HSI

Ingredients
1

I’ve posted elsewhere that I’m working for a while in the lab at BSG (Brewers Supply Group) testing hops for alpha & beta acids, as well as HSI: the Hop Storage Index.

I am frankly surprised at the degradation of alpha acids in hops.  In the 3 months since harvest, the hops I am testing have dropped 1-2 % points in alpha from the harvest alpha.  I’m not experienced enough to know if that will continue at a steady decline or not.  I do know that the variety also influences the rate of decline.

What I am wondering is if we homebrewers are not taking this into account as much as we should - if at all.  All the hops in my freezer are 2014 hops.  They have an alpha acid % listed on the package but I’m not sure how to account for the decline, and they never list the HSI.  It seems to me this would be an important thing to factor in.  Any thoughts?  Do any of you factor in the age of the hops for calculating IBUs?

2

I don’t.  I have never thought my bitterness levels seemed low.

3

Many varieties have a storability rating. I don’t care enough to account for losses. If I do care for a particular batch, I buy as fresh as possible.

4

I dont worry about that. 99% of the time I dont even change my hop calculator to the actual AA on the package. If I were a large commercial brewer I would probably be far more attentive.

5

Same here. The vast majority of my beers are one-offs. If I were trying to recreate the same beer over and over, then this is certainly something I would be better off paying closer attention to.

6

Part of my interest in this is due to the fact that I have yet to get my IPA’s to have both the noticeable bitterness level I’m looking for.  I am casting about for what to try next.

My water salts are where they should be (300 sulfate, 54 chloride, 18 magnesium)
My pH is where it should be (5.4)
I’m using a neutral yeast (US-05)

I’ve tried hop shots.  I’ve tried 120 IBU (calculated) loads of bittering additions.

Don’t get me wrong the beers are good, and balanced, but they have an APA level of bitterness.  I’ve noticed several commercial examples that have the level of hop flavor that I like are also lacking the bitterness of an IPA - not all certainly, but a large number.

So I found myself wondering if the calculations are off because I am not factoring in the alpha losses.

My next attempt will be to use a dreaded high co-humulone hop to see if that is what I am looking for.

7

Ya, im thinking you just might have a more than average love of scorching bitterness my friend. You might have to try hop extract.

8

Your IBUs are going to max out around 100, so there’s no harm in way overshooting just to be sure that you max it out. Shoot for 200+ IBU’s of Polaris as your bittering hop and go from there.

9

Since you work at BSG, why not test some of your 2014 hops and compare the results with the labeled percentage?

10

I think that’s the answer right there, if they will let you

11

That’s a great idea.  I would if we were not so far behind.  This is the first season for the lab and we have had an amazing series of issues putting us behind.  Perhaps later when things are caught up - if I am still there.

12

How are those stored? 1-2% at room temperature wouldn’t surprise me - that’s something like a 0.3 HSI which is typical. And bear in mind it’s exponential decay.

Here’s the formula just in case you don’t have it: http://morebeer.com/brewingtechniques/library/backissues/issue2.1/garetz.html

I do the calculation every once in a while, but since I store hops in a freezer under relatively oxygen-free conditions it doesn’t usually end up being necessary. Case in point, I brewed with 2014 CTZ yesterday and probably should have bumped it up a bit, but the predicted alpha has only dropped from 12.0% to 10.2% and I’m doubting I’ll miss the ~5 IBU. It would be interesting to know how widely the HSI can vary within a given variety; if it isn’t on the packaging I just assume the typical value. If you look at something like the Hop Union data sheets they’ll at least have a range. (Of course, being at BSG you could probably just walk over to the warehouse and look at some boxes.)

13

Thank you!  I’ll check that link when I get home.

No the hops in question were stored in a refrigerated warehouse.

14

I wonder the same thing. And as home brewers we often don’t know how old the hops are when we buy them.

So I ask, why don’t hop suppliers stamp the packaging date on them?

15

+1!  I would at least expect a harvest year date on them (at least the single oz packages anyway).  Wouldn’t take much to add that.

16

Luckily, retailers stamp the harvest year on the package when you buy in bulk. As for the LHBS and suppliers that just weigh hops from bulk containers oz by oz, it’s probably not in their best interest to give too much detail. Might be this year’s crop, very well might not be.

17

And THATS the real answer!

18

I use a rough ROT to adjust hop amounts for age.  A SWAG is good enough for me, and the results bear that out.

19

I’m guessing that if HSI declines in an exponential fashion, then perhaps a large portion of the decline has already happened when the hops get to us.  Nevermind that the %AA on the package represents some statistical average from whatever lot of hops the package was taken from.  And nevermind any error in the formulas used to calculate isomerization in the boil.  In other words, there are lots of sources of error in the IBU numbers that show up on the recipe so I wouldn’t sweat it too much.

I brew with homegrown hops using my best (researched) guess of %AA and it works.

20

I’m actually pretty confident in the number that goes on the package.  Here is why:  The second stage in the pelletizing process is mixing the hop particles in very large drums in order to homogenize.  Also most of the time hops are pelletized from a single lot, not blended.  Blending is done when a large brewer requests it.  Then each run is sampled throughout the run.  The lab gets small ~3 ounce packages of these samples.  We test each sample twice.  The two need to be within 3% of each other or the result gets tossed.  Then, it is true, all of the samples for the run get averaged, but the standard deviation in AA between samples in a given run vary only by ~.02%.

That is not much of a difference.  However losing 1-2 percentage points in 3 months off of a 15.0% bittering hop (i.e. CTZ) is a significant drop.  If the rate of decline is constant, by July/August 2016 the 15.0% hop is now 7-11%!

I know that not all varieties lose AA at the same rate, and other factors come in to play but…

I did look at the MoreBeer link.  To be honest it went over my head, but I am considering making a spreadsheet with all the variables factored in, in order to make a reasonable prediction of AA losses.