by Kido Hirotaka

When hops are exposed to heat, bitterness emerges but they lose aroma. Conversely, without heat, there is no bitterness, but they impart a lovely aroma to the beer.

Brewers, thus, are able to make bitter and aromatic beers by exploiting these characteristics. Hops are added when boiling the wort, but those added at the beginning of the boil are for imparting bitterness. Hops added toward the end provide aroma. In the technique of dry-hopping, the brewer doesn’t use any of the hops added during the boil, but rather tosses them in directly toward the end of fermentation, when the beer is just about done. At this point, there is no heat and the rather fresh hops give the beer aroma.

The process of dry hopping is simple. Usually, you stuff a bag full of whole hops, kind of like a tea bag, and lower it into the beer for about a week, after which time the beer becomes infused with hop aroma. In America, however, Sierra Nevada Brewing utilizes a unique dry-hopping technique for their Torpedo Extra IPA. True to name, they stuff a torpedo-like vessel with hops, seal it in the tanks with the beer, and let the hoppy detonation begin. Usually, hops are added to the beer, but with Torpedo, it’s more like the beer circulates through the hops! They apparently tried a variety of dry-hopping techniques but found that this best imparted pure hop aroma.

We can’t forget, too, that dry hopping has been an essential part of England’s legendary cask-conditioned ale. A brewery would bring the cask to a pub after the fermentation is complete; there, the cellarman would dry hop it. Depending on the different ways the cellarmen would dry hop, you would have the same beer but with different conditioning from pub to pub. A cellerman’s choice spoke worlds.

In Japan, Baird Beer’s Suruga Bay IIPA receives a double dry hopping, while some of their seasonals have even received a triple dry hopping. How does it work? After fermentation, the brewer dry hops it, then after a week moves it to another tank and dry hops it yet again. One batch takes up a ridiculous amount of time and hops. In a recent collaboration brew, Schneider in Germany and Brooklyn Brewery in America dry hopped a weizen to the surprise of many.

While dry hopping is a simple process of giving beer aroma, for breweries, the creativity involved adds a pleasant change to long days of brewing.

This article was published in Japan Beer Times # () and is among the limited content available online. Order your copy through our online shop or download the digital version from the iTunes store to access the full contents of this issue.