Influence of Maillard reaction and temperature on functional, structure and bioactive properties of fish gelatin films

This study aims to assess the effect of heating temperatures on structure, physicochemical and antioxidant properties of fish gelatin films crosslinked by the temperature and/or with glucose by the Maillard reaction. Glucose was incorporated at a 0.5 glucose/lysine molar ratio into the fish gelatin film forming solutions. The products of the Maillard reaction were generated by heating the films during 24 h in a temperature range of 90-130 degrees C. An enhancement of some films properties was obtained after the induction of the Maillard reaction. Indeed, the water solubility and wettability were reduced. On the contrary, a rise of color intensity, UV-barrier property, radical scavenging activities and iron reducing effects was observed. These enhancements occurred also without glucose addition thanks to the heating treatment, but to a lesser extend. In addition, an increase of thermal stability due to structural changes was revealed by means of XRD, TGA and DSC analyses. As evidenced by the different experiments used for the determination of the antioxidant activity (DPPH center dot and ABTS free radicals scavenging activity, reducing power and beta-carotene bleaching inhibition) the antioxidant activity of films containing glucose displayed an optimum after being treated at 90 degrees C. On the contrary, it decreased or kept constant at higher temperatures, probably due to the degradation or further stages of Maillard reactions. Moreover, the thermal treatment alone (T >= 100 degrees C) can be a useful tool for enhancing the antioxidant activity of gelatin films. Finally, the Maillard reaction has a good potential to induce and generate bioactive compounds in gelatin films for food protection.