Young, J., Blue Owl Brewing, Austin, TX, USA and Bochman, M. L., Indiana University, Bloomington, IN, USA
Technical Session 1: Omics
Sunday, June 04, 2017
10:15–11:30 a.m.
Caloosa Ballroom
Adding sourness to wort fundamentally changes one of the key elements in the flavor profile. Wort souring is being used by many breweries—from nano to nationally distributed production breweries. Studies are being conducted using DNA sequencing to determine the species and relative abundance of barley and grain-soured wort bacteria, as well as NMR analysis to determine the alcohol/organic acid wort profile. Results will help us better understand and utilize naturally occurring bacteria found on malted barley for the purposes of wort souring. The results of these studies will be presented, and the topics include 1) mapping the native microbiome on freshly malted barley from multiple sources (3 different continents; 2 different malting facilities with the same barely); 2) tracking the growth of bacteria in wort after being inoculated with the malt; 3) assessing the organic acid composition in the wort, post-souring; and 4) practical brewing consideration in reference to the dominant souring bacteria determined in #2 (wort clarity and fining, yeast selection and harvesting [a study done with Kara Taylor from White Labs will give details on harvesting yeast from wort-soured beers], and beer fining). DNA sequencing was conducted on pilsner malt, as well as wort soured with the malt to determine the species and relative quantity of bacteria, wild yeast, molds, etc. The malt was selected with the assistance of Bob Hansen, technical services manager of Briess Malting Co., and it was determined that pilsner malt was the most ideal malted barley to study. Freshly harvested 2016 barley malted at two different Briess malting plants was investigated to compare geographic variation in the malt microbiome. Additionally, fresh pilsner malt from Weyermann and ~6 month pilsner malt from Patagonia will be compared for the same purposes. DNA sequencing data will be presented to identify and quantify the thriving microbes in wort that is inoculated with the malt samples from #1, using conditions established by Jeff Young at Blue Owl Brewing. Soured wort samples were analyzed for composition of alcohols and organic acids using NMR assays by Dr. John Edwards of Process NMR Associates, LLC. The metabolites of the bacterial fermentation will help illuminate and correlate the activity of the dominant bacteria discovered from the DNA sequencing. All of the data collected from the DNA sequencing and NMR analyses will be related to how a professional brewery of any size can harness natural bacteria sourced from malted barely. Even though the source inoculant is easily accessible and practically free (Blue Owl spends less than $5 to sour 30 barrels of wort), the low pH, bacterial load, and high levels of acidity necessitate a reassessment of all steps of the brewing process—from wort turbidity to hop oils, yeast selection, harvesting, and fining.
Jeff Young has been brewing for over a decade and was previously an analytical chemist at a pharmaceutical company. Jeff’s passions for art, science, and engineering come together in the brewhouse! Jeff left his previous brewery, Black Star Co-op Pub and Brewery, to focus solely on sour-mashing and the novel, seemingly endless possibilities of integrating sourness in any beer style.
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