Ethyl acetate.
Description. The commonest ester in wines, ethyl acetate forms from the reaction of ethanol and acetic acid. It imparts the unmistakable and usually objectionable aroma of nail-polish remover (acetone).
Cause. Ethyl acetate frequently develops in grapes on the vine from contamination with Acetobacter spp. and other aerobic bacteria converting alcohol produced by yeasts in wounds to acetic acid. It is a frequent contaminant of thin-skinned varieties of shipping grapes and of skins of grapes pressed for juice and allowed exposure to air before being used for second runs. Acetic bacteria are ubiquitous but their activity is greatly reduced by low pH, low temperature and anaerobic conditions. Sulphite is lethal to them.
Prevention. Grapes - particularly thin-skinned varieties - should be processed as soon as possible after harvest, and for second runs, crushed skins should be sprayed with sulphite solution if they can't be submerged quickly.
Treatment. Sometimes ethyl acetate will revert to the much less evident acetic acid but usually, once detected, it is very difficult to correct. Refermentation in another must will reduce it to some extent and bubbling CO2 through a sintered air-stone, then heavy PVPP fining can be effective as a last ditch measure.
Judging. A noticeable acetone character should be considered a serious fault and the wine judged as undrinkable. At almost imperceptible levels ethyl acetate may be considered a contributor to complexity, particularly in reds. Some judges are very sensitive to it and feel justified in rejecting any wine in which the slightest traces occur.
From
An article for competition wine judges and of interest to competitors
~British Columbia Amateur Winemakers Association
