Why Most Beer Brewers Today Use a Single Boil Addition

by Brad Smith on May 5, 2022 · 1 comment

This week I take a look at the reason why most beer brewers have moved to a single boil addition instead of having short duration flavor and aroma hop additions in the boil.

The History of Short Duration Boil Additions

When I started brewing back in 1987 it was very common to use short duration, (5, 10, 15 minute) hop additions which were called “Aroma additions”. The idea being that these short duration additions at the end of the boil would preserve delicate aroma oils from the hops. Even at this point it was well understood that the aroma oils in hops were volatile and did not survive a full length boil well.

We also had intermediate duration additions (30, 20 minute) that were called “flavor additions”. These were meant to be a compromise between adding some bitterness while still preserving some aroma oils in an attempt to maximize the overall flavor profile from the ops.

The Real Fragility of Aroma Oils

About 12-15 years ago the rise of the Craft Brewing revolution here in the US, as well as rising popularity of American Pale Ale and IPA styles kicked off some serious research into identifying, quantifying and characterizing aroma hop oils. Eventually studies were done to determine the volatility of hop oils in the boil.

One such study which Stan Hieronymus sent me some years back (graph shown above) examined the survivability of aroma hop oils in the boil. The graph above shows myrcene, linalool, geraniol, alpha-humulene, carophyllene, and humulene epoxide. These are the major aroma oils in hops. As you can see they are all pretty volatile and boil off quickly, which makes sense because they are aromatic compounds.

Moving to a Single Boil Addition

So if even short duration (5, 10 minute) aroma hop additions boil off a substantial portion of the aroma oils in hops, why do them? I’ll argue you shouldn’t. Instead you can move to a single boil addition to provide the base bitterness (IBU) level you are targeting, and then take hops you might have used for a short boil addition and instead move those to the whirlpool or dry hop with them.

Which is what many brewers at the home and pro level have done now. You use a single hop addition to set the base bitterness level, and then layer on whirlpool and dry hops if needed to add a burst of aroma. This is a more efficient use of the hops. If using a blend of hops, you can still add them together for a long single boil.

So how long to boil the single addition? For most beers, 60 minutes is a good boil time to target. Though you may be using a 90 minute boil overall, boiling certain hop varieties like Fuggles can result in some vegetal off flavors if you boil too long. Similarly if your boil time is too short you will get poor utilization, which is why I picked 60 minutes as a good compromise where you get good utilization without a high chance of off flavors.

Hopefully this helped to clear up your understanding of a single hop boil addition. Thanks for joining me on the BeerSmith Home Brewing Blog. Be sure to sign up for my newsletter or my podcast (also on itunes…and youtube) for more great tips on homebrewing.

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{ 1 comment… read it below or add one }

Dave King May 15, 2022 at 3:43 pm

Brad, good article, as always. I’ve been stubornly keeping 5 to 10 min. additions, but it’s time to just get rid of them. Thanks,

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