Characterization of ribose-induced crosslinking extension in gelatin films

Gelatin is a valuable protein for food and biomedical industries. However, gelatin-based products present moisture sensitivity which requires gelatin modification to change its functional properties. The addition of ribose into gelatin formulations (2.5, 3.5 and 5.0 w/v %) and subsequent film heating processes at 70 and 90 degrees C promoted the Maillard reaction with the aim of crosslinking gelatin to improve its properties. Crosslinking extension of the films prepared by casting was indirectly assessed through mass loss in water and color measurements, as well as ultraviolet-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopies. Samples with the highest gelatin content (5.0 w/v %) and heated at 90 degrees C (5.0HT-90) for 24 h showed the highest UV barrier properties, total color difference (Delta E*) and browning index (BI) values as well as the lowest mass loss percentage, indicating that a more extensive crosslinking reaction was induced in these systems at those processing conditions. Furthermore, a bigger conversion of alpha-helix structure into beta-sheet structure was observed by FTIR in 5.0HT-90 films. This study shows the possibility of controlling the extent of crosslinking by means of varying initial gelatin concentration, heating temperature and time to design films with tailored properties for food and biomedical applications.