Experiment - Ethanol humulone extraction

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OhSoHumuLonely

OhSoHumuLonely

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So I have done a search and a lot of the people I've seen posting about hop extracts seem to be trying to extract hop flavors and aromas from their hops to add to their beer.

While I personally wouldn't want to dump a bunch of grain alcohol into my fermented beer, I completely understand that, but the experiment I have been considering all day is this:

Alpha acids do not dissolve well in water. They are slightly soluble, and as they dissolve in boiling water, they convert to iso-alpha-acids. The conversion allows more alpha acids to dissolve in the water, which is why more time is needed to allow more to covert and more to dissolve. When I looked up the solubility of one alpha acid (humulone), however, it appears it is quite soluble in ethanol, and this is actually the main way they extract alpha acids from hops to make purified humulone (after further purification).

It seems alpha acid utilization starts to level out around 25%. I want to beat that. I am an organic chemist, and a 25% yeild is something that would get scoffed at in modern chemistry.

Therefore, here is my experiment:

1) Soak 0.25 oz medium alpha acid hops in a small amount grain alcohol for an extended period of time (like 1 week or something, or more, the longer, the better, I'd guess). Alpha acids are large molecules, so they will not dissipate like flavor and aroma molecules would. If I do several small extractions, like split batch sparging in an MLT, I'd say that'd be even better.

2) Shoots for 2 gallons of wort post-boil. Split into two 1 gallon batches.

3) Add ethanol hop extract to one gallon and bring to a boil. Let boil until it reaches 212, when I would assume all the ethanol to be gone. Boil for 2 hours

4) Bring gallon #2 to a boil and add 0.25 oz of same hops (from same bag) to the boil. Boil for 2 hours.

5) Add no flavor or aroma hops.

6) Ferment side by side, do everything the same, bottle, taste, see if extraction version comes out more bitter.

Theoretically, the ethanol should extract well over 25% of the alpha acids. Once the ethanol is gone from the boil, as long as I've stirred well enough to keep the alpha acids from scorching on the bottom of the pan, they should slowly convert into iso-alpha-acids, and I would expect to have a more bitter beer with the same amount of hops (therefore allowing for more efficient bittering later on, and more economical, if the hops are more expensive than the grain alcohol I end up using... either way, I'm a chemist, it's worth it for the learning to me).

What do ya'll think?
 
I have had similar thoughts, but my train of thinking is to utilize alcohol extraction for the aroma flavor additions...I have no problem achieving bitter.

Not sure if this is possible...

I think the commercial hop extracts are done w/ CO2??? and perhaps vacuum...IDK, out of my area of expertise...
 
I am going to revise my experiment some. I posted too early. I have decided to try to do something with bittering, aroma, flavor, and maybe even doing an extraction of double the amount and adding it continuously over the end of the boil. The issue I see with that is that the alpha acids will be dissolved either way, and the addition of the ethanol will likely add a lot more bitterness than flavor and aroma hops normally do. Maybe this is a way to shorten boils, though, if it works that way. I shall see.
 
I use grain alcohol to extract hop oils from pellets for aroma in my low ABV "IPA" In a low ABV beer, there is not enough ethanol to extract the oils very well. I use a minimum of everclear and basically make a thick paste and let it set for just 1 hour and then I use this to "dry" hop with. Works great and adds only 0.3% ABV to the final product.

Now with alpha acids, you also have a solubility issue, but also an isomerization step as well.

What exactly is meant by 25% utilization? Where is the loss occurring? - this is the important question! If it were simply extraction of the alpha acids from the hop material, than one would think that using a more finely ground material would result in significantly better utilization, but it is less the 5% (whole vs pellets). This suggest there are losses that are occurring after the alpha acids are removed from the plant material. Further, boiling a lot longer does not result in significantly better utilization as one would predict if the isomerization rate alone were the key. Wort is a pretty complex mixture with all kinds of things to bind all forms of the alpha acids and reduce utilization. Somehow it is being lost post extraction. If this were not the case, if one only utilizes 25% per usage, then in theory one could re-use the hops again to extract more. This does not work.

I've messed with this a little bit with some success. Ethanol is a good solvent for alpha acids, but so is cooking oil. And 212F is good for isomerization, but 350F is really good! Sauteing hop pellets in cooking oil is a great way to extract and isomerize the alpha acids! The whole lot went into the boil kettle! I simply added some lecithin (equal volume) to emulsify the oil and had no problems with head retention.
 
There is a nice write up here

Hops and hop products

Isomerised hop pellets
The pellets for isomerised hop production are produced in a similar way to standard pellets (see Figure 3) with about 2% magnesium oxide added during the pelletising process. These “stabilised” pellets, packed in an inert atmosphere are heated to 50°C for approximately 14 days, when up to 99% of the alpha acids are isomerised in situ, giving wort utilisation rates of 80 to 90%, and final beer utilisation rates of up to 70% The handling and processing of isomerised pellets is similar to regular pellets. See Table 3.
Click to expand...

So it appears that isomerization is pretty important, but there are still significant kettle losses.
 
Chemist here as well. Let me add my 2 cents because I have thought long and hard about maxing IBUs. Even adding extracts doesn't get you max IBU in the end. Also, hops are extracted with supercritical CO2 to keep freshness, not ethanol.

You have four major forces working against you that prevents maxing IBUs in beer. Keep in mind, IBU translates directly to iso-alpha acid concentration.

1 - Hop oils are volatile. My best guess to poor conversion (even with oil extracts) is that your oils are simultaneously isomerizing and being driven off during the boil. Oils float on top of water so they can easily be driven off in a boil before they isomerize.

2 - Thermal degradation. You boil and let the beer sit at room temp for at least 2 weeks so the iso-alphas are constantly degrading from the second they are created.

3 - Oxidation. It is hard to homebrew in inert atmosphere so you are losing iso-alphas to oxidation as well.

4 - Surface binding. Hop oils are well known to bind to surfaces so any precipitate will take some out and even your pots and carboys will bind too.

How do you get around this? Add isomerized alphas to your beer right before kegging / bottling so you can chill it and minimize degradation. This product already exists but you can DIY in a sneaky non-extract fashion.

Here is a trick that I have tried but I haven't been all scientifical about it yet so maybe you may be interested. I have done this three times but always to an IPA that is already bitter so I have never "validated" with a 0 IBU batch to see how well it works.

If you want to directly measure IBU, find the HPLC assay from ASBC because the UV based one isn't specific and goes to hell with dry hopping.

Put pellets in a tight sealing tube and purge with inert gas. Oven bake at 100C for an hour to isomerize. Dry hop with them and you will be giving your beer a late IBU boost that should max the soluble iso alphas. If the alphas isomerize, they will dissolve in the beer and no extractions are needed.

The best way to see if this works is to brew a beer with only late addition hops to minimize the IBUs. If the beer is bitter as F after dry hopping with isomerized pellets, then it works.

What I really want to try for a good control is a beer with no hops then add only baked hops as a dry hop perhaps in two separate additions a week apart. I just don't have time though!
 
Wait... when you say ", MI" what part of MI do you mean? When I say that I mean....... I am a Michigan fan, not a PSU fan despite that grad school choice....


Despite all that... I can do this... Maybe not the HPLC... but maybe I can drive to undergrad and do all that. The HPLC's are pretty heavily used here at grad school.

I will do the test you suggest, but I will include a "normally bitter hopped" beer, though. Just for a normalization.
 
Not sure if it helps, but I also tried making an ethanol hop extract using whole leaf hops, and found that longer is not better if you want good flavor. The resulting flavors I had were very vegetal. I've never repeated the experiment, so I don't know if that flavor was due to my pressing the hops to remove the extract or my leaving it in the everclear for 3-4 days (rather than, say, 30 minutes to two hours). At any rate, I prefer traditional hop usage, at least for flavor/aroma.

Oh, and I almost forgot to add that the ethanol seemed to have isomerized the alpha acids, because my hop extract was extremely bitter. No boil necessary.
 
nobeerinheaven said:
This is probably not from isomerized alpha acids, but more likely from polyphenols in the hops. These taste bitter and can contribute to the perceived bitterness of a beer (beyond what the IBUs suggest - they don't count towards IBU #'s) The polyphenol levels vary from hop to hop, some add can add quite an extra "bitterness" when you dry hop with them.
Click to expand...
 
nobeerinheaven said:
Oh, and I almost forgot to add that the ethanol seemed to have isomerized the alpha acids, because my hop extract was extremely bitter. No boil necessary.
Click to expand...

pjj2ba said:
This is probably not from isomerized alpha acids, but more likely from polyphenols in the hops. These taste bitter and can contribute to the perceived bitterness of a beer (beyond what the IBUs suggest - they don't count towards IBU #'s) The polyphenol levels vary from hop to hop, some add can add quite an extra "bitterness" when you dry hop with them.
Click to expand...

I would think that since humulone is soluble in ethanol, you'd have very high concentrations of preisonerized humulone and other alpha acids. They, too, are very bitter like iso-alpha acids.
 
I've heard ethanol is capable of isomerizing some alpha acids (from a biochemist phd I know). But I have no way of testing whether or not they were isomerized.
 
Could you use NO2 as an extraction method? I know you can make Green Dragon this way, and it has been used quite long time in perfume industry and in molecular gastro/mixology. I have used it to infuse spice and herb flavours to different liqueors for some time now.
 
NO2? Nitrogen dioxide? I have no access to it, but it doesn't seem like it would be used for food grade extractions, I wouldn't think.
 
The commercial producers of extracts use liquid CO2, if it hasn't been mentioned yet.
 
I think raestlyn means N20. More and more upscale bars are using whipped cream dispensers to make fast herb infusions (pressurized extractions) for mixed drinks. It is on my to do list with hops for a fast "dry" hop
 
I gotcha. I gotcha. Sorry about that. By the way, I have not had time to try this experiment yet, with the semester starting and going nuts and all. I will get around to it before long, though. I will definitely shorten my extraction time, however.
 
pjj2ba said:
I've messed with this a little bit with some success. Ethanol is a good solvent for alpha acids, but so is cooking oil. And 212F is good for isomerization, but 350F is really good! Sauteing hop pellets in cooking oil is a great way to extract and isomerize the alpha acids! The whole lot went into the boil kettle! I simply added some lecithin (equal volume) to emulsify the oil and had no problems with head retention.
Click to expand...

Wow, that's an awesome idea. How long did you cook them? Did you still do a full 60 minute boil?
 
LovesIPA said:
Wow, that's an awesome idea. How long did you cook them? Did you still do a full 60 minute boil?
Click to expand...

I cooked them until they looked done :cross: Actually only half joking. I think it was around 10 min. tops. The oil was VERY bitter!

I just did a 20 min. boil - that was my reason to do this - reduce the boil time. This was for an all grain pale ale. Turned out OK. I suspect a longer boil might have helped some of the other flavors though


Hmmm. I have a Coopers kit someone gave me. Maybe I'll just do a quick extract batch (no specialty grains) and saute up some hops and add that to the mix (with the lecithin). I'll even do it as per the kit instructions which is NO BOIL. Maybe I'll dry hop it with some vodka soaked hops too. I'll skip the provided yeast and use something else though.
 
Why not stuff a soxhlet extractor with magnum, then poor a bottle of vodca into the boiling flask?

It might not be the most efficient method, but it might be an OK test for a few of the ideas expressed in this thread.
 
Sweet man, I've only gotten the chance to use one of those once. I've been looking for an excuse. Awesome! I'd say, in my mind, coolest idea yet!

Sent from my PantechP8010 using Home Brew mobile app
 
OhSoHumuLonely said:
Sweet man, I've only gotten the chance to use one of those once. I've been looking for an excuse. Awesome! I'd say, in my mind, coolest idea yet!

Sent from my PantechP8010 using Home Brew mobile app
Click to expand...

Worst case outcome, you can do a simple distillation out of the same boiling flask and get high strength "hop liqueur". The volatile oils are alcohol soluble too. Blend the product of that with a little water and it may *lush* like absinth, if it's not already cloudy.

So... on second thought, maybe not magnum. Maybe something like centennial.

Give it a shot.
 
Nobody’s mentioned pH. I’m no chemist, but here’s what I have come up with experimentally as a dryhop substitute:

Add 14g everclear and .5 ml 85% phosphoric acid to a French Press. Add 14g leaf hops and 500mL filtered water at 70C. Use the plunger to keep the hops from floating above the liquid. Allow to cool and combine with the priming sugar before bottling.

I don’t have any objective way to quantify it, but subjectively the acid eliminates the grassy flavor and the ethanol kicks up the efficiency. It’s like a dry hop on steroids, 400% or better.

I used to use beer, but it cheesed me off to waste beer. It’s funny, when I went to the liquor store to buy the dusty everclear bottle the clerk looked at me and said “You’re not going to drink that, are you?”.
 
Wynne-R said:
Nobody’s mentioned pH. I’m no chemist, but here’s what I have come up with experimentally as a dryhop substitute:

Add 14g everclear and .5 ml 85% phosphoric acid to a French Press. Add 14g leaf hops and 500mL filtered water at 70C. Use the plunger to keep the hops from floating above the liquid. Allow to cool and combine with the priming sugar before bottling.

I don’t have any objective way to quantify it, but subjectively the acid eliminates the grassy flavor and the ethanol kicks up the efficiency. It’s like a dry hop on steroids, 400% or better.

I used to use beer, but it cheesed me off to waste beer. It’s funny, when I went to the liquor store to buy the dusty everclear bottle the clerk looked at me and said “You’re not going to drink that, are you?”.
Click to expand...

What's the phosphoric acid do?

--Adam Selene
 
I do extractions of hop strains using ethanol and a nonpolar inert gas under a pressurized atmosphere to yield a beautiful hop extract used at the end of boiling.

20140126_104910-1.jpg
 
moorehops said:
I do extractions of hop strains using ethanol and a nonpolar inert gas under a pressurized atmosphere to yield a beautiful hop extract used at the end of boiling.
Click to expand...

Does this process require expensive specialized equipment or is it feasible for your average homebrewer to pull it off themselves? Could you elaborate a little on what the process involves if it is something we might be capable of doing at home? Thanks.
 
yes it does require special equipment, but it isnt expensive. the extraction process ive been using is unique and of my own design, Id love to go into details but I've spent the last 4 months perfecting the process.
I will however disclose the essentials behind a very easy home extraction!
It is not as efficient as my method, but it is very close and will still provide a phenomenal extract.
First you need 190 everclear alcohol or 151 proof. The higher the proof the better, stick with drinking alcohol to keep food quality. I stick the ethanol in the freezer into an salted ice bath to get the temperature well below freezing. The hops I'm extractimg from are also kept in the freezer. Freezing the hops ties up the chlorophyll and the other water solubles.
Next the two are mixed into a mason jar and shaken hard for 1-2 minutes and returned to the freezer for the next two minutes. Remove from freezer, shake the mix hard one last time then strain through a coffee filter into a baking dish.
Let the baking dish sit out and the alcohol will evaporate leaving behind your hop extract. Scrape with a razor blade and collect on to silicon sheet or parchment paper.
 
if your extract has turned green you've left it in the alcohol too long and its extracting chloryphyll and plant waxes. If kept under 3 minutes total contact time with frozen material, The extract should be anywhere from bright yellow to a warm amber. You will have extracted 70-80 percent of the lupulin glands free of any chlorophyll and non aromatic plant waxes.
 
Thanks! Ive never used pellets as my normal extraction using my non polar gas is much more efficient with whole hops. Although I imagine it would work fine if subtituted for whole leaf. Although filtering may be a bummer if the pellets turn to mush.
 
I use 70% EtOH, as can no longer buy grain alcohol here. I originally used it to increase the "hoppiness" of commercial beers, but found it works reasonably well with homebrews which turned out to be underhopped. One problem is that once the extract hits water(beer), some organics precipitate out. If you try this with plain water, you will get an off-white powder, which I cannot analyze. It may be instructive to boil that powder at pH 5 or so.
 
Do you mean 70 proof or 70 percent alcohol. Cause I use 151 proof which is 75 percent alcohol when I've run out of 190 proof and I dont get a white powder...do you evaporate all the alcohol? Or are you just adding oil/alcohol into the beer. If you are your talking about the ouzo effect, when alcohol is mixed with water and it produces a milky white cloudy effect. google ouzo effect.
In order to produce a pure extract you need to evaporate all the alcohol and water. It works faster with high proof, but if you set it in front of a fan in a baking dish where it will be a thin film it will evaporate.
 

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