ASBC Methods of Analysis - Beer-46: Measurement of Oxidative Resistance in Beer by Electron Paramagnetic Resonance
ASBC Methods of Analysis
Measurement of Oxidative Resistance in Beer by Electron Paramagnetic Resonance
This method determines the oxidative resistance of beer. Electron paramagnetic resonance (EPR) spectroscopy is used to directly measure free radical production in the beer during a forced oxidation assay. The assay is based on an EPR-spin trapping experiment in which free radicals form covalently bound adducts with the (-phenyl-t-butylnitrone spin trapping reagent. The accumulation of these adducts is detected by EPR during the forced oxidation period and directly reflects the resistance (or lack of resistance) of the beer to oxidation. Two metrics obtained from the assay, lag time and EPR intensity at 150 min (T150) values, can be used to quantitatively assess a beer’s oxidative resistance.