What’s the recommended contact time for hops when added at 30F? I’m looking to maximize aroma and flavor of New Zealand hops in a pilsner. The current batch I did two days of contact time and it’s underwhelming. A week? Two weeks? Will a longer contact time at lower temps prevent grassiness?
48-72 hours. Longer contact cause the hops to reabsorb oils and give you the grassiness you’re trying to avoid.
I did 48 hr, and was underwhelmed. 2oz for 5 gallons of pilsner. I’ll double that next batch to 4oz - 20z each Motueka and Rakau.
1 Like
I’ve tried the “dry hop at 35-ish degrees for 2-3 days” method, and it didn’t work any better for me than my usual method, i.e. 3-5 days at ~50F. I’ve (inadvertently) done a 2-week contact time before, and the beer was awesome. So there’s that.
In my home brewery, I have come to the conclusion that my success in dry hopping is 90% a function of using fresh, good hops. Contact time (within reason) is less of a concern to me.
Problem is, the hops that the homebrew market gets are more variable and more questionable in quality than what commercial breweries get.
2 Likes
I couldn’t agree more.
1 Like
In terms of the hop producers I know, there is no distinction. Hops are hops. There is no difference between hops destined for commercial or homebrew use.
Then why do major breweries go to hop producers to select a particular batch of hops? If there’s no difference that travel is a waste of what I understand is a very tight margin in the brewing industry.
1 Like
I’m curious about the concept of hops reabsorbing oils during long dry hop sessions…I’ve seen this mentioned in a few discussions, but I can’t say I’ve seen cited evidence for this beyond reference to a presentation or gray literature. I did a quick skim through two commonly cited pieces of technical literature (Lafontaine & Shellhammer, 2018, 2019), neither says anything about hops reabsorbing the oils (unless I missed it!), although the former is more concerned with hop load than time. There is an oblique mention in a web page from Rahr to iso-alpha acids being absorbed, which I’m assuming bitterness rather than flavor. Polyphenols seem to increase, so I wonder if it’s not stuff getting absorbed, but polyphenols swamping out the “nicer” flavors.
This isn’t to say it doesn’t happen - I’m just looking for a bit more on the mechanism, or if it’s a brewing idea that hasn’t been fully explored. I’m suspecting it’s somewhere in the technical literature, if anywhere. Anyone know?
On the one hand, this would seem to be a minor technical quibble, but it could be of practical import in meaning that some hop products or types of hops could stand up to longer dry hopping sessions versus others. (as seems to be the case with products like Cryo Hops)
Lafontaine, S.R. and Shellhammer, T.H., 2018. Impact of static dry‐hopping rate on the sensory and analytical profiles of beer. Journal of the Institute of Brewing, 124:434-442.
Lafontaine, S.R. and Shellhammer, T.H., 2019. Investigating the factors impacting aroma, flavor, and stability in dry-hopped beers. MBAA Technical Quarterly 56:13-23.
1 Like
I think there are several misconceptions here. The commercial brewers don’t buy all the hops. Usually there are lots of the same left after their selection. There are also homebrew distributors there also, doing selection.
2 Likes
I too am curious about the mechanism. The notion that hop oils diffuse into the beer down their concentration gradient, only to reverse direction after a day or two and be reabsorbed, doesn’t really make sense. If this is real, what is the mechanism that (seemingly) moves the oil molecules against their concentration gradient and back into the hop particulates? Enquiring minds want to know!
It’s certainly true that commercial breweries don’t buy all the hops, but it’s also true that they buy the best hops. Much of what is left over is still excellent quality, but some is not. With a given hop, I never know what I am going to get when I open a bag. Example: Last week I opened a bag of lupo citra, and it was awful, nothing but onion/garlic. This has happened many times over the years. It has also happened that I open a bag and there is practically no aroma to the hop, or it smells like dirty sock. (To be fair, this could be due to how the hop vendor re-packages the hops.)
All this to say that dry hopping is somewhat of a crap shoot. For this reason, I keep a wide variety of hops on hand. If one doesn’t pass the smell test as I am about to dry hop, I can make a last-minute sub.
2 Likes
I could be out in left field here: I thought I understood that after 3-4 days contact time, rather than the favorable components reabsorbing, the majority of favorable components have been released and more and more unfavorable components (chlorophyll?) begin to take over overshadowing the more delicate favorable components leading to a hay/grassy taste. 
At any rate, I use 3-4 days because I thought that’s what is happening.
I’ve yet to try it, but I have some Spectrum goo that is supposed to be a more efficient way to ‘dry hop’ and eliminates a lot of issues. We’ll see.
2 Likes
Yeah, that is what I think is probably happening (unless there is evidence otherwise).
I just picked up some Spectrum at the LHBS today…interested to try it out (probably in conjunction with some Cryo or similar) and see if it’s worth the hype.
1 Like
From the RahrBSG article above
Several studies have shown that concentrations of monoterpene alcohols and hydrocarbon hop fractions reach near-full extraction in beer after being on dry hops for just 24 hrs. Further, some of these constituents can come out of the beer solution and back into hops due to those aroma compounds’ hydrophobic nature.
1 Like
Ah, I had missed that in my initial skim. Thank you!
I’m still having a dickens of a time finding the actual primary literature that supports this, though. I’ve done a quick pass through Wolfe’s (freely available) master’s thesis, and there is mention of polyphenols absorbing some hop compounds, and yeast doing so, but nothing about various aroma/flavor compounds going back into the hops themselves. Maybe it’s in the Wolfe et al. 2012 paper, but I can’t access that (and am not inclined to pay $40 for a short PDF).
I found a clue in Scott Janish’s article from his modern IPA book, which also references the Wolfe thesis specifically - “Even more surprising, due to the hydrophobicity of some hop aroma compounds, extended dry hopping can cause removal out of the beer and back into the spent hops.” – but again I’m hard pressed to find the specific part of the thesis that says this (beyond the above mention of polyphenols and yeast and plastic liners). Anyone else have better luck? It’s quite possible I’ve missed this. It doesn’t look like they measured the characteristics of the remaining dry hop residue, so I’m not sure re-absorption was even testable here.
Sorry if I’m being a bit persistent on this - in my life as a scientist, I have been mis-cited enough times in the literature to know that I don’t trust citations unless I can view them with my own eyes! (and I also worked my Ph.D. on a topic that was a “true fact” piece based on 40+ years of common knowledge that turned out to be shakily supported at best, so I’m always turning a skeptical eye to these kinds of things!).
4 Likes
I agree: it doesn’t make intuitive sense. One generally thinks of solutes migrating across a concentration gradient until an equilibrium is achieved. If the compounds are hydrophobic, you’d expect them not to extract into the beer in the first place.
But reality isn’t always immediately intuitive.
3 Likes
I would agree that dissolution of oils into the beer will eventually reach equilibrium, not a reversal. Colder temps will slow dissolution and and the time required to reach equilibrium. I think my issue was the hops never really mixed well with the beer as they sat at the top of my carboy for the full 2-days. In retrospect, I wish I had gently agitated the carboy to encourage better mixing. That and a couple extra days.
i know a lot of you use a hopbag. if you dryhop at 30F, does it kind of automatically coldcrash?
Thoughts on this aspect?
No bag for me. I cold crash first, then once it reaches temp I dry hop.
1 Like
It’s not only duration of dropping.
1 Like
This is great, thank you!