I'm going to brew a Kölsch soon with about 25 IBUs. I was planning on using Hallertau Hersbrucker for bittering. However, after I bought the hops I noticed they only have 2.3% alpha acid content. Using the calculator on Brewersfriend.com I calculated that I will have to use 100 grams at 60 minutes (~3.5 ounces I think) to achieve 25 IBUs.

I've never added this much hops to anything but huge stouts and IPA's so I'm worried about the hops imparting undesirable flavors.

Batch size: 25 liters OG: 1.049 IBU: 25

  • Should I use some other hop variety with higher AA content for bittering instead, or should I trust the calculator and use the Hallertau Hersbrucker hops?

1 Answer 1


Its possible that the added vegetal material will be an issue in a style as delicate as Kölsch. But like you mention, I too have loaded up beers with more than twice your proposed amount and been OK (albeit not in a Kölsch).

What would worry me more is that 2.3% Alpha Acids is really on the low end for Hallertau. I'd be worried about the quality of the hop in the first place. (I think I remember hearing that last year was a poor season in Germany for hop growers, but that's hear say I am not certain.)

If the alpha is that low then I'd expect too the other oils and character to be poor also. For future reference, I normally pass on hops like that and try and find a substitute.

If the hops smell OK to you, or you don't mind "learning the hard way". I'd say go for it. I can't hurt to use a higher alpha magnum or warrior to bitter, then use those hops to create some noble hop character later in the boil. At least that's how I've done it in the past.

  • I don't think there is anything wrong with the hops. They smell amazing, and I made sure they're real Hallertau hops, not a "Hallertau" variety grown somewhere else which is often the case with these hops. The low alpha content is unexpected though as last years Hallertau Hersbrucker was somewhere around 4.5%.
    – arnefm
    Feb 28, 2016 at 21:36
  • Great. I think that was my point. Brew with them is the answer. Its a win win as long as you consider it a learning experience either way.
    – brewchez
    Feb 28, 2016 at 23:58
  • 2
    Well, I've learned that this was a really bad idea. The beer turned out harsh, even astringent. I'm going to give it a month or two, but I can not imagine this beer will improve enough to even be drinkable. Too bad, because the beer smells great and it would clearly be good if not for the hops.
    – arnefm
    Apr 7, 2016 at 22:43
  • Bummer for sure.
    – brewchez
    Apr 8, 2016 at 10:43
  • @arnefm - I'm surprised it didn't turn out OK. I would have suggested it would have been fine.
    – Kingsley
    Jan 17, 2019 at 3:05

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