Enhanced mechanical and water resistance properties of gelatin-based antimicrobial films via a double crosslinked...

Gelatin (GL), a biodegradable and biocompatible protein, holds significant potential as a sustainable alternative to synthetic polymers in food packaging. However, its inherent hydrophilicity and limited mechanical strength restrict practical applications. To address these challenges, this study developed a gelatin/glyceryl monolaurate/genipin (GL/GML/GP) composite film via a casting blend method. The dual modification strategy aimed to establish a chemically crosslinked network (via GP) and integrate hydrophobic antimicrobial agents (GML) to enhance structural integrity, barrier properties, and functionality.

Fourier-transform infrared (FTIR) and scanning electron microscopy (SEM) analyses confirmed that GP formed a stable crosslinked network, effectively encapsulating GML particles and preventing aggregation. Hydrogen bonding between hydroxyl groups of GML and the amino/amide moieties of GL further enhanced interfacial compatibility, yielding a uniform and dense matrix. The composite films exhibited exceptional mechanical strength (25.99 MPa) and fracture toughness (238.45%), representing increases of 107.26% and 176.55%, respectively, over pure GL films. Barrier properties improved significantly, with water vapor permeability reduced to 3.12 × 10^-10 g·m·m^-2·s^-1·Pa^-1 and oxygen permeability to 5.89 × 10^-14 kg·m·m^-2·s^-1·Pa^-1. Additionally, GML conferred robust antimicrobial activity against Staphylococcus aureus, highlighting its suitability for active food packaging.

The GL/GML/GP composite films synergistically combine enhanced mechanical robustness, superior barrier performance, and antimicrobial functionality, addressing critical limitations of conventional GL materials. This work not only advances the design of high-performance bio-based packaging but also provides a scalable framework for developing multifunctional biopolymer composites. © 2025 Society of Chemical Industry.