In this study, organic acids were used as cross-linker with polyvinyl alcohol (PVA) films prepared by a solution-casting method for food packing applications. The effect of incorporating three different organic acids, i.e., malic acid (MA), tartaric acid (TA), and lactic acid (LA), on the physicochemical and biological properties of PVA was explored in detail. The crystalline phase, optical absorption, and functional groups were examined via UV-Vis and Fourier transform infrared spectroscopy. Thermal, microstructural, and surface investigations were conducted by thermogravimetric analysis and scanning electron microscopy, and the antibacterial activity was evaluated. The surface topography and roughness were found to have a strong effect on the bactericidal properties of the films, as confirmed by atomic force microscopy. Among the considered films, PVA/LA exhibited the highest bacterial inhibition, which was largely due to its capacity to modify the local pH and alter the permeability of the microbial layer by disrupting bacteria-substrate interaction. In general, the composite film was found to have attractive properties and can be considered as a food packaging material with low environmental impact based on polyvinyl alcohol.

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The present study demonstrates the role of multicarboxylic acids as crosslinkers to polyvinyl alcohol (PVA) films were fabricated by solution casting method for food packing applications. Effect of incorporating different carboxylic acids namely oxalic acid (OA), succinic acid (SA) and citric acid (CA) on physicochemical and bioactive properties of PVA were investigated in detail. The crystalline phase, optical absorptions and the functional group were analyzed through X-Ray diffraction (XRD), UV-Vis and Fourier Transform Infrared (FTIR) Spectroscopy. Thermal, microstructure and surface analysis were studied by Differential thermal analysis (TG/DTA) and Scanning Electron Microscope (SEM) analysis and the chief antibacterial activity. The rheological study was carried out using precursor polymer solutions with different crosslinkers reveal that viscosity of PVA/CA solution is higher. Surface topography and roughness exert a strong influence on bactericidal properties of films as evidenced by Atomic Force Microscope (AFM) analysis. Among they studied films, PVA/CA exhibits higher bacterial inhibition efficiency mainly due to the ability of CA to alter local pH and cause an alteration in the permeability of microbial membrane by disrupting bacterial substrate transport. In addition to this food quality analysis results of microbial tests revealed an increase in the microbial shelf life of sliced carrot from 1 to 5 days for PVA/CA film compared to the control and commercial.

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