Determination of Hydrogen Peroxide in Beer and its Role in Beer Oxidation

We have previously reported that the hydroxyl radical (OH radical) was generated after a definite period in the early stage of the beer oxidative process with an oxidative forcing test, which we called the “lag time” of OH-radical generation. It was considered that the lag time of OH-radical generation was related to an endogenous antioxidant activity of beer (EA value) which correlated with beer flavor stability. In our proposed mechanism of beer oxidative staling, it was speculated that the lag time of OH-radical generation (EA value) might correspond to a certain time period necessary to generate or accumulate hydrogen peroxide (H2O2) in beer oxidation processes. To clarify this hypothesis, a rapid, selective, and highly sensitive method for measuring H2O2 in beer was developed using flow injection analysis with a chemiluminescence detector. By monitoring in detail the progress of H2O2 generation during the oxidative forcing test with the developed method, H2O2 was detected after a definite lag period from starting the oxidative forcing test. The progress patterns of H2O2 detected resembled those of OH-radical generation in the corresponding beer. These findings demonstrated that H2O2 generation significantly correlated with the lag time of OH-radical generation (EA value) of beer. These results strongly support the hypothesis that the OH radical was generated via H2O2.