Photosensitizer Activity of Model Melanoidins

Abstract

This study investigates the potential of melanoidins, the brown pigments formed during Maillard reaction in thermally processed foods, to act as photosensitizers. Seven model melanoidins obtained from different amino and carbonyl compounds were irradiated in a photoreactor or exposed to sunlight. Changes in the ultraviolet−visible spectra and photobleaching were registered in all studied melanoidin systems, and reactive oxygen species were quantified. The data suggest a UV-A-dependent production of singlet oxygen via type II photoreaction and low levels of superoxide radical via type I reaction. The significance of these melanoidin-bound photosensitizers for food stability and quality is discussed. Keywords: Melanoidins; Maillard reaction; photosensitizers; singlet oxygen; superoxide radical; hydroperoxides; photobleaching