IBUs not adding up...

[Scrattajack]

Hi all,

I'm planning on brewing a recipe from Marc Ollosson's book later in the week and I've typed it up into Brewer's Friend for a play. The recipe is Woodham IPA Bitter and consists of 3.87 kg of pale malt and 205 g of Crystal. Hops are 65 g of Challenger (6.2% AA) at the start and 12 g of Goldings (5% AA) 15 minutes from the end. Bittering units is given as 32 (EBU).

However, typing this into BF gives IBU (Tinseth) of 49.74 and a BU/BG of 1.26. This doesn't sound like the "superbly well-balanced beer" in the description. Can anyone suggest where I'm going wrong? Do I adjust the hops down until I get it to 32 or is Brewer's Friend known for over-reporting?

Thanks.

 

[DavidDetroit]

Since I doubt you'd want to adjust your method of adding hops or batch size, trying fiddling around with "when" you add the hops.

 

[Cwrw666]

The hopping rates look about right for an IPA to me.
I'd suggest that the term `superbly well balanced beer' is a bit meaningless. Sounds like the kind of **** you find written on the back of beer bottles.

 

[MmmBeer]

Looking at that, my first thought is that it could be a typo in the book, it does happen. Playing with the numbers, the most likely explanation seems to be that he intended to type 45g of Challenger, which woould lead to somewhere near 32 IBU's and a BU:GU ratio of about 0.8.

 

[An Ankoù]

I don't know Marc Ollasson, but there are some brewers, me included, who follow Wheeler's recommendations (also Brewpaks) and ignore Tinseth for traditionally hopped beers. The formula is amount in grams= (length x required IBUs) / (2 x alpha acid content) and ignore late additions. If I want a 25 litre batch with 32 IBUs, I'd need 64.5g of hops with an alpha acid content of 6.2% What does Ollosson say about calculating bitterness?

 

[Scrattajack]

What does Ollosson say about calculating bitterness?

Not a lot, really. He points out that you can't just substitute hops weight for weight, you have to take into account the acid content. For instance, 80 g of Goldings with AA of 4% will have 28 EBUs whereas 80 g of Target with AA of 8.7% would provide 60 EBUs. Then there's a method to work out the new weight if the AA % does differ.

 

[An Ankoù]

Not a lot, really. He points out that you can't just substitute hops weight for weight, you have to take into account the acid content. For instance, 80 g of Goldings with AA of 4% will have 28 EBUs whereas 80 g of Target with AA of 8.7% would provide 60 EBUs. Then there's a method to work out the new weight if the AA % does differ.

Does he say what the method is?
Wheeler's objection, by the way, was that he was finding his beer under bittered following Tinseth. While it might work for commercial breweries it seems not to work on the small scale.
I found exactly the same before I had even read Wheeler's comments.

 

[Scrattajack]

Does he say what the method is?

weight of original hop x alpha acid of original hop divided by substitute hop alpha acid

 

[An Ankoù]

weight of original hop x alpha acid of original hop divided by substitute hop alpha acid

Fair 'nuff. So we still don't know his basic calculation. But I'll bet it's the Brewpaks one.

 

[Zephyr259]

Does he say what the method is?
Wheeler's objection, by the way, was that he was finding his beer under bittered following Tinseth. While it might work for commercial breweries it seems not to work on the small scale.
I found exactly the same before I had even read Wheeler's comments.

That's Interesting, over the years I've adjusted my palate to what the calculators say but I recently found it amusing that Orkney Corncrake is stated to be 25 IBU on their website but my clone (which is pretty spot on) calculates at 40 - 45 IBU depending on the iteration, and mine tastes a bit softer than the commercial one. Podcasts tend to back this up, anytime they've got beers tested they've come back way under the calculated IBUs, with the exception of a hopstand experiment were there was a load of bitterness extracted from the hot steep.

 

[Scrattajack]

But I'll bet it's the Brewpaks one.

He does thank them in the preface for providing the alpha acid figures on their packaging.

 

[chthon]

I agree with some comments here on Tinseth. I have the impression that it is only correct for a bittering charge of at least 50 minutes, and that later charges have much less influence on the bittering than the calculation would give. Even double the amount for a 30 minute boil seems to result in less bittering than what you would have at the amount for a 60 minute boil.

 

[Zephyr259]

I think he was interviewed on Experimental Brewing a while back and he admits that his formula is only really applicable to his set-up, I also think he did it all with leaf hops which is amusing since pellets are so much more common these days.