Author Topic: Hop Alpha degradation  (Read 658 times)

Offline Wort-H.O.G.

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Hop Alpha degradation
« on: January 06, 2016, 02:56:59 PM »
So I ve been doing some reading about alpha degradation over time with hops. suppliers have some stats on spec sheets- % degradation at say 6 months.

Got me wondering what a reasonable expectation of a listed alpha on pack of hops- say 4.8%, how accurate or reliable would that be in determining IBU? 

I have no idea how old the hops are when i get them- 3 months, 6-months, 1-year? and is the degradation schedule related to if they are free from o2 and light exposure, and from date of harvest/packaging?

many questions- so curious if some of you have some insight.
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Offline erockrph

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Re: Hop Alpha degradation
« Reply #1 on: January 06, 2016, 03:41:24 PM »
It varies by cultivar, and also by time and temperature of storage. There is a HSI (Hop Storage Index) value for each hop variety that shows the expected loss after 6 months at room temp. Cut that rate in half for every 10 degrees C lower temperature storage. Here's a decent article if you actually want to do some calculations yourself: http://morebeer.com/brewingtechniques/library/backissues/issue2.1/garetz.html

Personally, I haven't bothered with this and just call it close enough, since I typically buy my hops in bulk close to harvest time and store in the freezer.
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Offline HoosierBrew

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Re: Hop Alpha degradation
« Reply #2 on: January 06, 2016, 03:44:38 PM »
Personally, I haven't bothered with this and just call it close enough, since I typically buy my hops in bulk close to harvest time and store in the freezer.

+1.  Same approach for me.
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Offline Wort-H.O.G.

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Re: Hop Alpha degradation
« Reply #3 on: January 06, 2016, 04:08:34 PM »
It varies by cultivar, and also by time and temperature of storage. There is a HSI (Hop Storage Index) value for each hop variety that shows the expected loss after 6 months at room temp. Cut that rate in half for every 10 degrees C lower temperature storage. Here's a decent article if you actually want to do some calculations yourself: http://morebeer.com/brewingtechniques/library/backissues/issue2.1/garetz.html

Personally, I haven't bothered with this and just call it close enough, since I typically buy my hops in bulk close to harvest time and store in the freezer.

thanks for the read. I shall not fret!
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

http://braukaiser.com/wiki/index.php?title=The_Science_of_Mashing

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Offline brewsumore

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Re: Hop Alpha degradation
« Reply #4 on: January 07, 2016, 03:10:52 AM »
I use the hop loss calculator in ProMash.  It isn't variety specific but I feel it works well.  I calculate loss from the date of purchase, unless I bought previous year hops (rare).

Offline The Beerery

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Re: Hop Alpha degradation
« Reply #5 on: January 07, 2016, 04:01:49 PM »
If they are noble, the beta will take over. Its creates a slightly harsher bitterness, but you can use them the same will little to no alpha adjustments.
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Offline dmtaylor

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Re: Hop Alpha degradation
« Reply #6 on: January 07, 2016, 08:00:40 PM »
If they are noble, the beta will take over. Its creates a slightly harsher bitterness, but you can use them the same will little to no alpha adjustments.

^^^ This.

Personally I find that as long as the hops are properly stored (cold, no oxygen), all the calculators and data available tend to way over-estimate the loss of actual real-life bitterness from the hops.  For example, some sources might say that X hop with 5% alpha will be reduced to 4% after 12 months.  But if you assume this is correct and pump 4% into your homebrewing software, it tastes too bitter as if it still had about 4.7-4.8% alpha or something like that.  It does degrade, but...... it's not so easy to pick it up, until several YEARS later.  And even then, it doesn't lose as much as you think.  That's been my experience.  I've used hops that were 3-4 years old many many many times, and based on taste in the final beer, they really never seem to lose more than 1-2% alpha acids as calculated in software.  If tested in a laboratory, then sure, maybe these beers have less IBUs.  But then, what about beta acids?  IBU tests don't look at beta at all; however, your mouth does!  Beta stays around for a long long time and probably makes up for most of it.

That's my experience.  I use lots of really old hops with great success.  Don't use them for aroma in your IPAs.  But for bittering?  That's exactly where you SHOULD be using them!!
« Last Edit: January 07, 2016, 08:02:17 PM by dmtaylor »
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Offline Wort-H.O.G.

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Re: Hop Alpha degradation
« Reply #7 on: January 07, 2016, 08:11:30 PM »
all good input-thanks fellas.
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

http://braukaiser.com/wiki/index.php?title=The_Science_of_Mashing

Serving:        In Process:
Vienna IPA          O'Fest
Dort
Mead                 
Cider                         
Ger'merican Blonde
Amber Ale
Next:
Ger Pils
O'Fest