Pre-crosslinking with putrescine improves mechanical and thermal properties of alginate film

The effect of putrescine as a pre-crosslinking agent on the performance of alginate film was investigated in the study. Compared to film pre-crosslinked with calcium ions (SA film), elongation at break (EB) of alginate film was effectively improved with putrescine pre-crosslinking. Specifically, the EB level of film pre-crosslinked with 0.05 mM putrescine increased by 11.9 times. Alginate films pre-crosslinked with putrescine had lower levels of swelling degree and water solubility than SA film. Additionally, the thermodynamic analysis revealed that alginate film pre-crosslinked with putrescine had higher thermal stability than SA film. These effects could be related to the formation of hydrogen and electrovalent bonds between putrescine and alginate molecules, as indicated by the Fourier transform infrared spectroscopy. Collectively, putrescine has potential as a pre-crosslinking agent to improve the physical properties of alginate film, and expand its application for food packaging. • Putrescine pre-crosslinking markedly improved elongation at break of alginate film. • Alginate film pre-crosslinked with putrescine had high thermal stability. • Putrescine could form hydrogen and electrovalent bonds with alginate molecules. • Putrescine had the potential as a pre-crosslinking agent to prepare alginate films.