The Role of Free Radicals in Beer Oxidation. Hirotaka Kaneda, Yukinobu Kano, Toshihiko Osawa, Shunro Kawakishi, and Kohzo Kamada. J. Am. Soc. Brew. Chem. 47:0049, 1989.

The relationship between free radicals and the staling of beer was studied. Hydrogen peroxide was generated when beer was incubated at 60° C. When examined by electron spin resonance spectroscopic analysis, the hyperfine splitting constants of phenyl-tert-butylnitrone adducts of beer incubated at 60° C with H₂O₂ were close to those of beer without H₂O₂. The production of aldehydes and the degradation of isohumulones during the incubation of beer were accelerated by the addition of H₂O₂ or by irradiation with ?-rays. They were inhibited by the addition of ethylenediaminetetraacetic acid. It is suggested, therefore, that H₂O₂ generated during the incubation of beer could interact with the metals present to play an important role in radical reactions in beer.

Keywords: Beer oxidation, Degradation of isohumulones, Free radicals, Hydroxyl radicals, Production of aldehydes, Radical reactions