Abstract

The aim was to study if the antimicrobial activity of chitosan incorporated into edible films based on gelatin could be affected by the molecular mobility (glassy or rubbery state) of the matrix. Films were obtained from film-forming suspensions (FFS) of bovine and salmon gelatins (7% w/w) and chitosan (0; 0.25; 0.5; 1% w/w) equilibrated at 33% y 85% of relative humidities. Antimicrobial properties against Escherichia coli, Listeria monocytogenes and Salmonella thyphimurium were determined. The results showed that both FFS and films had antimicrobial effects related to chitosan concentration. This besides depended on their glass and rubber film state, being in the initially glassy state for salmon 66% higher than bovine in comparison to the rubbery state (8%). This was mainly due to the highest moisture uptake (1.82±0.02% water absorbed/min) for glassy state. Therefore, the molecular mobility of the matrix film affected the antimicrobial activity of chitosan in chitosan-gelatin films.

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