Photosensitization reactions in food and model systems

C.D. BORSARELLI

San Miguel de Tucuman

Otro; COLOQUIO DE FOTOQUIMICA Y FOTOBIOLOGIA; 2006

DAAD-UNT

The natural combination of light, oxygen and dye molecules can be result in deleterious reactions in food systems, due to the formation of reactive oxygen species (ROS), such as singlet molecular oxygen (1O2) or anion superoxide (O2·-). These species are able to oxidize main food molecules producing off-flavour reactions. Many artificial and natural molecules can react efficiently with ROS avoiding the degradation of key molecules and preserving the food system (antioxidant effect). In the first part of this presentation, the photosensitized 1O2 – mediated oxidation of carotenoids1,2 (b-carotene and bixin), and flavonoids3 (naringin and its chalcone isomer)3 will be discussed, with special emphasis in the fate of the antioxidants and the type of oxidation products generated. Finally, the photoprotection mechanism of 1O2 – mediated oxidation of vitamins A and D in skim milk by a novel lycopene – gum arabic microcapsule will be presented. In this part the excited state interaction of the natural milk photosensitizer riboflavin (vitamin B2) with the microcapsule will be discussed.4 1 M.A. Montenegro, M.A. Nazareno, E.N. Durantini, C.D. Borsarelli, Photochem. Photobiol. 75, 353 (2002). 2 M.A. Montenegro, A.O. Ríos, M.A. Nazareno, A.Z. Mercadante, C.D. Borsarelli. J. Agric. Food Chem., 52, 367 (2004). 3M.A. Montenegro, M.A. Nazareno, C.D. Borsarelli. J. Photochem. Photobiol. A: Chem. In press (2006). 4 M.A. Montenegro, I.I. Nunes, A.Z. Mercadante, C.D. Borsarelli. Submitted to J. Agric. Food Chem. (2006).