There has been some discussion on the recipes contained in the popular book Brewing Classic Styles written by John Palmer and Jamil Zainasheff.
Although considered a high integrity source of recipes for both All Grain and Extract there was debate in regards to the conversion of the Hop bill from Extract to All Grain and Hop utilization between both brewing styles. (Both recipe versions carry the same Hop Bill)
This thread hopes to clear up that confusion and continues on from here
From my research over the last few days I've found that when this book was first published (Circa 2007) all the Hop utilization formulas out there (Tinseth, Rager, Garetz etc) all relied to some extent on the Gravity of the brew in determining Hop Utilization. It was thought at the time a Higher Gravity brew required more Hops to achieve the same IBU figures as a low Gravity brew. In 2008 this was proven to be incorrect and was confirmed in a BBR Podcast by John Palmer
It was also tested an an IBU Gravity Experiment and results checked in a Labratory. here
I will also highlight that it has been acknowledged even Lab results using the spectrophotometric method may not paint the true picture when it comes to our human perception of IBU's and hop utilization. I came across another article written by John Palmer that highlights an experiment using "Fresh" hops and "Old Hops" The only difference in the beers was the Freshness of the Hops. One brewed with Fresh hops as compared to 12 month old hops that had been exposed to Oxygen. An experienced tasting Panel judged or perceived that the Fresh hopped beer had a much higher IBU than the other beer, however the Lab results reported that both Brews had the exact same IBU rating at 22 IBU's! Apparently lab testing uses some form of light spectrum analysis to determine IBU's. In the testing here the results of the machine measured the same, however in tasting that was not the perceived case.
I took from that that we ultimately have to let our taste buds decide. Machines too cant be relied upon AND secondly there are many many variables in Hop and IBU ratings we just can not control or replicate easily. We might get close but 2 brewers brewing the exact same recipe with differently sourced ingredients are highly unlikely to achieve the same result especially in regard to Hop utilisation / IBU figures.
So back on track to the book. Since 2007 when published the Recipes in BCS (nor the Hop formulas used) have been updated to reflect this and there was some confusion surrounding why the Hop bills between both methods were identical.
I wrote to both Jamil Zainasheff and John Palmer querying why. Both Authors were kind enough to reply. Which I will include below. John was most detailed and most importantly for all BIAB'ers on here has confirmed that the Recipes contained within the book BCS are originally All Grain Recipes They were later converted to Extract versions. (apparently from what I read 70% of US brewers brew from extract hence they were catering for their biggest market)
Thus any Hop utilization errors (If any) is going to be found in the Extract brews and not with the Original All Grain recipes.
So hope that is useful to you guys and if nothing else you read it here first!
Post #1 made 5 years ago
Last edited by bundy on 06 Nov 2014, 09:21, edited 4 times in total.
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