I'll start with a list of their kits, that details the concentrated colour and bitterness levels for each kit and also what yeast it comes with, and then go on to explain the formula used to work out the actual colour and bitterness of a particular kit modification.
Original Series Range:
Dark Ale - 650 EBC - 590 IBU - Ale Yeast
Draught - 130 EBC - 420 IBU - Ale Yeast
Lager - 90 EBC - 390 IBU - Ale Yeast
Real Ale - 230 EBC - 560 IBU - Ale Yeast
Stout - 1800 EBC - 710 IBU - Ale Yeast
International Series Range:
Australian Pale Ale - 90 EBC - 340 IBU - Ale/Lager Yeast
Canadian Blonde - 70 EBC - 420 IBU - Ale Yeast
English Bitter - 420 EBC - 620 IBU - Ale Yeast
European Lager - 90 EBC - 340 IBU - Lager Yeast (commercially available strain)
Mexican Cerveza - 53 EBC - 270 IBU - Ale/Lager Yeast
Thomas Coopers Selection Range:
Australian Bitter - 70 EBC - 495 IBU - Ale/Lager Yeast
Heritage Lager - 90 EBC - 390 IBU - Ale/Lager Yeast
India Pale Ale - 230 EBC - 710 IBU - Ale Yeast
Irish Stout - 1500 EBC - 560 IBU - Ale Yeast (commercially available strain)
Pilsener - 70 EBC - 420 IBU - Lager Yeast (commercially available strain)
Sparkling Ale - 90 EBC - 490 IBU - Ale/Lager Yeast
Traditional Draught - 130 EBC - 420 IBU - Ale/Lager Yeast
Wheat Beer - 65 EBC - 300 IBU - Ale Yeast (commercially available strain)
Apart from the Irish Stout & Wheat Beer kits that come with an unknown commercially available ale yeast, any other kit that just states 'Ale Yeast' or the Ale part of the 'Ale/Lager Yeast' is Coopers own dry strain that was developed in-house and is propagated under contract. Any other kit that uses 'Lager Yeast' in any way, is also an unknown commercial lager yeast.
Here is the formula for working out those concentrated colour and bitterness figures for a chosen brewlength.
The above figures are per/kg of kit extract, so if we are working out the bitterness for a 23L Dark Ale brew, we have to multiply 590 (IBU) x 1.7 (kg), and then divide this by 23 (L) to give the IBU of the kit once it's diluted to 23L -
590 × 1.7 = 1003 ÷ 23 = 43.6 IBU
This figure will reduce slightly, depending on what fermentables you then decide to add to the kit. To get a fairly accurate figure for this, I use Graham Wheelers Beer Engine software.
I start by setting the brewlength to my planned brew, then add 1.7kg of LME to represent the kit and then add a hop and bitter to achieve the bitterness level from the formula above. After this I add my chosen fermentables that will lower the IBU accordingly, and then add my hop additions to complete the recipe.
The results that I have had from this process have been a lot more consistent and balanced than my old hit and hope technique.
Sorry for waffling on a bit, but hopefully this may help some new and experienced kit modders.
BTW, I don't work for Coopers, they are just kind enough to supply us brewers with this great data
Cheers
MB
, if it says less than 2 weeks ignore it, as a rule of thumb 2 weeks will just about always give you a good beer if all else is equal.