Laura Marques (1), Maydelin Hernandez Espinosa, and William Andrews, Molson Technical Center, Molson Coors Brewing Company, Toronto, Canada; and Robert T. Foster II, Corporate Brewing, Malt, and Materials Department, MillerCoors LLC, Golden, CO, U.S.A. J. Am. Soc. Brew. Chem. 75(1):35-40, 2017.
Three different electron paramagnetic resonance (EPR) metrics—lag time, T150, and area—were compared with sensory data from two forced beer aging methods. Three types of beers were evaluated, namely, 1) standard lager, 5% alcohol by volume (ABV) and 3.30° standard reference method (SRM) color; 2) low-alcohol lager, 3% ABV and 2.20° SRM color; and 3) standard ale, 5% ABV and 4.00° SRM color. The two accelerated aging time–temperature treatments evaluated in this study were 18 days at 27°C and six days at 40°C, both being equivalent sensory-wise to our standard flavor stability staling rate of six months at 20°C. A significant relationship between EPR area and sensory staleness scores was found using the 40°C for six days temperature abuse treatment protocol (R2 = 0.9209–0.9567), not the 27°C for 18 days abuse treatment protocol (R2 = 0.0319–0.2046). In addition, the area under the curve metric displayed significant correlation coefficients (R2 = 0.9209–0.9567) with the 40°C for six days abuse treatment staling scores, whereas the traditional lag time and T150 values were not significant (R2 = 0.0174–0.2238 and 0.1010–0.8565, respectively). Using this analytical and sensory chemometric-style approach, subsequent brewing materials and process changes were made in the brewing process to lower the EPR area values in five breweries spanning three years of profiling. This resulted in improved packaged beer flavor stability. Using the connection between these novel, rapid methods, this study also highlights three causative beer conditions that have traditionally shown major impacts on flavor stability: namely, trace metals (Cu and Fe), dissolved oxygen, and bisulfite (SO2) levels. Using the EPR area metric, which represents the total amount of free radicals generated during the beer sample analysis time, led the way to engage a rapid forced beer sensory method. Once employed, longer packaged beer shelf-life improvements over the three-year period were realized. This new dynamic program is currently being used in our breweries.