Reassessment of the Influence of Malolactic Fermentation on the Concentration of Diacetyl in Wines

¹ Department of Food Science and Technology, Cornell University, Geneva, NY 14456, USA.

Diacetyl, a flavor compound having a distinct buttery character, accumulates during alcoholic and malolactic fermentation (MLF) of wine. In an effort to investigate the occurrence of this compound in US Chardonnay wines, 41 wines from 36 wineries were analyzed for their diacetyl content. Malic and lactic acid concentrations were used as an indication of the occurrence of malolactic fermentation. Concentrations of diacetyl in these wines varied from 0.005 mg/L to 1.7 mg/L. Diacetyl concentrations higher than aroma threshold were measured in 68% of the wines. Significantly higher diacetyl concentration (p < 0.02) were measured in malolactic wines. Concentrations both higher and lower than individual sensory thresholds were, however, measured in wines that had undergone and not undergone malolactic fermentation. These results suggest that, depending on the tasters diverse ability to perceive the flavorant and on the winemaking practices, diacetyl may contribute to the flavor of Chardonnay wine irrespective of the occurrence of malolactic fermentation.

Key words: diacetyl, Chardonnay wine, flavor compounds

Submitted on March 25, 1994