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Last month I made an IPA with some experimental grapefruit hops with 18% AA but the final product turned out with very low bitterness and low hopppy flavor.

The first thing in my head was that it could be because of the weak boil I had the day I brew it due to technical difficulties (208 F was my average boil temp.). The other thing a suspect could have messed with my bitterness is a larger than required pre-boil wort volume.

My hop schedule was: 1 oz @60 min 0.5 oz @30 min 0.5 oz @10 min 0.5 oz @5 min 0.5 oz @flame out 0.65 oz Dry Hop

Jorge Gautier
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1 Answers1

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A difference of a few degrees (208 vs 212) is not very significant from an isomerization perspective. Studies have shown that isomerization continues to occur in whirlpools at or below 200 degrees.

Things that could have affected utilization:

  • Wort strength - higher gravities will lower utilization
  • You mentioned extra pre-boil volume - as long as you hit post-boil numbers from your recipe that shouldn't affect anything, but having extra post-boil volume would cause lower bitterness and gravity than the recipe indicates
  • The hops could have been mislabeled - were they from a reputable supplier?

What are you comparing the beer to to determine that bitterness and hop flavor are low? Those hop amounts are lower than I would normally use in an IPA where I was shooting for excessive hop character.

Chris Marasti-Georg
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  • Thanks for the info. I was trying to compared it to any average IPA.. Maybe Stone's IPA.. but from what I can taste this is less hoppy than typical a pale ale.. I used a total of 3.6 oz of these hops, I guessed that from their high Alpha Acid percent this will be enough to make a pretty hoppy beer – Jorge Gautier Jun 26 '14 at 18:23
  • Why do you think the extra volume (if boiled off) would cause less bitterness? I would have said it would cause more - hop bitterness is mostly a function of the amount of solids that the alpha acids can bind to before dissolving in the wort. A more diluted wort has fewer solids per unit area, which makes hop utilization slightly better. – mdma Jun 26 '14 at 20:51
  • I just thought that the hops will dilute more causing the hops to back down... – Jorge Gautier Jun 26 '14 at 21:04
  • I see now you said extra post-boil, so that makes sense. +1 – mdma Jun 27 '14 at 13:58
  • "Studies have shown that isomerization continues to occur in whirlpools at or below 200 degrees" - What studies? Do you have any links? I was under the impression that isomerization quickly drops off under 212. – Chris Dargis Jun 27 '14 at 14:08
  • @ChrisDargis Did some digging, and the best I could find was based on altitude. Since we know that water boils at 208 degrees at an altitude of 2000 feet, we can use the equation here to see that utilization would have dropped by about 7-8%. http://hbd.org/hbd/archive/4125.html – Chris Marasti-Georg Jun 27 '14 at 19:38
  • @ChrisDargis re: whirlpool, this article has some anecdotal numbers from pro brewers: http://byo.com/component/k2/item/2808-hop-stands – Chris Marasti-Georg Jun 27 '14 at 19:39
  • My boils never go above 200F (6500' elevation), but they are strong boils. I often think I don't get what I wanted out of hops, so wonder if it is limited by the elevation. – Wyrmwood Jul 01 '14 at 21:51
  • heh, guess I should be altering them... http://hbd.org/hbd/archive/4125.html – Wyrmwood Jul 01 '14 at 21:54