German research on trendy craft brews proves how to optimize the craft beer experience

Craft beer has a growing following in many countries, and now the hoppy beverage has inspired researchers at the Leibniz-Institute for Food Systems Biology at the Technical University of Munich (Leibniz-LSB at TUM) in Germany.

Craft beer has been around in Germany for a long time, as one of many varieties of beer than can be brewed under the German beer purity laws, which forbid the use of any ingredients other than malt, hops, yeast, and water. Craft beer is distinguished by its hoppy aroma, which derives from the addition of hops late in the brewing process. Known as "dry-hopping," this practice avoids boiling the hops with the grains in favor of adding the hops to the already fermented brew (at which point they get wet, but whatever!)

The chemical behind the craft beer's hoppy pleasure goes by the name 4-mercapto-4-methylpentan-2-one (4MMP). Any chemist knows immediately from this name that the molecule is a ketone, a class of chemicals often associated with strong aroma. The 'mercapto' in the name points to a sulfur compound, another hint that the nose will know.

Martin Steinhaus and Klaas Reglitz at Leibniz-LSB decided to measure how this aromatic compound changes during beer storage. They used a special analytical method developed to sensitively detect the 4-mercapto-4-methylpentan-2-one. They stored their beer, both filtered and unfiltered varieties, at 5 °C (41 °F) and 20 °C (68 °F) consistently for 3 months and 6 months, re-testing the quantity of hoppy odor after storage in each case.

They found a decrease to 59 and 67% in the filtered and unfiltered beers after 3 months of cold storage, while the hoppiness dropped to about a third of its original strength after 3 months of warmer storage. By the end of 6 months, the concentrations in all samples had decreased even more. Reglitz, who studied Brewing and Beverage Technology, concludes

"Anyone who prefers a beer with a strong hop aroma should not store craft beer for long."

In case you are into craft beer brewing, it will also interest you to know that Steinhaus and Reglitz tested how the amount of the 4MMP increased based on the "hopping time," or number of days the hops were left soaking in the fermented brew. They determined that after the first 2 days, little more is gained in terms of the hoppy flavor in the final product. Their chemical testing was confirmed by "sensory evaluation," ensuring that the chemistry and the reality of the experience correspond.

The partial government shut-down in the USA is bad news for craft breweries and craft brew fans, especially in light of this research showing that delays getting to market can only decrease the pleasures of the craft beer experience. While the employees of the Alcohol and Tobacco Tax and Trade Bureau (TTB) are furloughed, novel craft beer brewers cannot get new labels approved. Because the inventive and trendy craft beers change up their labels much more frequently than the major brands, they stand to be hurt more by this shut-down.

So store it cold. Drink it soon. And if you can't find your favorite brew locally or want to expand your horizons, maybe it's time for a trip to Germany to enjoy the craft beers fresh and well stored.

Read On the Behavior of the Important Hop Odorant 4-Mercapto-4-methylpentan-2-one (4MMP) during Dry Hopping and during Storage of Dry Hopped Beer in Brewing Science to learn more.