Anybody read this thesis? Any thoughts? I noticed the author is scheduled to present this data at the World Brewing Congress Portland 2013. Ran across the info while I was perusing Indie Hops’ blog.
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/34093/Wolfe_thesis.pdf?sequence=1
Interesting. I think I’ll go out and agitate the Belgian Imperial IPA I’m dry hopping in the garage. That might be the closest homebrewers can come to stirring.
Steve
Thanks for posting that link. Need another pot of coffee to read through the rest, but good stuff.
Edit. Looks like those that say you get differences in pellets and whole cones are right. This may also show why the Sierra Nevada torpedo has proved usefull for them.
Thanks for the link. Very interesting indeed.
wow - thanks for posting. am going to read it, but its gonna take a while…
Insight in how to get rid of that unpleasant onion/foot aroma with certain hops!
[quote][…]it had been shown that adding granular copper dramatically reduced the presence of currant-like and onion aromas in beer[…]
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Hmmm… looks like a Summit/BB IPA may be in the works…
WOT? No comments on the possibility that you may be able to shave “days” off your dry hopping regimen?
The author makes the conclusion that dry hopping (unstirred) for more than 6 hours (with pellets, it was longer for cones) is accomplishing little in the way of additional aroma, and that extended periods of dry hopping are actually counter productive. Torpedo, Randall, Rocket…all used to provide increased aroma.
Could this partly be because of the shorter contact time with the hops?
Also, dry hopped hops still have all their bittering compounds in tact…Could we throw 'em in the freezer and use to bitter the next batch??? I always enjoy saving a few bucks.
I’m planning some experimentation soon.
Kinda looks like I’m doing the right thing…I don’t weight the hop bags but I do swirl the fermenter a couple times a day.
I had seen references to the aromatics being extracted in 24 hours. Much new stuff here to read and understand.
I have for sure noticed that if I drop a bag of hops in the keg and shake to carb it immediatly has some hop aroma. and I don’t notice a significant increase the next day so that actually makes sense to me. by rocking the keg with the hops in there I am extracting most of what will be extracted in just a few minutes/hours. nice.
It’s the time Denny, not the stirring that’s the real eye opener here. The stirring is being proposed as an even better/faster way of extraction in a commercial setting…we don’t have or even want the ability to continually agitate in a homebrew situ. Look at the graphs on page 40 & 41. After a day, you’re actually decreasing your aroma compounds. It’s really some pretty unexpected results.
Yes. I just changed my current plan. As I mentioned above, I’ve got a Belgian Imperial IPA being dry hopped right now, due to be kegged on Friday. I am going to add a couple of ounces of Citra that morning before I transfer.
Steve
I have a Bitter on tap that tastes very British. One thing I decided to do was only dry hop for 3 days, as that is about the time the hops would have in the cask before it is empty. Pulled the hops out after 3 days, and it tasted very familiar.
Also had British malts, hops, WLP-002 and the pale ale water profile with lots of sulfates. 
It will probably be a while before I can digest all of this, but it sounds like dry-hopping overnight in my bottling bucket, then bottling the next day, may be worth a try sometime soon. Heck, it may be worth a try as a second wave of dry-hopping even if I’ve done one “traditional” round of dry-hopping in the fermenter.
Oh sweet! Thanks for posting this. Gonna read it Thursday or Friday.
I only just glanced through this and it’s some really good information. Would be nice if we started gathering a library of homebrew literature that’s based on solid science and experimentation and make it available for everyone.
Wow. There is alot of info there! I wish it was in a book!
Section 1.3.4 provides support for the theory that first wort hopping provides a mellow bitterness because of the precipitation of polyphenols with protein during the boil. This section doesn’t address how aroma and flavor survives the boil.
The aroma can come through if certain compounds that are soluble (linalool and geranol) combine with the sugars for form glycosides. The yeast is thought to break the bonds to get the sugars. The compounds left are the refined aromas the German brewers like. The essential oils like myrcene are only had through dry hopping, which the Germans do not typicaly do.*
Read the post from 2/16/2012 titled linalool.
Neither article indicates that glycosides are formed in the wort although that is not surprising as the first article is about dry hopping and the author of the second article indicates that most of the research is in German. Both articles indicate that the glycoside can be cleaved by acid.