Abstract: In this study, the effect of cross-linking with different amounts of plasma amine oxidase (PAO) in the presence and absence of Cu2+ as a co-factor on gelatin structure and rheological properties was investigated. The results of sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the contents of large molecular mass bands in gelatin increased with increasing PAO level. Meantime, scanning electron microscopic (SEM) results revealed that the structure of gelatin became more compact with smaller empty space. The results of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy demonstrated that the network structure of gelatin was greatly affected by treatment with PAO and the best cross-linking effect was achieved with a PAO concentration of 50 U/g, as indicated by the largest number of large molecular mass components, the highest thermal stability and fluorescence intensity, and the denser and more orderly network structure. We found that 100 mmol/mL Cu2+ did not play a positive role in the cross-linking of gelatin. In view of the positive results above, this study provides a potential approach for crosslinking gelatin and other proteins.

Key words: gelatin; plasma amine oxidase; cross-linking