Trans-Cinnamaldehyde-doped quadripartite biopolymeric films: Rheological behavior of film-forming solutions and biofunctional performance of films

Abstract

Biofunctional quadripartite films were developed by adding trans-Cinnamaldehyde (CIN) (0.4, 0.8, and 1.6% w/v) into chitosan (CH)/poly(vinyl alcohol) (PVA)/fish gelatin (FG) matrices. Rheological data revealed that all solutions exhibited shear-thinning and typical entangle polymers solutions behavior. Mechanical results showed that the incorporation of CIN caused a significant increase (p < 0.05) in tensile strength, while a significant decrease was observed in elongation-at-break. With increasing CIN content, the WVP of the films, which were in the range of 0.785–0.995 g mm/kPa h m2, increased to some extent, whereas the water solubility and water absorption were reduced up to 47 and 87%, respectively. Moreover, water contact angle analysis showed that the inclusion of CIN made the quadripartite film more hydrophobic, in which the highest value achieved was 86.6 ± 0.75° at θt=10. ATR/FT-IR spectroscopy demonstrated the formation of Schiff-base and intermolecular hydrogen bonds between components' functional groups, which enhanced the quadripartite films' thermal stability and mechanical properties. X-ray diffraction analysis suggested compatibility among the components, and changes of the surface of the films were confirmed by SEM and AFM analyses. Likewise, the antimicrobial activity of the CIN-loaded films were proved against Staphylococcus aureus, Listeria monocytogenes, Salmonella enteritidis, and Escherichia coli. The quadripartite films exhibited in vitro DPPH radical scavenging activity (~35.8%) and ferric reducing power at the maximum CIN testing concentration. The findings of this study proved that CIN-doped films could be used as promising inner functional packaging for food products.