After reading the Zymurgy special edition on hops I decided to write a program that calculated hop bitterness. As it turns out a lot work has been done to estimate the total bitterness (IBU). I incorporated variables for time of each addition, quantity and percent alpha acid of hops, wort gravity and final boil volume. The kettle utilization rates (KUR) are from Tinseth's work. These KURs are for pellets. Your mileage may vary!
Since the IBU calculation requires OG and volume I decided it would be nice to calculate the mash efficiency. The weight of the sugars, or extract, in the wort is simply the OG * weight of water * wort volume. The mash efficiency is defined as the weight of the extract divided by the total weight of the grain.
For example, I brewed an IPA with 20 lbs. of pale malt and 1.5 lbs. of crystal for a total grain bill of 21.5 pounds. The boiler contained 11.5 gallons of wort at an OG of 1.058, an extract of 14.47 lbs. of sugars. 14.47 divided by 21.5 equals a yield of 67.31%. My actual numbers range from 65 to 69 percent.
The percent of alcohol by both weight and volume is also given by entering the terminal gravity (TG).
Click here to download BeerAna.zip. Need an unzipper? Try WinZip.
The software is fully functional and runs on Win 95® and NT®. It also features persistent data so that it will remember the numbers you used last time.
After a brew session I use the software to analyze the results and enter the values into my 'Brewers Log Sheet'. Just for fun, I plugged in the numbers from several national championship brew recipes to see what kind of efficiencies the were attaining. Guess what, some exceeded 100%! They got more sugar into the wort than the grain they started with. Hmmmm.