The behavior of sulfites in beer during fermentation and storage after packaging was studied using a high-performance liquid chromatographic-fluorescence detection method that was developed for determining aldehyde-bisulfite adducts. Free sulfite and acetaldehyde-bisulfite were detected in young beer during fermentation and in Japanese commercial beers, but the other aldehyde-bisulfites were not. Sulfite showed an extremely poor reactivity with trans-2-nonenal in beer and a beer model system. Acetaldehyde-bisulfite and free sulfite decreased during beer storage and inhibited the production of acetaldehyde, indicating that acetaldehyde-bisulfite and free sulfite are oxidized by free radical reactions during beer storage and inhibit the oxidation of the other beer components.