COMMON WINEMAKING PROBLEMS
| 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 |