Elevated arsenic levels have been detected in some brands of beer sold in Germany in recent years, but the cause has remained somewhat unclear, until now.
Mehmet Coelhan, a researcher from the Technical University of Munich, reported that hundreds of German beers tested as part of routine monitoring system had higher than the World Health Organization’s suggested water arsenic limit of 10 micro grams per liter.
Coelhan presented his findings at the American Chemistry Society’s National Meeting & Exposition in New Orleans this week. He said that after testing the water, hops and malt, the team found that keiselguhr, a filtering agent used to make the finished product look clear and bright, was actually the culprit.
Coelhan stated that the World Health Organization has determined that 10 micro grams per liter of arsenic in drinking water is the “safe” limit. But some beers, in recent years, have tested higher than that.
“When arsenic level in beer is higher than in the water used during brewing, this excess arsenic must come from other sources,” Coelhan noted. “That was a mystery to us. As a consequence, we analyzed all materials, including the malt and the hops used during brewing for the presence of arsenic.”
“They concluded that the arsenic was released into the beer from a filtering material called kieselguhr, or diatomaceous earth, used to remove yeast, hops and other particles and give the beer a crystal clear appearance. Diatomaceous earth consists of fossilized remains of diatoms, a type of hard-shelled algae that lived millions of years ago. It finds wide use in filtering beer, wine and is an ingredient in other products.”
Keiselguhr, known in English as diatomaceous earth, or DE, is a powder placed at the spout of the tank that collects unwanted sediment left over from fermentation
Metropolitan Brewing, a microbrewery in Ravenswood, uses a DE filter for its German-inspired beers. “DE allows for a higher level of processing. It’s more efficient for us,” said Doug Hurst, head brewer with 25 years of experience brewing.
DE filtration is faster than other methods and is often used by larger beer companies to speed up production. Coelhan’s research looked exclusively at German beers. However, DE filtration is common stateside. American giants including Anheuser Busch and Miller Brewing Co. use DE to filter their products according to their websites.
“Coelhan pointed out that beers produced in at least six other countries had higher arsenic amounts than German beers, according to a report published four years ago. He said that breweries, wineries and other food processors that use kieselguhr should be aware that the substance can release arsenic. Substitutes for kieselguhr are available, he noted, and simple measures like washing kieselguhr with water can remove the arsenic before use.”