EBUs - which is correct?

[pumblechook]

Currently mashing top dog stout in GWs brew your own book.

Making a 19l batch

The recipe calls for 17g challenger hops at start of boil. No problem, got plenty.

However, this brew is meant to come out at 40 EBUs.

Ive cross checked based on the calculation on page 22 of the book:

based on alpha acid of 7.6 - as per hop packet and as per the alpha acid table in the book, and factoring in hop utilisation of 24.7 I get a totally different quantity of hops... About 40g.

As its more than double the quantity in the recipe I'm slightly alarmed. Which is correct? I have about 60 mins to decide. Any ideas chaps?

Here are my workings:

40 x 10 x 19 = 7600. this is EBUs x 10 x 19 l brew length
7. 6 x 24.7 = approx 188. This is AA of hops x hop utilisation.

This gives

7600 / 188 = 40g Approx

Cheers

[pumblechook]

P.s, compared to other brews I've made, the 40 g calculation looks a lot more like it. I think 17g is a mistake. I will happily be corrected though!

[killer]

Brewmate agrees with you... I've just plugged those values in and it came up with the same answer as you.

[pumblechook]

Great, thanks for the quick reply. I'll go with 40g. I prefer bitter beers so would have been very disappointed if I'd went with 17g!

[Dave S]

I s'pose it depends on what the AA% age was when Graham compiled the recipe. Maybe it was a high yield year, though that's quite a difference. I've got some Fuggles and EKG at the moment with a stated AA of around 6.5%, compared with typical values for these of more like 4.5-5%.

[pumblechook]

That's what I thought Dave!

There is a chart in the book stating various hops and their standard AA. You would think it would make sense to standardise the recipes to that chart. I reckon it's just a mistake, we all make em.

I suppose the hops might be right but the expected EBUs stated in the recipe could be wrong. However, given the gravity, it would make sense for the EBUs to be on the bitter end to balance it out a bit.

Fingers crossed I've not got it wrong. Boiling away at the moment... Smells lovely!