Crosslinking of a Gelatin Solutions Induced by Pulsed Electrical Discharges in Solutions

This study uses discharges in solutions for the treatment of gelatin solutions in order to generate crosslinking. The effects of plasma on the properties of gelatin solutions were investigated, the latter including viscosity, amino acid contents, chemical analyses, and gel strengths. The results show that, after short duration plasma treatments (5-10 min), the viscosity of the gelatin solutions increased, while the concentration of OH free radicals decreased. After adding ethanol to the gelatin solutions, a greater increase in viscosity, and a greater decrease in free radicals were found. This suggests that ethanol provides more free radicals that can promote the crosslinking of the gelatin solution during the plasma treatment, resulting in higher viscosity. The gel strength of the gelatin was greatly enhanced by the plasma treatment of the solution. The results regarding the free amino acid contents showed that the crosslinking degree of plasma-treated gelatin was higher than that of the untreated gelatin. FTIR measurements show that after plasma treatment, the IR bands at 1668 and 1558cm(-1), corresponding to the amide I and II groups of gelatin, shifted to higher wavenumbers, i.e. 1672 and 1564cm(-1), respectively. This suggests that crosslinking has occurred between gelatin molecules. The results show that discharges in solutions may be able to induce crosslinking reactions in the gelatin. Electrical discharges in solutions can be chemical-free, alternative crosslinking methods.