Potential antioxidants in beer assessed by ESR spin trapping

A number of potential antioxidants have been evaluated for their effect on formation of radicals in beer using the electron spin resonance (ESR) lag p hase method. Sulfite was found to be the only compound that was able to del ay the formation of radicals, whereas phenolic compounds such as phenolic a cids, catechin, epicatechin, and proanthocyanidin dimers had no effect on t he formation of radicals. Ascorbate, cystein, and cysteamin were on the oth er hand found to be prooxidants. It is suggested that antioxidants must be able to either scavenge peroxides or trap metal ions in order to be effecti ve in beer. The effectiveness of sulfite is suggested to be a consequence o f its two-electron nonradical producing reaction with peroxides.