Whether or not to bag one’s hops during the boil is a dilemma every brewer experiences, with some claiming it has a negative impact on hop utilization while others swear it contributes to better beer by reducing the amount of hop matter that makes it to the fermentor. Curious of the actual impact, we put it to the test in this exBEERiment and even sent samples off to Oregon BrewLab for IBU analysis. Results are in!
Wow. I am shocked by the results. But, bagging hops (and especially cleaning the bags after) is still a PITA. I will continue throwing my hops directly in the boil.
I thought it was interesting that the original reason you bagged was because of the instructions from kits. That’s the reason I didn’t bag. The instructions didn’t tell me too. I only tried bagging a few times years later hoping it would make harvesting clean yeast easier. Really, bagging isn’t needed there either. Swirling does the trick there with or without bagging hops.
I’m a bagger but wasn’t always one. There wasn’t any real perceptible change to my end product when I switched.
I started bagging when hop seeds from whole hops were jamming the impeller in my march-pump- forcing me to disassemble the pump when I most needed it!
Now I just look at bagging as a convenient “ease of clean-up”. Easier for me anyway.
Seems an inconclusive result to me as it’s only just significant.
I’ve read that bags lower hop utilization by restricting movement. Less agitation means lower rate of isomerization. But I’ve also read that an IBU difference of 6 or under is imperceptible.
The measure IBU level is shocking. I suspect actual IBU in homebrewed beer is often way out in both directions, but I more often find that beers are insufficiently bitter than too bitter.
My understanding is that IBU estimates are for the fresh wort so its not surprising that the IBUs is the finished beer are substantially less.
Edit: My understanding appears to be non-substantiated.
Interesting. I wouldn’t have thought the difference to be this significant. FWIW, I use both pellet and whole hops in my boils. The whole ones I always bag, the pellets I do not. I think I’m getting good bang for the buck this way, with mostly effective utilization without so dang much hop leaves/trub in the fermenter.
Interesting. I’ve heard the IBU perceptibility packet is 4 IBUs. I hadn’t heard 6. I have no idea what my source was though. But now of course we have real data from Marshall who can detect differences of just 2 IBUs! Cool, I’m a convert to an even smaller 2-IBU packet based on that now.
The ROT for years is that bagged hops give you about 10% less IBU than loose hops. The analysis here seems to bear that out.
Yes, it’s almost exact! Or 7.4% to be precise, for this one data point anyway. 
My kit came with muslin bags precisely for this reason, but I have seen some without them.
Totally feel where you’re coming from, though that’s not really how stats works. Either way, since it’s just beer, I suppose it doesn’t really matter anyway 
I’ve heard this as well, curious if the oft ignored Garetz formula predicts beer IBU, as it was remarkably close to the lab measurement at 23.6 IBU.
My though exactly. Only makes me more curious if it holds for higher IBU styles.
I am really curious about this. One way of getting a feel for a style is by looking at brewery websites for their specs. Are the specs breweries quote for IBU usually for lab tested beer or can/do they post estimates based on formulas like Tinseth, Garetz, Rager?
It seems if I read 30 IBU for SABL from the Sam Adams website and then target 30 with an equation I may be way under shooting the mark. Actually, I recently made a SABL clone and targeted 35 IBU because I have always felt Beersmith/Tinseth underestimates (just based on my perception). The beer seemed to have similar bitterness but key word is seemed since I didn’t do a side by side comparison and even then it I might not be able to perceive less than a 2 (or 4 or 6) IBU difference.
I think most of them pull it right out of their arse. They calculate it somehow, but round way the hell up, via either Rager or creativity, or both.
Possibly, but bear in mind that IBU level wasn’t the only difference between the batches.
Until it’s repeated, it’s best not to overinterpret. There’s a pretty high probability of false significance at p=0.05.
The data that caught my eye was the lab report margin of error +/- 1 so if the lower reading was 1 higher and the high reading 1 lower, the two would be the same. If the margin of error means anything then you have to admit they could very well be the same.
I tried bagging for whatever reason early on, then quit, then when I got a pump I bagged whole hops, then I switched to all pellets all the time.
Awesome review. I started out without bagging and then switched to bagging for two reasons:
- I was getting a lot of hop particles in my fermenter and was worried about the “grassy taste”
- I saw a hop spider on a forum and decided to make one. I guess it was fun diy brew project.
I have considered going back to throwing and going because cleaning the bag is a PIA and I want to try some hop stand techniques. Also with having the hops in the bag your pulling them out after flameout, at least I am.
That is not my understanding. Can you point me to any reference to that? I am willing to read and learn.
My own experience was that Tinseth is the most accurate on beer samples.
Yeast selection can have a big influence. My samples used ones that were close.
I tend to be a Tinseth believer kind of guy myself. HOWEVER – and this is a really BIG “HOWEVER”…
Perhaps not the best analogy. But my point is that instead of trying to determine the exact number of IBUs for a given beer, realize that all the IBU formulae in the universe are all wrong when compared with laboratory results, and anyway, taste perception is still everything and might be totally different from either one. Aha!
Yes good point. However they’ve used the word variance (incorrectly) to mean error, so you have to wonder whether they got the math right.
I agree that one should pick a formula and stick with it. That way as a brewer you can push up or down bitterness based on some reference (your past results and the past bitterness estimates).
It’s a bit off topic for this thread, but, the main place that breaks down is when trying to clone another beer based on interpreting quoted bitterness values.