Fermentation Off-Flavor & Defect Troubleshooter
Diagnose rotten egg sulfur smells, DMS, stalled fermentations, haze, and harsh fusel alcohols with certified BJCP/WSET resolution steps.
All Defects
Sulfur & Aromas
Oxidation & Contamination
Fermentation Health
Off-Flavors
Clarity & Appearance
Clarity & Appearance
Persistent Cloudiness / Haze That Won't Clear
Root Cause
Pectin haze from real fruits, suspended yeast cells, or heat-coagulated protein haze.
Step-by-Step Resolution
1. Add 1/2 tsp Pectic Enzyme per gallon (double dose if alcohol is already present).
2. Cold crash at 34°F - 38°F for 5-7 days.
3. Fine with Sparkolloid or Super-Kleer KC.
Prevention Tip: Add Pectic Enzyme 12-24 hours prior to pitching yeast when using real fruits.
Fermentation Health
Stalled Fermentation (Gravity stopped before target FG)
Root Cause
Temperature drop below yeast range, pH drop below 3.2, alcohol toxicity limit reached, or yeast exhaustion.
Step-by-Step Resolution
1. Test pH: if below 3.2, add Potassium Bicarbonate to raise to 3.4 - 3.6.
2. Warm fermenter to 68°F - 72°F.
3. Gently swirl lees without oxygenating.
4. If dead, pitch a starter of EC-1118 or K1-V1116 rehydrated with Go-Ferm.
Prevention Tip: Monitor pH during active primary and keep fermenter in recommended temperature zone.
Fermentation Health
Yeast-Bite / Rubber / Meaty Taste (Yeast Autolysis)
Root Cause
Leaving finished brew sitting on gross primary yeast lees for 3+ months in warm ambient temperatures.
Step-by-Step Resolution
1. Fine with bentonite or activated carbon to absorb meaty autolytic compounds.
2. Blend with fresh young batch to dilute off-flavors.
Prevention Tip: Rack off primary gross lees within 3-4 weeks after active fermentation ceases.
Off-Flavors
Geranium Leaf Smell (Geraniol Off-Flavor)
Root Cause
Malolactic bacteria (MLF) metabolizing Potassium Sorbate added to sweeten or stabilize.
Step-by-Step Resolution
1. Geranium off-flavor cannot be removed once formed.
Prevention Tip: NEVER add Potassium Sorbate if Malolactic Fermentation (MLF) is active or incomplete; ensure SO2 inhibits MLF first.