Effects of Maillard and Caramelization Products on Oxidative Reactions in Lager Beer

The effect of colored caramelization products and Maillard compounds (melanoidins) on the oxidative stability of beer was evaluated by mixing lager beer with either caramel color (class III) or a dark beer (stout). Addition of caramel color or stout reduced the lag phase for formation of radicals in the lager as measured by spin trapping and electron spin resonance (ESR) spectroscopy. The level of sulfite decreased only slightly with the addition of caramel color and stout. Caramel color increased the level of radicals in a model system in which radical formation was initiated by the Fenton reaction. Stout decreased the level of radicals in this system, but not as much as lager. Prooxidative effects of caramel color and stout were observed in a storage experiment in which a lager beer and two beers made by mixing lager with either stout or caramel color were stored at 30°C in the dark. The ESR lag phase of the beers decreased linearly with time and with almost identical rates during storage, whereas the levels of sulfite decreased exponentially.