The effect of cross-linker type on structural, antimicrobial and controlled release properties of fish gelatin-chitosan composite films incorporated with ε-poly-L-lysine

In this study, active antibacterial cross-linked composite films were prepared through incorporating epsilon-poly-L-lysine (epsilon-PLL) into Siberian sturgeon gelatin-chitosan mixture. Cross-linking was performed by Glutaraldehyde (G) and/or Cinnamaldehyde (C). The antimicrobial, epsilon-PLL release, mechanical and morphological properties were then investigated. The addition of G to the biopolymer mixture significantly resulted in lower water vapor permeability, enhanced mechanical strength, lower moisture content, and water solubility. The FTIR spectra indicated the formation of imine bonds in the composite film network. The microstructure of composite films was affected by the cross-linking agent. The films cross-linked by G and C showed smooth and rough surfaces, respectively. C induced very small pores in the cross-section of the composite film. The composite films incorporated with epsilon-PLL revealed higher and steady-state in vitro antimicrobial properties against food spoilage bacteria. A higher release of epsilon-PLL and hence higher antibacterial activity was measured in the matrices cross-linked by C than those cross-linked by G. The results showed that the epsilon-PLL-fortified fish gelatin/chitosan composite films can be considered as a food-packaging material. G and C, as cross-linkers, can improve the structural and antimicrobial properties of this composite film. (C) 2021 Published by Elsevier B.V.

Automated summary

In this study, active antibacterial composite films were prepared by incorporating epsilon-poly-L-lysine (epsilon-PLL) into Siberian sturgeon gelatin-chitosan mixture and cross-linking with Glutaraldehyde (G) and/or Cinnamaldehyde (C). The addition of G resulted in improved mechanical properties and lower water vapor permeability, while C led to higher release of epsilon-PLL and stronger antibacterial activity. The results suggest that epsilon-PLL-fortified fish gelatin/chitosan composite films can be used as food packaging material with enhanced structural and antimicrobial properties.