Do you, like Brett Kavanaugh, like beer? If so, treat it properly and drink it promptly. That’s the advice from researchers in Germany who studied the conditions under which craft beer maintains the edge that sets it apart from Kavanaugh’s favorite, Bud Light.
The study by the Leibniz-Institute for Food Systems Biology at the Technical University of Munich (Leibniz-LSB@TUM) found that after three months, cold stored beer loses more than one third of an important hop odorant which gives craft beers their distinctive aroma. Storage at room temperature an even faster fading.
Brewmasters achieve that strong hop aroma by an additional, late addition of hops to the young beer. In this so-called “dry hopping,” a substance with the complicated name 4-mercapto-4-methylpentan-2-one plays a special role.
Its odor is reminiscent of black currant berries. Just a few nanograms of the odorant per liter are enough to significantly influence the beer’s aroma. American hop varieties like Citra, Eureka, Simcoe and Apollo contain even more of the substance.
When beer ages
For the first time, aroma researchers Martin Steinhaus and Klaas Reglitz have precisely determined how the content of the active odor compound changes during beer storage. To do this, they examined both filtered and unfiltered dry-hopped craft beer. During the study period of six months, the researchers stored the beer consistently at 5 and 20 degrees Celsius.
At the beginning, the filtered beer contained 22 ng/kg of the odor active hop compound. The concentration in unfiltered beer was slightly lower at 15 ng/kg. After three months at 5 degrees Celsius, the content had decreased to 59 and 67 percent of the original content. For the beer stored at 20 degrees Celsius, the losses were significantly larger, decreasing to 30 and 40 percent. After a further three months storage time, the concentrations in all samples had decreased even more, in some cases to only 2 ng/kg.
“Anyone who prefers a beer with a strong hop aroma should not store craft beer for long,” concludes Reglitz, who studied Brewing and Beverage Technology in Weihenstephan.
The study appears in the journal BrewingScience.