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IBU calc for whirlpool under 175F
- Thread starter pudland
- Start date
brewfun
Grandmaster Brewer
The isomerization below 180F is near zero. Other characteristics like flavor and aroma go up, but there isn't a formula for that.
Let's be clear: IBUs measure only bitterness. Not flavor, aroma or hop leaf tannins (which can lend a sense of bitterness and dryness or astringency).
Second, bitterness utilization with agitation is 15% to 20% over 30 to 60 minutes, which is about half what's expected in a boil. That utilization goes way down if there's no agitation.
Also, these isomers are typically less stable than those formed in a boil, so they leave the beer far more quickly. They tend to be "stickier" than boiled isomers and attach themselves to yeast, proteins, fermenter walls and especially foam. University of Oregon research showed huge dropoffs in IBU levels from late hops in just 20 to 30 days. Flavorwise, this isn't an issue in beers with a base (boil) bitterness of >50 IBU.
What's gained from a lower temperature steep is increased flavor and aromatics, since the lighter oils don't volatilize very well below 180F. In fact, a perfect steep wouldn't smell like much of anything at all, because if you can smell it, it's no longer in your beer.
Let's be clear: IBUs measure only bitterness. Not flavor, aroma or hop leaf tannins (which can lend a sense of bitterness and dryness or astringency).
Second, bitterness utilization with agitation is 15% to 20% over 30 to 60 minutes, which is about half what's expected in a boil. That utilization goes way down if there's no agitation.
Also, these isomers are typically less stable than those formed in a boil, so they leave the beer far more quickly. They tend to be "stickier" than boiled isomers and attach themselves to yeast, proteins, fermenter walls and especially foam. University of Oregon research showed huge dropoffs in IBU levels from late hops in just 20 to 30 days. Flavorwise, this isn't an issue in beers with a base (boil) bitterness of >50 IBU.
What's gained from a lower temperature steep is increased flavor and aromatics, since the lighter oils don't volatilize very well below 180F. In fact, a perfect steep wouldn't smell like much of anything at all, because if you can smell it, it's no longer in your beer.
Oginme
Grandmaster Brewer
brewfun said:
To be more specific, IBU are a measurement of isomerized alpha acids which, in turn, has a relationship to the sensation of bitterness.