Low Alpha Single Hopped IPA

I made a batch of 'strong pilsner' using low alpha hops, OG of 1.111 and about 12 oz of Hall, Tett and Saaz, majority Hall to get to 71 IBUs. The Halls were only 2.5% alpha. The beer is very grassy and vegetal, even after 18 months. It is getting better, but still not what I expected. Personally I will never use that much low alpha hops again. But for you I recommend doing it. Not that I want you to brew bad beer. I'm just selfishly interested to see if you get the same results. I plan to attempt this recipe again and it will need some mods..

Cheers, and good luck

 

Is there a point of diminishing returns when it comes to hops and their boil time. If the OP was to boil for 90 mins would it extract more bitterness? Related question - does the 60 vs. 90 min boil have different effects for a low AA hop like Saaz compared to a high AA hop like Magnum or Warrior?

 

90 minutes vs 60 does result in more bitterness, but the utilization curve is already starting to get fairly flat in that range. So yes, it's diminishing returns.

 

My guess is that the AA% of the hops per se doesn't affect this difference between 60 and 90 minute utilization. But, a wort with higher AA's (whether from low or hia alpha hops) would have a curve that would flatten more quickly, after you pass 70 IBUs or so (and approach the universal speed limit of about 110 IBUs). In other words, if you have less 'headroom' for bittering, your incremental utilization will fall off more than if you were in a lower IBU situation.

 

I've been brewing a lot of beers with tons of noble hops and if I use them in the ranges you're talking about it ends up being balanced and delicious. A beer I hoped would be an IPA turned out to be a balanced amber with 12oz of noble hops and other low alpha hops. I just think to match the balance of a typical or even moderate IPA with low AA you would need as much hops as possible.

I also don't subscribe to the "grassy vegetal" theory. I've been using a lot of hops and this has never been an issue. If you're concerned, use hop bags.

 

Is the 110 based on human perception or is that a chemical/scientific property based on alpha acids?

 

There is a perception limit, but I don't know what it is. There also seems to be a physical limit related to the amount of AAs that can be isomerized and dissolved under normal brewing conditions. Then there's the phenomenon of beer having less IBUs than wort...due to yeast stripping out the AAs. One data point for which I can remember the numbers... Deschutes brewed a beer for which they calculated 243 IBUs. Actual lab measurement was 87.