Does acetaldehyde exist in wine?

Reactions of acetaldehyde with flavonoids will affect sensory properties of wines, such as color, taste and colloidal stability especially during storage and aging. In wines, acetaldehyde is produced by yeasts, as a side product of the alcoholic fermentation, but it can also derive from the oxidation of ethanol over time. More specifically, during the first phases of fermentation acetaldehyde is produced and consumed by yeasts to be converted into ethanol to regenerate NAD+ from NADH.  Only under micro-oxygenation procedures oxygen precludes the conversion of acetaldehyde into ethanol; in these cases, high concentrations of acetaldehyde can be detected.