| Stuck Fermentation |
The yeast died before fermentation completed |
Keep fermentation temp. below 90 degrees; dilute
overripe fruit with water to 25 Brix; add nitrogen (DAP) and SuperFood;
use vigorous yeast like Prise de Mousse |
| Cooked Flavors |
Fermentation temperatures too high; overripe grapes;
too many raisins |
Ferment whites at 60 deg. Or less; ferment reds
at 85 degrees or less; avoid overripe fruit |
| Burnt match odor |
Sulfur dioxide gas |
Keep free SO2 to less than 40ppm; use less SO2
in wines with low pH values |
| Sherry or Madeira odors |
Oxidized wine |
Keep all wine storage containers full and tightly
sealed; use moderate amt. Of sulfur dioxide; avoid pumps with leaky shaft
seals and avoid air leaks in pump suction lines |
| Swampy odors |
Bad corks |
Try changing cork suppliers |
| Rotten egg odors |
Hydrogen sulfide gas |
Avoid grapes with excessive sulfur residues; avoid
Montrachet yeast; add nitrogen and nutrients early; avoid hot fermentation |
| Vinegar and fingernail polish odors |
Acetic acid and ethyl acetate produced by Acetobacter
bacterium |
Keep containers full; use moderate amt. Of sulfur
dioxide but Acetobacter tolerates SO2; remove pomace promptly; keep winery
clean |
| Rancid butter odor |
Excessive amount of diacetyl |
Inoculate with ML bacteria early; control ML fermentation
w/ SO2 |
| Moldy or mildew odor |
Moldy barrels; rotten fruit; mold in hoses & equipment |
Avoid empty barrels/maintain them properly; avoid
rotten, moldy grapes; hang hoses to dry completely; keep winery clean |
| Barnyard, horsy, mousy or wet-dog odors |
Fermentation products produced by Brettanomyces
film yeast |
Keep containers full; maintain 30 ppm SO2; avoid
unknown/used barrels; get rid of dirty smelling barrels; keep winery clean |
