Impact of electron beam irradiation on fish gelatin film properties

•Fish gelatin film irradiated by electron beam accelerator.•Electron spin resonance analysis reveals the formation of free radical species after irradiation.•No modification of the crystallinity after irradiation.•Enhancement of thermal and mechanical properties of the film.•Slight increase in surface polarity as well as water vapour permeability.

The objective of this work was to display the effect of electron beam accelerator doses on properties of plasticized fish gelatin film. Electron spin resonance indicates free radical formation during irradiation, which might induce intermolecular cross-linking. Tensile strength for gelatin film significantly increases after irradiation (improved by 30% for 60 kGy). The vapour permeability is weakly affected by irradiation. Surface tension and its polar component increase significantly and are in accordance with the increase of wettability. So, irradiation may change the orientation of polar groups of gelatin at the film surface and crosslink the hydrophobic amino acids. No modification of the crystallinity of the film is observed. These findings suggest that if structure changes, it only occurs in the amorphous phase of the gelatin matrix. It is also observed that irradiation enhances the thermal stability of the gelatin film, by increasing the glass transition temperature and the degradation temperature.

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