Brief Description:
Dimethyl dicarbonate, DMDC, has a molecular formula C4H6O5 and a molar mass of 134.09 g/mol. DMDC is soluble in water and miscible in toluene (JECFA). DMDC is currently used as a preservative in food with antimicrobial action. In 1988, Velcorin was approved by the FDA for use as an antimicrobial agent in wines. The FDA approved its use in concentration levels not to exceed 200 ppm and only when yeast cell counts are below 500 cells/ mL. DMDC is classified as a “processing aid”, not a chemical preservative, by the FDA so it can be used in food processing without being listed on the ingredients. In aqueous solution it undergoes rapid hydrolysis to yield naturally present levels of methanol and CO2.
A study done shortly after DMDC’s approval found that “with a free SO2 level of 25 mg/L and the addition of 50 mg/L DMDC, control of the yeast and the bacteria was excellent at pH 3.6 or lower” (Ough et al. 1978). Cornelius Ough conducted a previous study, many years prior to attaining FDA approval, to determine DMDC’s effect on flavor and aroma profiles in wine where he concluded DMDC “imparts no off-flavor or off-aroma detectable by judges at the amounts added (200 mg/l)” (Ough et al. 1976).
Application in Wine Microbiology:
Used as an antimicrobial agent. Efficacy is inversely dependent on pH i.e. lower pH requires less DMDC for equivalent antimicrobial action (Ough et al. 1978). Often useful when a sterile wine is required and neither pasteurization, SO2, nor sterile filtration is acceptable.
References:
- Ough, C.S., L.L. Langbehn, P.A. Stafford. Influence of pH and ethanol on the effectiveness of dimethyl dicarbonate in controlling yeast growth in model wine systems. Am. J. Enol. Vitic. [online] 29:60-62 (1978)
- Ough, C.S., R.E. Kunkee, M.R. Vilas, E. Bordeu, M.-C. Huang. The interaction of sulfur dioxide, pH, and dimethyl dicarbonate on the growth of Saccharomyces cerevisiae, Montrachet and Leuconostoc oenos MCW. Am. J. Enol. Vitic. 39:279-282 [online] (1988).