Technological approach to improve beer flavor stability: Analysis of the effect of brewing processes on beer flavor stability by the electron spin resonance method

A novel electron spin resonance method for determining the endogenous antioxidant activity of beer, which is expressed as the lag time for OH-radical generation during the forcing test, has been successfully applied to study the effect of each brewing stage on beer flavor stability. OH-radical generation was determined in wort as well as in beer, but OH-radical generation in wort was detected immediately after the start of the forcing test with no lag time. The OH-radical generation activity, which was expressed as the quantity of OH-radical generation in wort at a 120-min forcing test, was defined as another novel index. By monitoring two indices in derail during each brewing stage, the effect of each brewing stage on beer flavor stability was analyzed. Based on the analytical results, the improvement of beer flavor stability by altering the conditions of some brewing stages was practically and efficiently achieved.