Are the major antioxidants derived from soy protein and fructo-oligosaccharides model systems colored aqueous soluble or insoluble compounds?

9 páginas, 6 figuras, 1 tabla.The present research aimed to determine the overall antioxidant capacity of solid model glycation systems based on either defatted soy flour or soy protein isolate as protein sources and fructo-oligosaccharides (FOS). In addition, we try to gain insight into the physicochemical characteristic of the major neo-antioxidants generated during heating of the model systems. These compounds may be formed in thermally processed foods containing as ingredients both components soy proteins and FOS. Samples constituted by protein source and FOS alone were employed as controls. The Maillard reaction was induced by heating at 150 °C for 1 h. Formation of colored compounds was detected by measuring the absorbance at 420 nm wavelength. The overall antioxidant capacity of the samples was either directly measured by the QUENCHER (quick, easy, new, cheap and reproducible) approach concept adapted to the ORACFL assay or indirectly by summing the ORAC values obtained by analysis under ORACFL standard conditions of aqueous and ethanol fractions of the samples. The sets of data were compared. The relationship between browning and antioxidant capacity was investigated. All samples excepting unheated FOS showed antioxidant capacity. Data seem to indicate that the QUENCHER approach allowed to determine in a single step, the overall antioxidant capacity of FOS caramels and thermally processed glycation mixtures leading to significant compositional changes as results of the simultaneous occurrence of reactions, such as Maillard, caramelization and thermoxidation. Our results also suggested a major formation of aqueous-soluble colored antioxidants from caramelization and Maillard reactions.This research was funded by the COST Action 927 ‘‘Thermally Processed Foods: possible health implications’’, Ministerio de Ciencia e Innovación (projects AGL2008-2541/ALI, AGL2007- 63462/ALI) and CONSOLIDER INGENIO 2010 program (FUN-CFOOD CSD 2007-063).Peer reviewe

Carotenoids as a Source of Antioxidants in the Diet

Capítulo del libro Caroteids in Nature, que corresponde al volumen 79 de la serie Subcellular BiochemistryCarotenoids, widely distributed fat-soluble pigments, are responsible for the attractive colorations of several fruits and vegetables commonly present in our daily diet. They are particularly abundant in yellow-orange fruits (carrots, tomatoes, pumpkins, peppers, among others) and, although masked by chlorophylls, in dark green leafy vegetables. Several health benefits have been attributed to carotenoids or to foods rich in these pigments, by means of different mechanisms-of-action, including the role as provitamin A of almost 50 different carotenoids and the antioxidant activity that protects cells and tissues from damage of free radicals and singlet oxygen, providing enhancement of the immune function, protection from sunburn reactions and delaying the onset of certain types of cancer. Common food sources and the efficiency of the absorption of carotenoids, analytical approaches used for measurement of their antioxidant effect and an overview of some epidemiological studies that have been performed to assess the beneficial impact of carotenoids in human health are outlined in this chapter.Peer reviewe