Part of the Beer Mastery school. Class 5 of 6.
The capability: you can name a beer fault and say whether it came from the brewery or from the bar.
Prerequisites: Modules 15, 29, 30, 32.
The practice
Build a fault reference. Diacetyl and oxidation at minimum — reading about them teaches nothing.
Add light-strike if you can find a clear-glass beer stored badly, and acetaldehyde.
Then taste each against a sound sample.
Then practice the sorting: brewery or bar? Diacetyl, acetaldehyde, and dimethyl sulfide are fermentation. Oxidation and hop fade are time and temperature. Light-strike is storage. Sourness across every tap is the lines.
And run the bottle-versus-tap test on anything ambiguous.
The reference
A sound sample alongside, and the packaged version for the sorting.
What you are building
The ability to route a complaint to the right place, which determines whether the fix is a phone call to a distributor or a Saturday morning with a cleaning kit.
And the recognition that some style-appropriate characters are faults elsewhere — a low level of diacetyl or dimethyl sulfide is correct in a few styles and a defect in most.
Verification and boundary
Blind: identify three faults and say the likely source of each.
Boundary: the an independent draft-quality authority manual is the technical authority.