HOMEBREW Digest #5744 Tue 28 September 2010


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Contents:
  IIPA IBUs (Kevin Eggemeyer)
  Iso-alpha acid solubility (fljohnson52)
  Re: IIPA IBUs (Joe Walts)
  Re:  IIPA IBUs ("jeff_ri")

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---------------------------------------------------------------------- Date: Mon, 27 Sep 2010 22:58:33 -0500 From: Kevin Eggemeyer <keggbrewer at gmail.com> Subject: IIPA IBUs In addition to the limit of how many IBU's you can get into a beer, there is also a limit to the sensory perception of bitterness. I have heard this limit stated as 65 IBUs, but have not tested this myself and had always believed the limit to be higher. Of course, this is only the perception limit for bitterness, not hop flavor/aroma. Kevin St. Charles, MO Return to table of contents
Date: Tue, 28 Sep 2010 7:11:27 -0400 From: <fljohnson52 at nc.rr.com> Subject: Iso-alpha acid solubility The maximum solubility of iso-alpha acids is not dependent on the maximum percent utilization of iso-alpha acids. If the maximum solubility is 90%, which I am not questioning, then one should be able to achieve this regardless of the efficiency of utilization. And it doesn't matter how one performs the additions. It is dependent on the properties of the solvent, temperature, and perhaps the concentration of other solutes. This list of factors is not exhaustive, but it doesn't include percent utilization. - -- Fred L Johnson Apex, North Carolina, USA Return to table of contents
Date: Tue, 28 Sep 2010 15:30:38 -0500 From: Joe Walts <jwalts at gmail.com> Subject: Re: IIPA IBUs For what it's worth, I built a saturation limit into my recipe spreadsheet. I don't have access to my formulas right now (I'm still in on a hospital computer, so I can't download anything), but you can view them here if you know how to trace formulas in Excel: https://sites.google.com/site/republicbrewpub/ The name of the file is Recipe_Gallons.xls. I believe my formulas follow the Tinseth model below 65 IBUs (modified to allow positive bitterness contributions of late kettle and whirlpool hops), and then linearly decrease the effectiveness of alpha acid additions so the projection passes near one of the Deschutes data points (80ish actual IBUs for a calculated 240ish IBUs?). I don't remember if I included a max IBU limiter, but the amount of hops needed to get to the Deschutes example would be absurd. I also did something with the Sierra Nevada hop school results that were printed in Zymurgy or BYO a short while back, but it may have just been a spot check of my calculations. Considering the massive dependence of hop utilization on brewing equipment and procedures, as well as the fact that perceived bitterness is only loosely correlated with IBUs (and has its own saturation limits), I'm comfortable with ballpark accuracy until it can be improved upon by better experimental data. Joe Madison, WI Return to table of contents
Date: Tue, 28 Sep 2010 20:10:47 -0400 From: "jeff_ri" <jeff_ri at cox.net> Subject: Re: IIPA IBUs Hi All, Interesting discussion in the last few HBDs about IBUs and solubility limits of alpha and iso-alpha acids. I've heard many times that the limit is "about 100 IBUs". I'm not sure of the source for this and definitely don't have references to back it up. However, I made an American barleywine many years ago that had a predicted 207 IBUs (Tinseth formula). It measured at 115 IBUs using the ASBC method and a 1:1 dilution with distilled water. The measurement was made about 13 months after pitching the yeast. FWIW, YMMV. Jeff McNally Tiverton, RI (652.2 miles, 90.0 deg) A.R. www.southshorebrewclub.org Return to table of contents
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