentation

• overpitching
• over-aerating

Pitching warm

Adding simple sugars before 24h

Question 2

Alcoholic

Answer 2

Hot fermentation temps > 80

High gravity wort with low pitch rate

Question 3

Astringency

Answer 3

Polyphenols (tannins)

“High HOPS, high TEMPS, high pH”

Excess dry hopping
Over sparging
Mash temp too hot

Question 4

Cidery

Answer 4

Acetaldehyde

Too many simple sugars

Question 5

Diacetyl

Answer 5

It’s a VDK

Lomg lag time

• weak yeast
• insufficient aeration

Question 6

Dimethyl sulfide

Answer 6

Corn in pales tomato in darks

Comes from S-methylmethionine

DMS not cleaned up by yeast

If due to bacteria is more rancid like cabbage

Question 7

Esters

Answer 7

Isoamyl acetate
- Banana ester

Ethyl acetate
- nail polish remover

All from stressed yeast

All come from acetyl CoA
- no longer needed after exponential growth phase

Question 8

Grassy

Answer 8

Aldehydes

Poorly stored ingredients

Question 9

Medicinal

Answer 9

Chlorophenols

Bleach and phenol reaction

Bandaids, spicy like cloves, smell like hot plastic

Phenols from YEAST react with Cl or I from sanitizer

Question 10

Meaty/brothy

Answer 10

Ham soup

Yeast autolysis

• yeast starvation
  
  • old yeast
  • long fermentation

Question 11

Metallic

Answer 11

Old malt

Too much brewing salt

Iron or manganese well water

Question 12

Oxidized

Answer 12

Oxidation of fatty acids to trans-2-nonenal

Question 13

Soapy

Answer 13

Breakdown of fatty acids in trub

Autolysis of yeast

Question 14

Solvent like

Answer 14

High fermentation temps and oxidation

Question 15

Skunky

Answer 15

Photochemical rxn of isomerized hop compounds

From blue and ultraviolet spectrum

Question 16

Sweaty/goaty

Answer 16

Always a sanitation issue

• mold
• Brettanomyces
• Pediococcus