Brewing Conversion

[RedDragon]

I am about to do my first all grain brew using a recipe from Zainasheff and Palmer's book "Brewing Classic Styles"..the Extra Special Bitter. The recipe gives is basically for LME then gives the partial mash and all grain changes. I put the recipe into Beersmith for all grain and the total IBU is less than that of the original recipe (ie. 29.8 for the LME vs. 26.2 for the all grain). Should I adjust the hop amounts so that the same IBU levels are the same (ie if the 60 minute addition of Kent Goldings (5% AA) is 24.6 IBU for 1.2 oz.... the all grain additon should be 1.44 oz for the IBU to be around the same amound). Or should I just leave the recipe the same and just change the LME for the grain?

Thanks for your help!

 

[TheChemist]

That's entirely your call! If you like a bit more 'hop' to your beer, go for it. The taste threshold for bitterness is around 5IBU though, so I'd be really impressed if you noticed a difference between the two!

 

[Pappers_]

You've probably checked this, but have you adjusted the actual alpha acid % for the default ones in beersmith?

 

[RedDragon]

Yes, I checked the defaults.

 

[Yooper]

I just opened the book to that page, and I see that the first addition of EKG is 2 ounces, and an IBU of 39.8 is given, but in your post you say 29.8. I think he uses the Rager scale but I could be wrong.

 

[RedDragon]

Sorry, I meant the Special Bitter...pg119.

 

[Yooper]

I think that there are a couple of things going on. One is that I believe he uses a different IBU scale than I do. I use Tinseth. Secondly, when I punch that recipe into Beersmith, my numbers are different also. I thought that's because of my efficiency. My default is 72%, which gives me an OG of 1.055 and IBUs of 26.

Then, I went back and read "how to use these recipes" and he mentions that his recipes are designed to have 6 gallons finished in the kettle, with 5.5 gallons going to the fermenter so that you'll have 5 gallons of finished beer.

Aha! When I change the boil volume to 7 gallons with a finished volume of 5.5 gallons, my numbers match Jamil's more closely. I set my efficiency to 68%, and it seems like the numbers are then straight on. He said that he used Promash to formulate, with an efficiency of 70%.

 

[RedDragon]

Yes, my calcs came back more accurate...he was using the Rager scale. When I changed that in Beersmith, it matched pretty close.