Barley-to-Beer Flavor Stability Secrets Revealed Using Electron Paramagnetic Resonance (EPR) Technology

MBAA TQ https://doi.org/10.1094/TQ-59-2-0505-01​  | VIEW A​R​TICL​E
Robert T. Foster II. BrewOpt LLC Consultancy (retired from Coors Brewing Company), Golden, CO, USA​

Abstract
 
Barley breeding practices over the decades have developed new barley varieties that pass agronomic, malting, cost, and quality criteria that may be capable of fortuitously improving beer flavor and flavor stability. Advancements in electron paramagnetic resonance (EPR) methods, also called electron spin resonance (ESR), with additions of appropriate scavenging and spin trapping for free radicals, have coincidentally advanced the possibilities of predicting improvements in beer quality and flavor stability at the barley breeding level. EPR results showing both the propagation and disappearance rates of stable free-radical adducts in malt extract, wort, and beer flavor trial samples show directional improvements in malting, brewing, and potential beer flavor stability. A significant relationship between an EPR area under the curve (AUC) metric and an abuse test (6 days at 40°C) connects different beer types with different malt bills and brewing recipes, resulting in different flavor stabilities in a predictive manner. EPR methods can link barley to beer samples that also predict good beer flavor and flavor stability of new and existing malted barley varieties. Examples of different free-radical effects from barley varieties, steep-out moistures, malt modification levels, 6-row and 2-row malts, kilning regimes, flavor stability trials, and SO2 levels are shown. With more empirical EPR research data connecting barley breeding to finished malt to production of better flavor and flavor-stabilized beer, maltsters will better understand which malting practices control and extend beer shelf life.
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