Brewing Process and Cellar Operations
This domain tests your command of the hot side and cold side as a sequence of controlled steps, plus the cellar judgment calls that protect flavor and yield.
Core rules
- Hot side: mill, mash (conversion rest ~150–156°F), lauter and sparge, boil 60–90 minutes, whirlpool, knockout cooling.
- Boil drives off DMS, isomerizes hops, sterilizes, and coagulates protein. Vigor matters more than a rolling overflow.
- Cold side: pitch, control fermentation temperature, monitor gravity, rest for diacetyl, dry hop, cold crash, fine or filter, carbonate, condition.
- Diacetyl rest: raise a lager near terminal gravity to 65–68°F so yeast reabsorbs alpha-acetolactate-derived diacetyl before cooling.
- Dry hop 2–4 days at 60–68°F; longer or warmer contact extracts grassy, vegetal notes.
- Clean-in-place: caustic for organics, acid for beerstone, sanitizer immediately before use - never sanitize a dirty surface.
Worked example
A lager tastes of butter and butterscotch at the end of primary. Pull a forced diacetyl test: heat a sample to about 140–160°F for 15–20 minutes, cool, and smell. If diacetyl appears or intensifies, alpha-acetolactate is still present. Hold the tank at 65–68°F until the test is clean, then crash to 34°F. If the test is negative but the tank still tastes buttery, the cause is contamination or oxygen, not an unfinished rest.
Traps that cost marks
- Reading final gravity before fermentation is truly terminal, then packaging a refermenting beer.
- Dry hopping warm and long, then blaming the hops for grassy character.
- Skipping the forced diacetyl test and crashing early.
- Using a sanitizer as a cleaner - soil load consumes the sanitizer.
- Transferring with excessive splashing, adding oxygen on the cold side.