Isomerized hop extract

[krockett]

I'm making a Pliny the Elder clone which calls for hop extract to be added at the start of the boil. I just received my isomerized hop extract and all it says on the label is 'DO NOT BOIL'!

Anyone experience of using this stuff? Wouldnt seem right be be adding it after fermentation..

[oblivious]

If its pre isomerized it maybe for post boil correction additions


But I though a lot of the home-brew hop extract was not supposed to be very good

[robotmonkey]

Isomerised hop extract is different to just hop extract.

• Hop extract - oils extracted from hops (usually via CO2)
• Isomerised hop extract - hop oils that have essentially already been through a boil and can be added post fermentation to tweak bitterness

[krockett]

I'm tempted still to boil this to stick to the recipe - maybe it says dont boil cos you dont have to boil it.

Anyone got experience/ knowledge on this, whether I'll mess the brew up if I do it?

Thanks,

[robotmonkey]

I can't see it causing any harm. Only point I'd make is that it will add the same IBUs to the recipe whether you add it at the beginning of the boil or at the end.

[pob]

Without looking at or using it; if it says Do Not Boil, don't.

You may need another product. The boil will change/convert/damage it. The resulting flavours may throw the balance off, v expensive mess if it's a full Pliny hop load.

There may be another extract suitable for the boil, eg non isomerized extract.

[Frequent Sequence]

I have used isohop extract on a pliney clone with success.
I Just added it at flame out. You can wait and add it post fermentation if you want.

[Will_D]

This is one of the questions I meant to ask at BrewCon:

What IS isomerised hop extract?

Isomers:
A definition in Chemistry:
Each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties.

So its a stereo chemistry difference ( see cis and trans) whereby the same chemical has a different 3d shape.

Why is this important? Because in certain enzyme related reactions the shape of the molecule (or part thereof) ONLY fits into a certain enzyme's active site.

Is this important in brewing? I wish I knew!!

[Frequent Sequence]

Humulone the main α-acid found in hops is transformed (isomerized) by high temperatures into iso α-lupulic acid (iso α-acid)
Iso α-acids are much more soluble and have a greater antimicrobial effect.

An IBU is a measurement of iso α-acid in solution an IBU is represents 1 mg of isomerized alpha acid in 1 liter of beer. not accounting for beta acids.

therefore iso α-acid is important because it provides bitterness and antimicrobial properties.

[djanto]

some kits come with hop extract and it is added just before pitching the yeast

[Frequent Sequence]

some kits come with hop extract and it is added just before pitching the yeast

Yep that is isomerized hop extract. No boiling needed.

[Sorcerers Apprentice]

Isomerisation of hops happens in the kettle during the Boil,  but has only 30 -50% efficiency. Pre isomerised hops are used commercially to increase the efficiency of hop usage. The hops can then be used in the brewing process as pellets or liquid. Pre Isomerised hops are divided into two main categories
Pre-Isomerised Kettle Extract (IKE) which are added to the kettle to be boiled
These can be further categorised as:
Isomerised pellet hops (Iso hops)
Magnesium oxide Isomerised Hops (Mike)
Potassium form Isomerised hops (Pike)

Then there is another category of processed hops which are used downstream post fermentation, these are known as ISO hops. The fermentation process removes some of the hop bittering from the beer, by adding iso hops post fermentation this eliminates these losses. They are also used to improve beer foam, and have a very high utilisation rate but are expensive. Some can also be used to eliminate the impact of uv light on taste (Skunk) they are used by breweries wishing to use clear or green coloured bottles. (Some Mexican breweries got around the light struck taste problem by hiding it with a lime stuck in the top of the bottle 😁simple and very cost effective)
They have three main categories
Rho- standard foam stability
Tetra- uv light protection plus greater foam stability
Hexra- uv light protection plus standard foam stability

Hop oils can be added post fermentation to add aroma rather than bittering and are a seperate product.

Its a huge topic and many books are written on it some very technical. Tim O Rourke has published a readable article for further reading
http://www.ibdlearningzone.org.uk/article/show/pdf/501/

[krockett]

I ended up just bittering with Apollo and Columbus. Cant see how I'd have a use for the iso hop extract tbh.

[johnrm]

Add it to Bud.