Effect of wine type on the detection threshold for diacetyl

Diacetyl, an important wine flavorant synthesized during alcoholic and malolactic fermentation, has been reported to have a sensory threshold of 2–3 mg/l. A comparative study of threshold for diacetyl in wines was undertaken to determine the effect of wine type on that value. Sensory threshold was determined according to the forced-choice ascending concentration series of limits method described by ASTM (E 679-79), using trained panelists. Panel detection thresholds and standard deviation from the geometric mean were found to be 0.2 mg/l and 0.32 in Chardonnay, 0.9 mg/l and 0.21 in Pinot noir, and 2.8 mg/l and 0.38 in Cabernet Sauvignon. These results demonstrate the important effect of wine type on diacetyl threshold, invalidating the use of a single threshold value for all wines.