MBAA Article - Dry Hopping and it's Effects in the IBU test and Beer Bitterness

[DemonsRun]

Just came across an Interesting article from Master Brewing Assoc. of the Americas (MBAA - QT-3 2016) on the effects of dry hopping, IBU, and perceived bitterness. IBU vs High Performance Liquid Chromatogpaphy (HPLC)

https://hopsteiner.com/wp-content/uploads/2016/09/TQ-53-3-0808-01.pdf

"HPCL analysis of beers that are heavily dry hopped show dry hopping removes a considerable amount of iso-alpha-acids and adds nonbitter alpha-acids and less bitter humulinones to beer."

 

[mabrungard]

Interesting. Yeast does the same thing. I guess it makes sense that adding some form of media to the beer could remove a portion of the bittering compounds, but I wouldn't have assumed that.

 

[DemonsRun]

I always attributed the dry hop compounds to aroma and some flavor but did not recognize effects of the bittering contribution of the Humulinones as it also stripped away the more bitter iso-alpha-acids. But this would explain why some of my heavily dry hopped IPAs seem more like APAs.
I also I learned that Humulinones are formed from the oxidation of alpha-acids. And are nearly identical to iso-alpha-acids w/ an additional hydroxyl group making it more soluble in beer and about 66% as bitter.

This other article is also interesting on the creation of Humulinones.

https://hopsteiner.com/wp-content/uploads/2016/07/TQ-53-1-0227-01.pdf

Humulinones appear to almost double in pellets vs. whole hops of the same variety as nearly 100% of lupulin glands are broken when pelletized, but will reach a max concentration and further exposure to air seems not to increase Humulinone concentration.