From the HBD Archive
From: Pete Soper <>
Subject: bittering hops
Date: 1989-02-10 22:35:36 GMT

A while back I asked if any flavor or aroma was contributed by hops
boiled for 90 minutes or more. Here is a summary of what I I've learned.

Byron Burch's "Brewing Quality Beers" (p 28):
Only mentions bitter flavor from boil
Dave Line's "The Big Book of Brewing" (p 70):
90% of aroma lost with boil, no mention of flavor effects
Greg Noonan's "Brewing Lager Beer" (p 60):
[essential] oils dissipated by boiling
Fred Eckhardt's "Treatise on Lager Beers (p 10):
The hop oils, on the other hand are responsible for the
flavor, and these are often vaporized with the steam during
the boiling of the wort. Fort his reason we use the cheaper
or older hops, or even hop extract during the boiling of
the wort, and add the loose finishing hops at the very end
of the boiling process, for their flavor.
Dr. Terence Foster in "Best of Beer and Brewing" (p 34):
However, they also are quite reactive compounds, and can
be oxidized during boiling to less volatile compounds.
This suggest that even bittering hops may contribute to
beer hop character.
Len Reed in Digest #64:
Yes, the isomerized alpha acid is the *main* result of a long
boil, but the boil hops affect flavor as well. . . Your
conclusions are valid for bitter, dark beers. But I used nothing
but Saaz in my Pilsner. Experiments with Eroica (a high alpha
acid variety) were unsatisfactory.

So there appear to be subtle flavor effects and perhaps even aroma
effects from hops involved in a long boil and this is relevant
for delicate beer styles. When making highly hopped or dark styles where
a little extra dab of flavor or aroma would be buried under strong hop
or grain flavors, hop selection for a long boil is not critical.


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