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Upping Bitterness With Isohop

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Stubbie

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Sampled a couple of newly tapped kegs this week and feel both could have done with a touch more bitterness. Maybe 3 or 4 IBU. So I was thinking of using Isohop to adjust the bitterness, probably by pouring a glass, adding the appropriate number of drops and returning the same to the keg.

Anyone used Isohop to increase the bitterness of a kegged beer and, if so, any advice?

One of the things I wonder about is whether the stuff will diffuse evenly rather than having little effect for the most part and then delivering a super bitter pint.

Stubbie
 

Thirsty Boy

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yes - you will find it hard to "add a number of drops to a glass" because isohop is so concentrated that even one drop will make a glass of beer essentially undrinkably bitter.

If you want to experiment, then put 2 or three drops into the bottom of a shot glass, and then add 10 times that many drops of water, stir it up and then drop the dilution into a glass of beer.

the other way to do it is just to crunch numbers. isohop is usually about 30% pure iso alpha acid. An ibu is (near enough to) 1ppm of alpha acid, so in 1kg of beer you have to add 1milligram of iso alpha acid to raise the bitterness by 1 ibu.

now its just arithmatic.

you want 3-4 ibus.... but really you cant taste an increment smaller than 5 ibus anyway, so lets say 5. so you need 5mg per liter and have say 20L so you need 100mg of iso alpha acid to get a 5 ibu increase in 20L. Now you'll need to check the concetration of the isohop you happen to have, but if its 30% alpha acid like the stuff i have... then that means you want to use 100/.3= 333mg or a third of a gram.

If you have scales able to measure accurately at that level, measure it out, dissolve it in 50ml of water and tip it in your keg. If you dont have scales able to measure down to 100th of a gram, then dilute 1 gram in 10g of water and measure out 3.3g of the dilution. If you dont have scales that are accurate enough to measure out a single gram properly.... then you are a time waster, get some. You beer isn't bitter enough because you cant even ******* measure your hops properly!

Iso alpha acids are soluable in water - just give the keg a good shake and that will distribute it and keep it that way. Taste to see if you've got what you want. I'd be inclined to shoot low to start with..... you can always add more but you cant take it out. And dont taste a whole bunch in one day. Taste, adjust, taste again later in teh day or tomorrow. It easy to blow you palate and end up with a beer that you'll try the next day and realise you overbittered.

It works just fine - but be careful, its strong stuff.

TB
 

Stubbie

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Good stuff TB,

Many thanks for your highly informative response. I'm all for crunching the numbers and having some sort of an understanding. And I just happen to have scales capable of measuring down to 0.01g and feel more confident weighing out a quantity than, say, counting drops as an approximation of a highly potent substance. As you pointed out, my biggest concern is overdoing it.

Stubbie
 

drsmurto

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As TB has pointed out, make a concentrated solution and then dilute by a factor of 10 or 100. This gives you greater control. The larger the initial mass you weigh out the smaller the relative error of measurement.

And no, I am not referring to a homeopathic dilution regime :p
 

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