Preparation and Characterization of Lactobacilli-Loaded Composite Films with Sustaining Antipathogenic Activity and Preservation Effect

Bioactive composite films were obtained by adding Lactobacillus paracasei into a hydroxypropyl cellulose (HPC)-konjac flour (KF) matrix through a casting method. The mechanical, optical, and barrier properties were tested to determine the influence of the addition of lactobacilli into complex films. For purpose of evaluating the surface morphology of the composite films, scanning electron microscopy and atomic force microscopy were carried out. Fourier transform infrared spectroscopy and X-ray diffraction analyses were conducted to evaluate intermolecular interactions and crystallinity, respectively. Moreover, the microbial viability of the lactobacilli and the antibacterial activities of the bioactive films against pathogenic organisms were measured. The results indicated that the mechanical properties, crystalline properties, oxygen permeability, and color characteristics were not notably altered; nevertheless, the gloss and water vapor barrier properties were relatively weakened by the incorporation of L. paracase. The HPC-KF-L. paracasei films were effective in inhibiting both gram-positive (Listeria monocytogenes, Staphylococcus aureus) and gram-negative (Escherichia coli, Salmonella typhimurium) pathogens, and the films can retain physical property and antibacterial activity within a storage period of 30 days. The composite films, acting as suitable carriers for L. paracasei and possessing noteworthy bacteriostatic activities, could be developed as bioactive packaging for preserving food. Practical ApplicationFor the sake of the high desires of consumers for food safety and quality, the development of innovative bioactive packaging has attracted wide attention. In this work, the prepared films containing lactic acid bacteria showed great physical property, antipathogenic activity, and fresh-keeping property preservation, and have great application potential in fresh food preservation.