KNOXVILLE (WATE) — The Moscow mule is an easy and refreshing cocktail for hot summer nights, but the Iowa Beverage Association is urging people who enjoy them to check their glasses.
Recently, Iowa adopted the Food and Drug Administration’s food code, which prohibits copper from coming into direct contacts with acidic foods with a pH below 6.0, like vinegar, fruit juice or wine. Traditionally, Moscow mules contain vodka, ginger beer and lime and have a pH well below 6.0.
This means that copper mugs that have a copper interior may not be used with this beverage. However, copper mugs lined on the interior with another metal, such as nickel or stainless steel, are allowed to be used and are widely available.
The Iowa Food and Beverage Commission says high concentrations of copper are poisonous and have caused foodborne illness. When copper and copper alloy surfaces contact acidic foods, copper may be leached into the food. Carbon dioxide may be released into a water supply because of an ineffective or nonexistent backflow prevention device between a carbonator and copper plumbing components.
The acid that results from mixing water and carbon dioxide leaches copper from the plumbing components and the leachate is then transferred to beverages, causing copper poisoning. Backflow prevention devices constructed of copper and copper alloys can cause, and have resulted in, the leaching of both copper and lead into carbonated beverages.