The mechanism of stale flavour development in beer and ways to inhibit staling have long been of interest for the brewer. It is well known, that levels of oxygen in packed beer and shelf storage conditions are important factors in stale flavor development. It is also generally agreed that oxygen pickup and overall reducing potential through out the brewing process, including those Steps prior fermentation, may have a cumulative effect on flavor stability. There are naturally several substances in beer, that have a high reducing potential, to contribute to a better taste stability by reducing the occurrence of stale flavor. They can act by decreasing molecular oxygen levels, scavenging chain-initiating and chainpropagating
free radicals, chelating metals, decomposing peroxides, or changing of volatile aldehyds into non volatile substances. Sulphite, ascorbic acid, superoxiddismutase, phenols and many other compounds will contribute to a good flavor stability.

Reducing substances in beer