Dimethyl dicarbonate

Dimethyl dicarbonate (DMDC) is a synthetic antimicrobial agent added to beverages at the point of filling, just before the container is sealed. It acts by inactivating microbial enzymes — effectively pasteurising the beverage in-bottle — and then decomposes within a few hours into carbon dioxide and very small amounts of methanol. By the time the product reaches the consumer, no DMDC residue remains. It is used in wine, fruit juices, carbonated soft drinks, and ready-to-drink teas.

JECFA's ADI is "not specified," evaluated in 1988, specifically because DMDC leaves no residue in the finished product. The methanol produced during decomposition is at levels far below those from natural fermentation products (wine already contains far more methanol from fermentation than DMDC addition could contribute). The absence of residue means consumer exposure to DMDC itself is effectively zero.

Dimethyl dicarbonate is approved in the EU, US (GRAS), Australia, and many global markets. It is a favoured alternative to heat pasteurisation for heat-sensitive beverages where flavour preservation is important. From a consumer perspective, its key advantage is the zero-residue nature: unlike most preservatives, it performs its function during production and is not present in the food at point of consumption. There are no known safety concerns associated with DMDC in properly manufactured beverages.