Part of the Beer Mastery school. Class 1 of 6.
The capability: you can exonerate or implicate an entire draft system in ninety seconds.
Prerequisites: Modules 30, 32.
The practice
Take any beer available in both formats. Taste the packaged version against the tap version.
Same brewery, same style. One path goes through your system and one does not.
Do it once a week for a month across different beers.
And run it immediately on any systemic complaint — before anything else.
The reference
The packaged version. This is the cleanest reference in the entire bar curriculum because it is the same product with one variable removed.
What you are building
A reflex that eliminates five possibilities at once.
A clean bottled version and an off tap version exonerates the brewery, the distributor, the keg, the gas, and the cooler — and localizes the defect to the system, per Module 32.
Ninety seconds, and most bars have never run it.
Verification and boundary
Run it on a live complaint and record what it eliminated.
Boundary: the an independent draft-quality authority Draught Beer Quality Manual is the technical authority on draft quality.