Kölsch Entry With Green Apple and Banana
You are head judge at a 600-entry competition using BJCP 2021 categories. An entry labeled 'Kölsch' is 5.4% ABV, 18 IBU, crystal clear, pale straw, and served at 45°F. Your panel notes a prominent green-apple acetaldehyde note, a low banana ester, a firm sulfury aroma, and a lingering grainy sweetness. The brewer's notes say German ale yeast at 18°C, three weeks at 1°C, filtered, and no diacetyl rest. A second entry labeled 'Cream Ale' is 4.8% ABV, 14 IBU, with similar grain sweetness but a clean fermentation and a light corn note. The stewards ask whether the Kölsch entry should be moved to another category, and the brewer is waiting for actionable feedback. You must judge the beer as entered and give useful process advice without rebrewing it.
1. Assess style fit and decide whether the entry should be reclassified. Explain which observations fit Kölsch and which do not.
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Judge it as entered and mark it out of style. Kölsch is about 4.4–5.2% ABV and 18–30 IBU; 5.4% is above the range, even though 18 IBU is at the low end but legal. The clear, pale-straw appearance fits. The sensory profile does not: prominent acetaldehyde is a fault, banana ester is too high for Kölsch, and lingering grainy sweetness suggests poor attenuation. A firm sulfur note can be acceptable at low levels in some Kölsch, but not alongside the other faults. Do not reclassify mid-competition; the entry was submitted as Kölsch. Cream Ale is not a better fit because the entry lacks the clean, light-fruity fermentation expected there, and acetaldehyde and banana would still be faults. Feedback should state: out of style on ABV and fermentation character; if rebrewed, target 4.8–5.0% ABV, 20–25 IBU, and a clean, low-ester fermentation.
2. Identify the likely causes of acetaldehyde, banana, sulfur, and grainy sweetness, and rank them for the brewer's attention.
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Acetaldehyde: likely incomplete fermentation or early cold crash before yeast reabsorbed it. A 18°C fermentation with no diacetyl rest and then three weeks at 1°C can leave acetaldehyde. Banana: isoamyl acetate from warm fermentation or high pitch temperature; 18°C is not extreme, but localized warm spots, underpitching, or poor yeast health can raise it. Grainy sweetness: high mash temperature, high crystal malt, or low attenuation. Sulfur: yeast strain and lagering; low sulfur is acceptable, but firm sulfur with apple and banana points to yeast stress. Ranking for attention: acetaldehyde first, ester control second, attenuation third, sulfur fourth. Action: extend a warm rest at 18–20°C until VDK and acetaldehyde are low, verify yeast vitality, control fermentation temperature, and check attenuation before lagering. For competition feedback, prioritize acetaldehyde and ester faults over sulfur.
3. Write the score-sheet feedback priorities and a realistic rebrew target for the brewer.
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Score-sheet feedback priorities: (1) lower ABV into the 4.4–5.2% range; (2) fix fermentation-add a diacetyl rest, reduce acetaldehyde, control temperature, and pitch adequate healthy yeast; (3) improve attenuation so the finish is dry and the grainy sweetness drops; (4) keep sulfur low and clean; (5) adjust hopping to 20–25 IBU with a noble-type aroma if desired. A realistic rebrew target: 4.8–5.0% ABV, 22–25 IBU, pale straw to low gold, clean fermentation with very low fruit, low sulfur, and a dry finish. Suggested score anchors for the current entry: aroma 6/12, appearance 3/3, flavor 10/20, mouthfeel 3/5, overall 5/10. The brewer should not simply filter harder; filtration removes yeast but does not remove acetaldehyde or esters once formed.