Study Guide
Exam Focus
- Hop flavor and aroma can diminish.
- Malt can shift toward honey, caramel, or toffee.
- Papery or wet-cardboard notes are common warning signs.
- Waxy or lipstick-like notes can indicate oxidation.
What to know
Oxidation can show as stale cardboard, paper, honey-like sweetness, muted hops, or dull malt.
How it applies
Warm storage, old inventory, oxygen exposure, or party-pumped kegs can speed oxidation, so servers should check dates, storage, and service method.
- Hop flavor and aroma can diminish.
- Malt can shift toward honey, caramel, or toffee.
- Papery or wet-cardboard notes are common warning signs.
- Waxy or lipstick-like notes can indicate oxidation.
Why It Matters
- Papery, stale, muted, or darkened character can signal beer that has aged poorly.
- Recognizing oxidation helps staff investigate date and storage history instead of serving a diminished product.
Practical Sensory Exercises
Oxidation practice drill
Compare a fresh beer with an older package of the same brand when available; record changes in hop aroma, malt, color, bitterness, and finish without assuming age is the only cause.
Key Terms
- Oxidation
- Flavor change caused by oxygen exposure and age.
- Staling
- Loss of fresh beer character over time.
- Cardboard note
- A papery stale flavor commonly associated with oxidation.