Lactic acid bacteria (LAB), as a group, are involved in the fermentation of malic acid and can utilize other constituents in wine. Some LAB strains are connected to spoilage, while Oenococcus oeni species is well known for conducting malolactic fermentation (MLF). The LAB population is generally low on fruit…
View PDFCork taint is a wine fault associated with contaminated cork smell also called corked wine. TCA or cork taint has been associated with the development of mold by Penicillium and Aspergillus fungi on cork trees, in sheets of cork or in corks themselves however, corks are not the only souce for contamination. Once cork taint is detected in a wine, it is too late! Aeration of a corked wine tends to release more off- odors than it removes.
View PDFBrettanomyces (Brett) is a non-saccharomyces or “wild” yeast that is the only microorganism capable of producing several milligrams of ethyl-phenols per liter of wine. The spoilage yeast can be found on grape skins and in wooden barrels. The development of these yeast are favored by the level of residual sugars, warm temperature, high pH, low sulfur dioxide…
View PDFEthyl acetate is a wine fault smelling of nail polish, glue, or solvent. Damaged fruit coming in at harvest is the first instance where microbial spoilage via yeast can produce ethyl acetate. Sound winemaking practices that reduce the incidence of oxidation and VA production also prevent ethyl acetate formation.
View PDFVolatile acidity (VA) is defined as the total of steam distillable volatile acids in a wine, which is comprised almost exclusively of acetic acid (vinegar). An increased level of VA usually indicates spoilage in wine and is regarded as a fault at or near the sensory threshold of 0.7 grams per liter. Damaged fruit coming in at harvest is the first instance where microbial spoilage and high VA can be an issue. Sound winemaking practices can go a long way in preventing high VA, including the proper use of sulfur dioxide (SO2) and minimizing oxidation.
View PDFThis summary document lists the common wine faults including the name of the fault, the type of the fault, the odor characteristics, and the chemical responsible. A wine fault is an unpleasant organoleptic characteristic including look, smell, or taste. Wine faults can come from a chemical or a microbial origin and some off-odors can be the result of multiple faults.
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