It seemed as if all the pieces came together for us and exactly the right times. I had just finished a brown ale brewed at Jan’s and now was ready to go on my own but i needed equipment and I needed it built. My good friend Justin and I were talking and he already had a bunch of materials that were ready for us to brew as he previously made wine. The only ting we really needed in terms of big things to start was a brew kettle and a wort chiller amongst other things that add up, Like Co2 , and Pepsi kegs. I wont even begin to talk about the adventure of the gauges just yet. Anyway we found an old Labbatt 15.5 gallon keg and Justin knew some hillbilly welders that build hotrods and trailers that knew how to weld. The price, free beer when we finish making it, now thats America!! The top of the Keg was plasma cut out and we put a j-valve near the bottom with a screen to filter out the hops.
In another streak of good luck, Justin, who works for a developing company got word that an apartment needed new kitchen fixtures and the old, steel, ones that were in perfect condition were just going to be thrown away, so….we volunteered to take them off of there hands for no cost.
For our first beer on our own I grabbed a good crew of guys, Bryan Infante (www.cigarsinreviewinfante.wordpress.com ) and a good friend of mine, Justin Cassagrande, who is our brewery designer and builder and, he really likes beer. I decided that I would try and redo the brown ale that won us the award. The reason why its an issue to duplicate is because the first one we did was on-the-fly as Jan was brewing a milk stout at the same time. I decided mid-brew that I wanted to use some of the lactose and some of the malt color from the milk stout to deepen the SRM and also to add the creamy sweetness of the lactose used in the Milk Stout, The only issue was i used about a gallon or less of the milk stout and I had no real idea how much more malt and how much lactose to actually add. When I designed the recipe for this one, in all honesty i “wung” it again but this time i wrote it down. The Recipe is as follows
Until Recently, I didn’t understand the concept of Alpha Acid and IBU’s and when they needed to be put in the beer and for how long but there is a pretty simple explanation and formula.
Looks Complicated doesn’t it ? Well it really isn’t, here we go
The AAU/HBU measurement of a hop addition is determined by multiplying the amount of hops by the hops’ alpha acid. While AAU/HBU formulas are quite simple and are still used in homebrewing, they have limited value in determining overall bitterness because they don’t factor in length of boil and other important parameters.
IBU calculations are just as simple, much more accurate, and are adaptable to a wider range of brewing situations. However, to be able to meaningfully incorporate IBU figures into brewing, you need to know and understand the basic IBU formula: IBU = Hops x AA% xutilization / volume x 1.34
- Hops = the weight of hops in ounces
- AA% = alpha acid percent
- Utilization = the utilization percent
- Volume = the volume of the final batch in gallons
- 1.34 = a constant to convert measurement into US standards
Now for the utilization
Technically speaking, utilization is
The final variable in the IBU formula is utilization percentage. In a perfect world it would be nice to assume that all of the potential bitterness available from the hops is extracted into the finished beer, but unfortunately that is not the case. Many factors affect the amount of bitterness actually liberated, or isomerized, into the finished product. Some of the more common factors:
Length of Boil: The longer the hops are boiled, the more bitterness is extracted into the finished beer. This is generally good up to about 90 minutes, at which point the law of diminishing returns takes effect and less bitterness is extracted per unit of time. Conversely, late hop additions for flavor or aroma will contribute considerably less bitterness due to the reduced amount of boil time.
Intensity of Boil: Homebrewers using a mega-BTU outdoor cooker can virtually blast the enamel off a steel pot and will have a much more vigorous or intense boil than the homebrewer using an electric range. The more intense and turbulent the boil, the more hop bitterness is extracted.
Volume of Boil: The greater the volume of wort being boiled, the more effective the extraction of hop bitterness will be. Don’t confuse this with final wort volume in the IBU formula. For brewers with smaller brewpots who can only do a partial wort boil, it is important to realize that the reduced volume of the boil will reduce the extraction of the hops.
Specific Gravity of Wort: Dense, high-gravity worts with lots of dissolved sugars will reduce the ability of the wort to extract alpha acids in the boil. The purchase of a large-volume brewpot (seven gallons or greater) and the attendant accessories such as a high-output burner is even more appealing when you consider that a reduced wort volume combined with the increased gravity associated with only boiling a portion of the batch and then later topping off to final volume is a double whammy against effective hop bitterness extraction.
Quality of Hops: Old or stale hops will lose some of their alpha acid value. Also, pellet hops usually provide a slightly greater degree of utilization in the boil than their whole leaf counterparts of equal alpha acid value.
Fermentation: The use of a small-volume fermenter and a blow-off tube for the early stages of fermentation will result in a portion of the hop resins being “blown off” with the foam from the kraeusen. In addition, as the yeast flocculates out it will carry with it some of the isomerized bittering compounds.
While there are many published sources that provide specific figures for each of these factors along with involved calculations, utilization percentage can be estimated fairly well. When doing a full-wort boil of moderate gravity (1.045 to 1.055), with hops boiled for 60 minutes or more, assume a utilization of 30 percent.
You can make a pretty good estimate of how your own brewing conditions will affect utilization and modify the numbers accordingly. For example if you are unable to do a full-wort boil or the beer you are making is of a relatively strong gravity, then it would probably be safe to assume that the estimate can be factored down by 2 percent to 3 percent.
I say forget all that and stick with my earlier estimations of utilization for the Home brewer they seem to be pretty spot on , and I have not ran into problems yet.
For Example using the Brown Ale recipe we used .5 oz of cascade at 30 minutes boil time at 6.6% AA lets figure out the IBUS (IBU = Hops x AA% x utilization/ volume x 1.34) IBU=(.5 x 6.6 x 23 /10 x 1.34) = ( 3.3 x 23 / 13.4) = (75.9/13.4 ) = 5.66 IBU’s @ 30 minutes boil time.
Using this formula is very useful in planning when and what to put into your brew according to BJCP guidelines.