Effect of food simulator on barrier properties of polyvinyl alcohol packaging film

This study aims to investigate the impact of food components on the performance of polyvinyl alcohol (PVA)coated composite films. Food simulants, including deionized water representing aqueous food, 3% acetic acid representing acidic food, and 50% ethanol representing alcoholic food, were used for pouching and packaging of the PVA-coated composite films. The films were also subjected to water bath (80 degrees C for 30 min) and accelerated treatment (80 degrees C for 60 min and 100 degrees C for 60 min) to simulate industrial pasteurization and more severe damage. The morphology, chemical composition, thermal stability, barrier properties, and other characteristics of the materials were evaluated. In this study, it was found that all three simulants had an effect on the barrier properties of the films. Among them, acidic and alcoholic simulants had a relatively large impact on the oxygen barrier properties of the films, with decreases of 44.99% and 79.48%, respectively. The alcoholic simulant also had the largest effect on the moisture barrier properties of the films, with a decrease of 28.33%. Additionally, the addition of the three food simulants led to a significant reduction in the mechanical properties of the films and a significant decrease in transmittance. Microstructural characterization revealed that the above performance changes originated from the harsh conditions when the food simulants first contacted the base film, damaging the internal structure. Subsequently, the barrier layer PVA was penetrated and dissolved, thus affecting the performance. The fragmentation of thin film crystals and the penetration of the simulant were also evidenced by XRD and FTIR. These findings emphasize the influence of food itself on widely used PVA and provide guidance for the design of future PVA high-barrier packaging films.