Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=220060
Story Retrieval Date: 4/25/2014 12:30:50 AM CST
How does a dash of arsenic in your beer sound?
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 micrograms 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.
The trace amounts of arsenic discovered were only slightly elevated and “it is not likely that people would get sick from drinking beers made with this filtration method,” he said. Even though the levels of arsenic were higher than—and in some cases double—the organization’s recommendation, people don’t (or shouldn’t) consume beer in the quantities that they consume water, so it’s not as much of a concern.
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.
By contrast, many microbreweries avoid using DE filtration because of its cost and the extreme precision required. “DE is risky stuff. You have to wear a respirator and it takes a lot of filtrations before you really get it down so lot of breweries choose to use pressure filtrations instead,” said Brant Dubovick, a master brewer of 10 years with a gold medal from the Great American Beer Festival for his German Maibock.
There are a number of alternatives to DE. Pressure filtrations, for example, require brewers to keep a constant blanket of carbon dioxide on top of the beer to prevent oxygen from seeping in—something that can interfere with the carbonation. The pressure from the carbon dioxide pushes the beer through filter pads, which collect unwanted residue.
While Dubovick used pressure filtration systems in the past, his new project, DryHop Brewers, a gastropub opening in Lake View late this spring, steps away from that method. “Pressure filters are quite expensive and we have a lot of space constraints,” he said. “They require more space because you have to have somewhere to put the beer when you’re done with it.”
To work around this, instead of adding the extra tank required for pressure filtration, DryHop uses biofine. Biofine is a vegetarian-friendly version of isinglass—a jelly-like substance that sits at the bottom of the tank and collects leftover sediment as the beer passes through to its final containers (kegs, bottles, etc.). Heineken also uses this type of filtration called membrane filtration.
Many microbreweries also opt not to filter their beers at all in order to maximize certain flavors.
“An unfiltered beer feels more alive,” said Josh Deth, managing partner, brewer and “chairman of the party” at Revolution Brewing in Logan Square. “Some of our beers are cloudy, but we choose for them to be like that. People filter beer to speed up the process but you lose flavor, especially hoppiness. We don’t want that.”