CO2 Hop Extract

[MFigz]

I brewed a cream ale recipe last weekend, and I misread the recipe and forgot the 60 min bittering hop addition. The recipe only called for 20 IBU's anyways, and because I missed the 60 min addition I will be more like 6 IBU's. Since it's a Cream Ale, it's not supposed to be very bitter in the first place but I tend towards more bitter beers anyways, so I had a thought.

If I were to boil some C02 Hop Extract in a known volume of water for 60 minutes to isomerize the AA, would that essentially allow me to adjust the bitterness post fermentation? Like I said, I'm not as concerned about this particular brew, but there have been plenty of times where I wish some of my IPA's had a little extra kick.

Can anyone think of a reason this wouldn't work?

Thanks,
Mike

 

[Vale71]

This will work, but:

- you'll have some dilution of your beer since you have to use enough water to avoid saturating the "extract tea"
- you won't have the faintest idea how many IBUs you're actually adding so you could easily end up with either too little or way too much

If you can get your hands on some pre-isomerized extract it would be the better alternative IMHO.

 

[MFigz]

The website says that One-milliliter yields around 10 IBUs in 5 gallons of 1.050 wort when boiled for 60 minutes. I figured if I were to boil 150 ml of water with 1.5 ml of extract, it should get me to around 20 IBU's and shouldn't dilute the beer much at all. You bring up a great point though, is 150 ml going to be enough to dilute the "tea" in.

I've never seen pre-isomerized extract, do you know of a brand or store where I can look into that?

Thanks!
Mike

 

[Vale71]

Your tea will have 20 IBUs (it will probably have even more) but tose will get diluted once you add that to the beer. Just multiply those 20 IBUs by 0.15/your_beer_volume_in_liters and you'll see how minuscule your actual addition will be.
As for the availability of pre-isomerized I'm sorry but I can't help you without knowing where you live. In some countries it's even illegal because of archaic laws...

 

[MFigz]

According to the product info, it sounds like 1 ml =10 ibu in 5 gallons. If I concentrate that onto a few hundred ml, wouldn't that make my hop tea super concentrated with ibu's, or am I missing something with the math?

Thanks!
Mike

 

[eric19312]

According to the product info, it sounds like 1 ml =10 ibu in 5 gallons. If I concentrate that onto a few hundred ml, wouldn't that make my hop tea super concentrated with ibu's, or am I missing something with the math?

Thanks!
Mike

Mike I think you are right. When I use extract I use about 3 ml in 17 gallons to give about 10 IBU. 1-2 ml boiled In a couple cups of water should get you some sig IBUs. You could also do a test. Make your isomerized hop tea, then add a measured amount to a sample of your beer. Then extrapolate to the full keg, increase or decrease based on the test.

 

[IslandLizard]

I figured if I were to boil 150 ml of water with 1.5 ml of extract, it should get me to around 20 IBU's and shouldn't dilute the beer much at all.

I think this is what you meant to say: "it should get me to around 20 IBU's for the whole batch".
Yes, that should work.

Now since you're boiling in plain water, there are no sugars present as in 1.050 wort, so isomerization reactions are much faster, and you may extract more bitterness. From what I've heard and read there is no real ceiling to how much bitterness (isomerized AAs) a solution can contain.

Keep an eye on the volume, 150ml evaporates in no time. Either keep topping up while it simmers, or start out with a higher volume of say 0.5 - 1 liter and let it concentrate as it simmers and evaporates during the hour. The volume you're ultimately adding to the keg is not as important. Even adding 250ml to a keg won't dilute it by much.

Please let us know how it went.

 

[Vale71]

According to the product info, it sounds like 1 ml =10 ibu in 5 gallons. If I concentrate that onto a few hundred ml, wouldn't that make my hop tea super concentrated with ibu's, or am I missing something with the math?

Thanks!
Mike

Can you post what brand and type of extract you have available? The reason I ask is because I have a nagging suspicion that what you have is indeed pre-isomerized.

 

[MFigz]

https://www.yakimavalleyhops.com/product_p/extractco2hopextractcans150-18.htm

 

[Vale71]

OK it's not isomerized.

As to hop utilization, there is unfortunately a limit to how much you can utilize in practice even using CO2 (non-isomerized) extract.

Alpha-acids first need to go into solution for heat to start working its magic and creating the permanently soluble isomers. Solubility of non-isomerized alpha-acids is limited and drops dramatically with decreasing PH. This gives you an advantage if you're using plain water as it will have a higher PH than wort. As alpha-acids become isomerized they free up space for more non-isomerized acids to go into solution and be isomerized themselves.

However, isomerization does not stop where and when we want it. As long as heat keeps being applied isomerized alpha-acids keep being turned into isomers that are progressively structurally more different to the original form. After a certain point alpha-acid isomers are created that do not have any more bittering capability, so that IBUs in wort can actually decrease if you grossly overdo the boiling. It's one of the reasons why in practice it's not meaningful to boil hops for longer than 70-80 minutes as utilization stops increasing at about that time.

Beyond a certain point you have a situation where the amount of isomers that lose their bittering power that are created equals the amount of desirable isomers that are being extracted from hops (either whole or extract). In practice this means that beers with more than about 100 IBUs are not feasible unless you use pre-isomerized extract. Pre-isomerized extract is isomerized using chemical catalysts that ensure almost 100% utilization and can be added up to their actual saturation limit, which is so high that nobody will be able to drink such a beer as it will be unbearably bitter.

If you're going to isomerize 1.5 ml of extract in only 150 ml of water and want to add 20 IBUs in a final volume of 5 gallons you'll have a dilution factor of about 125X which means that your hop tea will have to hold 20x125=2,500 IBUs which is completely unrealistic, even if using plain water. You could realistically reach maybe a couple of hundred IBUs which when diluted will hardly make a difference...

 

[eric19312]

Vale can you point at a source of pre isomerized extract? All the ones I found are in the UK for some reason.

 

[Vale71]

Here's one:

https://www.hoptech.com/products/iso-alpha-extract-2-oz

It's in Dublin but it's the Dublin closest to you, not the other one...

 

[IslandLizard]

As to hop utilization...

Thank you!
Always something to learn:

• There are limits to the amount of IBUs that can be generated with hops or hop extracts in a boil.
• Isomerization reactions are complex, generating different isomerates.
• Isomerates lose their bittering characteristics with extended boil times.

If you don't mind me asking, where did you source this information?

 

[Vale71]

From the proprietary material I got for my master brewer course.

I found this thesis that goes into detail (maybe a bit too much of it) about the kinetics of hop boiling and isomerization.

https://www.google.com/url?sa=t&rct...ds/bz60d000z&usg=AOvVaw2rKefD_Ri0UUGJoOsYUkKV

It's worth at least jumping to the very end where you'll find some experimental runs at temperatures ranging from 70°C to 130°C (boiling in a pressure vessel is quite common in large operations) clearly showing that, especially at the higher temperatures, the law of diminishing returns kicks in pretty quickly and the total-alpha concentrations actually start decreasing from a certain point onwards.

 

[IslandLizard]

Thank you, very appreciated! ^
Interesting reading.

 

[Vale71]

BTW if you get your hands on isomerized extract do not try and taste it in undiluted form. It won't be a pleasant experience as it is really unbelievably bitter.

One day I was feeling particularly brave and I picked up some extract with a disposable pipette. I then touched the tip of the pipette to the tip of my tongue withourt squeezing (I might be brave but I'm not stupid) letting capillarity deposit maybe a microliter or less of extract onto my taste buds. It wasn't unbearable but I still didn't care for the result...

Craft breweries that claim that their beers have 1000 IBUs or some incredibly high number are just spouting nonsense obviously. You can only get such high concentrations using isomerized extract and then nobody will be willing or even able to drink your beer.

 

[brewbama]

I had a wallflower beer that needed more bitterness once so I put an oz of Cascade flower hops in a quart jar, poured boiling water over them until they drank what they wanted and filled it the rest of the way. I let it sit an hour then drained the golden liquid into a sanitized jar and poured it into the keg. It made a pretty good beer. No idea what the IBUs were but it saved an otherwise super sweet dumper.