Faults Flashcards
What is Mercaptan?
Skunk aroma. From Lightstruck hops.
What is the most common chemical in the Mercaptan family found in faulted beer?
3-methyl-2-butene-1-thiol (MBT)
What fault compound produces an aroma of skunkiness?
Mercaptan.
What fault compound produces an aroma of creamed corn or tomato?
Dimethyl Sulfide (DMS)
What causes Dimethyl Sulfide in the final product?
Failure to boil for long enough or hot enough.
What fault compound produces a buttery aroma?
Diacetyl
What causes Diacetyl?
Diacetyl is a natural byproduct of fermentation. Residual yeast will usually consume the diacetyl during a post-fermentation conditioning called a diacetyl rest.
If Diacetyl aroma is accompanied by acid taste, what is the fault?
Bacterial Infection.
(Lactobacillus, Pediococcus)
What fault compound causes a Green Apple aroma?
Acetaldehyde
What causes Acetaldehyde in a final product?
Incomplete fermentation.
Occasionally incomplete conditioning.
What fault compound gives a vinegar aroma?
Acetic Acid.
What causes acetic Acid in a final product?
Bacterial Infection of Acetobacter.
What fault compound produces an aroma of wet cardboard?
Trans-2-nonenal.
