IBU's For Coopers tins

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Re: IBU's For Coopers tins

Postby emnpaul » Friday Mar 04, 2011 3:33 pm

Hi every body.

New to the forum. I feel privileged. Still just a K&K brewer but looking at partials soon.

I know this is digging up an old post but I was just wondering if any of you found an answer to why a brew would lose bitterness as it ferments?

I found this on the Coopers website. Not sure if it helps.

"Much of the bitterness is made up of surface active compounds - this is why the foam of a beer is more bitter than the beer itself. Also the main reason a more bitter beer displays better head retention.

Surface active compounds attach themselves to the krausen (foam) and become trapped in the crusty ring on the wall of the FV. Also adhere to the yeast falling out of suspension.

Some bitter compounds fall out of suspension as the pH of the brew drops to a certain level - this is known as their "isoelectric point"."]


As for the bitterness attaching itself to the krausen I can vouch for that personally. Try running a fingernail through the scum ring and touching it to your tongue and you'll see what I mean. I wouldn't reccomend this with an IPA or big stout though :mrgreen:
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Re: IBU's For Coopers tins

Postby earle » Friday Mar 04, 2011 3:47 pm

I have no idea but I wonder how important the answer is given the calculated IBU of a brew is different to the perceived IBU. For example two brews of identical calculated IBU will taste different depending on the malt sweet/hops bitter balance. The brew with more unfermented malt sugars will not taste as bitter as the sweetness balances the bitterness of the hops.

Given the above, I usually look at the calculated IBU and the balance to get in the ballpark, once I've tasted the beer future recipes can be adjusted to obtain the desired bitterness.
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Re: IBU's For Coopers tins

Postby emnpaul » Friday Mar 04, 2011 5:05 pm

I have no idea but I wonder how important the answer is given the calculated IBU of a brew is different to the perceived IBU. For example two brews of identical calculated IBU will taste different depending on the malt sweet/hops bitter balance.


Good point and I tend to agree.

The only practical aplplication I can think of would be if you had an analysis of a bottled product at say 30 IBU and wanted to clone it. When formulating a recipe would you allow a for certain amount of loss and compensate accordingly? But as you say you can always adjust furture recipes to get closer.
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Re: IBU's For Coopers tins

Postby rotten » Friday Mar 04, 2011 9:44 pm

If I was to go back to Kit and bits I would drop the anticipated bitterness of all of my brews. It's hard to balance bitterness without the malt backbone IMHO. I also found it hard to balance the sweetness of the malt with the bitterness, Purely speaking from the kit and bits perspective whilst learning the trade. Whilst they were better brews than kit and kilo, theyn weren't perfect. Others may have mastered the art better than I.
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Re: IBU's For Coopers tins

Postby emnpaul » Sunday Mar 06, 2011 12:00 pm

Cheers and welcome !!


Thankyou Rotten.

Sorry, but I'm not entirely sure what you mean when you say "drop back the anticipated bitterness of my brews"? Do you think I should be starting with lower bitterness kits than suggested when trying out a recipe? Or if trying to copy a beer/style using kits and bits, start a little lower than the BJCP guidelines to achieve something closer to style, bearing in mind that some bitterness will be lost during ferment?

With "malt backbone" do you mean backbone of the mash variety?

Also my appologies for starting something with this loss of bitterness thingy again, as I made my original post in order to help clarify the issue for those that may have contributed or be interested in a definitive answer (which I realised I did not provide, but maybe edged a little closer?). :?: :?

I do have a question or two but I will try to post them on the relevant thread/s.

Thanks,
Paul.
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Re: IBU's For Coopers tins

Postby rotten » Sunday Mar 06, 2011 1:58 pm

G'day mate. I'm going to let a more experienced brewer explain my ramblings so I don't confuse you any more (hopefully). I like to think I know more than I do late at night, when actually I don't know much at all. Simply put though, below is a list of calculated tin IBU. You don't have to use a lower IBU tin as such, but as soon as you start adding dried malt, partial boils and hops, this will adjust the IBU. I only did a few brews like this so really not experienced enough to be giving advice. Have a look around for kit and bit questions, or partials, should be plenty of info.

Anna wrote:Ok then - here we go! (However, I'm still puzzled by Coopers' claim that IBU drops 10-30% during fermentation. Some of the software around will need revising if that is not the case. :? )

Using the formula: IBU of tin*1.7/23

Beer = IBU on can = IBU (based on 23L)
Lager = 390 = 28.8
Draught = 420 = 31.0
Dark Ale = 590 = 43.6
Real Ale = 560 = 41.4
Stout = 710 = 52.5
Pale Ale = 340 = 25.1
Mex Cerveza = 270 = 20.0
Can Blonde = 420 = 31.0
English Bitter = 590 = 43.6
Euro Lager = 340 = 25.1
Heritage Lager = 390 = 28.8
IPA = 710 = 52.5
Irish Stout = 560 = 41.4
Aust Bitter = 495 = 36.6
Pilsner = 420 = 31.0
Sparkling Ale = 490 = 36.2
Trad Draught = 420 = 31.0
Wheat Beer = 300 = 22.2

Yes, I'm bored at work again!

Anna (Sorry, can't get the table to tabulate properly - it looks OK when I type it! :evil: )
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Re: IBU's For Coopers tins

Postby warra48 » Sunday Mar 06, 2011 2:24 pm

Just to add to the good information posted by Rotten about the IBU of tins.

Basically, flavour in beer comes from only a few things, including mainly, but not only:
1. Malt (I'm keeping it simple, so I'm not breaking that up into its various components) but it includes flavour components of different types and strains of grain and residual unfermented sugars.
2. Hops
3. Yeast
Now, there are others but they are not important in this discussion for now.

One aspect we look for in beer is balance within the particular style.
Thus, if we have a beer with a starting of gravity of say 1.040, a good level of balancing hop bitterness is, say, in the region of about 30 IBU.
However, if we start with 1.060, that beer will comfortably support hop bitterness in the region of 45 IBU.
The balance of those two beers is similar, even though the figures vary.
Of course, it's complicated by how well the brew ferments and the finishing gravity. A lower finishing gravity will make the same level of bitterness stand out more than a brew with a higher finishing gravity.
So, it's all about your perception of bitterness for your brew and your taste.
How you like your beer is a personal thing, and with experience you will learn to tailor them to your taste. Experiment, keep notes, and make changes as you feel you wish to get to a beer you like.
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Re: IBU's For Coopers tins

Postby emnpaul » Sunday Mar 06, 2011 4:38 pm

Thankyou.

I know what you mean about balance and gravities etc. Just got the impression I had missed something obvious, which tends to happen around here.
I think I'm starting to get a grip on the tailoring to taste that Warra is talking about.

Regards
Paul
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Re: IBU's For Coopers tins

Postby Oliver » Thursday Dec 08, 2011 11:44 am

At the risk of starting something, I was just reading about Danstar Nottingham Ale yeast and noticed the following comment, which reminded me of discussions in this thread about whether fermentation reduces bitterness:
Because of flocculation, it may tend to slightly reduce hop bitter levels.

That seems to suggest that highly flocculant yeasts can reduce a beer's bitterness. How, I don't know but one would assume that it's something to do with the flocculating yeast attaching itself to some of the hop acids.

I'm sure there are greater minds than mine that will have some thoughts :-)

However, it sure doesn't suggest the 10-30 per cent drop in IBUs that Coopers has apparently claimed occurs during fermentation ...

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IBU's For Coopers tins

Postby bullfrog » Friday Dec 09, 2011 5:11 am

Can't speak as to the science behind it, but I've definitely noticed that Nottingham certainly washes out a lot of hop flavour and aroma, and that it finishes with a more subdued (perceived?) bitterness.
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