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Alpha acids degradation over time

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  • Alpha acids degradation over time

    Hello everybody! My name is Damiano, a professional brewer from Verona, Italy.

    Feel free to delete this post and/or redirect me to another concerning the same topic.
    I've been searching the internet for a while about the effects of age on hops alpha acids.
    How do you get consistent IBU results? Do you use online calculators or a more practical rule of thumb?

    Thanks in advance!​

  • #2
    Greetings Damiano! Have you studied and used HSI for adjusting bitterness? Personally, I try to use fresh hops and make small adjustments to those that are older. HSI may be used to fractionally raise hop use for consistent bittering as hops age and alpha acids decrease. Of course that's doing it based on numbers alone--and even those are best guesses. Better if you add more subjective results. If you are not measuring bitterness directly, then formalize a tasting panel to judge bitterness as part of a periodic review of your beers. If you keep good records, you can see trends develop and learn how your particular hops manifest bitterness in your particular beers. Don't forget that proper storage minimizes alpha degradation. Best of luck!
    Phillip Kelm--Palau Brewing Company Manager--

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    • Damiano_casella94
      Damiano_casella94 commented
      Editing a comment
      I will definitely take that into consideration, as well as good storage as I already do. Thanks for sharing, Philip!

  • #3
    I recommend reaching out to Oregon State University, Indie Hops, and Yakima Chief. I've had discussions with their representatives in the past regarding "Vintage Hops".
    Cheers!
    Banjo Bandolas
    Probrewer.com
    v- 541-284-5500
    banjo@probrewer.com

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  • #4
    If the hops are a few years old and particularly if they have been stored warm, also consider the effect on flavour. I had to use up a few tonnes (!!) of old stale hops following a takeover of another brewery and there was a hugely noticeable difference in flavour, even when used as bittering hops only from what they should have been like. As for their use as aroma hops - forget it.
    dick

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    • Damiano_casella94
      Damiano_casella94 commented
      Editing a comment
      Luckily I don't have to deal with such a huge amount of hops and I can buy fresh ones, and my concern is mainly to get my numbers right, but yeah, I remember having to use 4 years old enigma hops and it wasn't pleasant. Thanks for your comment!

  • #5
    Originally posted by Damiano_casella94 View Post
    Hello everybody! My name is Damiano, a professional brewer from Verona, Italy.

    Feel free to delete this post and/or redirect me to another concerning the same topic.
    I've been searching the internet for a while about the effects of age on hops alpha acids.
    How do you get consistent IBU results? Do you use online calculators or a more practical rule of thumb?

    Thanks in advance!​
    Hi Damiano!

    Usually we use the hop storage index (HSI) to get a rough idea of how much alpha acid content has been lost during storage and adjust recipes accordingly.

    The HSI is a relatively old metric, and Oregon State University has done some more recent work on the subject - I would encourage you to look for publications from the Shellhammer laboratory.

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