Setting the Bitterness Formula in Beersmith

[Dicko]

Since brewing on a BM I have noticed that, when using my old recipes, the perceived bitterness is lower from brews on the BM.
I put this down to the less vigorous boil from the BM.

I was wondering from the brewers that use Beersmith what bitterness scale you have your software set to. Eg Rager or Tinseth.

There is a facility within the software to fine tune the bitterness as well.

What are others thoughts on this??

[piet_v]

Recently there has been some research into this.
Volumes brewed were typically 'homebrew' sized, so I guess relevant for us.


[q]Evaluation of international bittering unit calculations based on measurements of bitterness units via spectrophotometry and iso-?-acid concentrations via HPLC
BRETT F. TAUBMAN (1), Seth D. Cohen (1), Taylor Krivenki (1)
(1) Appalachian State University, Boone, NC[/q]

[q]While it is believed that hop ?-acids, once oxidized to hulupones, impart a minimal overall bitterness, it is the ?-acids, via isomerization to iso-?-acids during the boiling of wort with hops, that are the most important bittering constituents of hops. To determine the bitterness in a beer, the bitterness units (BUs) can be measured spectrophotometrically or the iso-?-acids can be quantified via HPLC analysis. However, most small- to medium-sized breweries do not have the laboratory facilities to measure BUs or iso-?-acids in their beers and determine overall bitterness. Rather, they rely on calculated estimates of the quantity of ?-acids that isomerize and dissolve into the beer, the international bittering units (IBUs). There are several equations that are used for calculating IBUs, the most common of which are those posed by Garetz, Rager, and Tinseth. The Rager method is the oldest and generally results in the highest IBU values. The Garetz formula takes into account more factors and typically results in the lowest overall IBUs, largely because short boil times are estimated to provide no utilization in the equation.
The Tinseth method is considered by many to be the most accurate, with IBU values that fall somewhere between the Rager and Garetz methods. However, no laboratory study has been conducted to determine which method is the most accurate and under what conditions, until now. Multiple small batches (20–80 L) of beer were brewed, varying different factors each time, including boil time, starting gravity, hop variety, hop addition (time and amount), hop type (pellet versus whole leaf), and yeast variety. The ?-acid concentrations of hops used in the study were measured using HPLC, and the IBUs were calculated using the three formulas based on the measured concentrations. The BUs of the finished beers were determined by isooctane extraction followed by spectrophotometric absorbance at 275 nm. The iso-?-acid content of the finished beers was also measured using HPLC. For the most part, BUs and iso-?-acid concentrations correlated well, although the measured iso-?-acid concentrations of beers made with hops that were locally grown in North Carolina were lower than expected. Interestingly, the measured BUs for most of the beers analyzed matched the Garetz calculation of IBUs most closely. This was particularly true for the beers brewed with North Carolina-grown hops, in which isomerization of the ?-acids appeared to be limited. The reason for the apparent limited isomerization of the ?-acids in North Carolina-grown hops will be explored further, and additional conditions will be tested to assess which IBU calculation is most accurate and under what conditions.[/q]

[q]Brett Taubman has been a faculty member of the A.R. Smith Department of Chemistry at Appalachian State University (ASU) since 2007 and is engaged in instruction and academic research within the chemistry and fermentation sciences. He has B.S. degrees in both finance and chemistry from the Pennsylvania State University and Montana State University, respectively, and a Ph.D. degree in analytical and environmental chemistry from the University of Maryland. Brett has successfully developed a pilot instructional brewing facility (Ivory Tower Brewery [ITB]) on the ASU campus and currently serves as president and head brewer of ITB, co-director of the Fermentation Sciences Program, and president of the High Country Beer Fest, an annual fundraiser for the program that showcases regionally crafted fermented foods and beverages.[/q]

[Dicko]

So basically from that article, Tinseth is the accepted formula for the home brewing situation?

Is this formula what most people use, or do you adjust hop utilisation percentages within the software?