Where do hop aroma resins come from?

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Where do hop aroma resins come from?

Postby billvelek » Sat Feb 02, 2008 1:36 pm

Where do hop aroma resins come from? Are they contained in the lupulin?

I'm starting this thread for those of you who might not happen to subscribe to the Usenet group rec.crafts.brewing ... in the hope that I can get some good advice here, too; I know that we have some very knowledgeable brewers in this forum. Thanks in advance.

**** This was my original post in r.c.b.:
I'm probably way off in left field with my thinking, but please bear with me. http://barleylegal.ca/Articles/HowToSur ... opShortage has a very interesting article about ways to cope with the hop shortage, and it prompted me to start 'thinking outside the box', so to speak, and wonder if it's somehow possible to effectively get double duty from certain hops to get the most from them in terms of BOTH aroma and bittering. The answer is going to depend upon where the resins for aroma come from; if they are in the lupulin glands, then my idea probably won't work, but if they are within the bracts (petals) of the cone, then my idea _might_ possibly work. The idea would be to use a suitable hop, such as Centennial, which can be used for either bittering or aroma, and to somehow separate the aromatic resins and oils from the lupulin glands (assuming that the resins are NOT within the lupulin), and then use each portion at the appropriate time, i.e., use the lupulin during the full boil so that the alpha acids can isomerize and bitter the beer, and use the aromatic portion only at the end of the boil or perhaps in the fermenter rather than allow them to be lost during the full boil. I'm not talking about some complicated distilling process, but rather something like a hop tea made with water because, as I understand it, the water will extract flavor and aroma from the hops; the question is whether the hop solids in the tea still contain the alpha acids, or if they will have also dissolved into the water along with any resins and oils.

For example, I'm wondering if Centennial could be steeped in water at a temperature that would not burst the lupulin glands and release the alpha acids, but only extract aromatic resins; the hop tea would then be poured off from the hop solids -- with the lupulin glands presumably remaining attached to the bracts. The hop solids would be pitched into the wort during the full boil for bittering, and later, either at the end of the boil or during fermentation, the hop tea with the aromatic resins could be added. I realize that a certain amount of the lupulin glands would invariably separate from the hops and remain in the tea, which would lower the AA content of the remaining hop solids available for the boil, but otherwise it wouldn't hurt the beer when included with the hop tea. Of course, this process wouldn't work with pellets or plugs because the processing of them no doubt crushes the lupulin glands and therefore too much alpha acid would probably dissolve into the tea.

This really sounds like it might be very plausible and not too difficult to do once some sort of a record can be established for the loss of AA% to the tea. Any thoughts? Thanks for any feedback.
**** End of first post

So far I have received just one reply, to which I have responded as follows:
**** Begin
nasacpa wrote:

> Bill, as I understand it, ALL hop resins/oils are produced by the lupulin glands.

Well, _that_ certainly puts an immediate kink in my idea. :-(

snip

> An interesting idea that I've run across is that aroma hops, used in the SECONDARY or keg,
> will contribute their aromatic components, but the bittering compounds will not leech into the cold beer.
>
> You could harvest these aroma hops, and use them for their bittering properties in your next brew.

Hmmmmm. That might work okay by using a hop bag with fine enough mesh (weave?) to strain out the
loose lupulin; I know from growing my own hops that the lupulin (or maybe the lupulin glands) will naturally
drop out of the hop cones, to some degree, because I observed the powder in my bowls after drying and again
in my plastic zip-lock bags after use. That's what I was referring to when I mentioned the inevitable reduction
of AA in my original post. But as long as the lupulin glands are not boiled I don't think most of them would be
ruptured, so perhaps most would remain in the hop bag. That just might work very well, afterall.

To accomplish the same thing with a hop tea, I have thought about straining the tea through a paper coffee filter,
which SURELY would capture all of the lupulin glands along with the hop bracts, and then I'd just dump the
whole filter into the kettle for bittering; the problem is that I don't know whether the essential oils would
pass through the filter as intended, or be absorbed by it (my _gut_ feeling is that they would probably be
absorbed, or at least a substantial amount would be).
**** End of my reply

Naturally, I'd like a second opinion on the statement that "ALL hop resins/oils are produced by the lupulin glands"; I have no basis to doubt him, but then again it is just "his understanding" which might be something he was misinformed about. Frankly, it seems more logical to me that something is going to be boiled out of the 'vegetation' that is going to have something to do with flavor just like boiling broccoli or spinach flavors water. Any thoughts and feedback will be greatly appreciated.

Cheers.

Bill Velek
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