Electrospun Poly(vinylpyrrolidone)/Thymus vulgaris L. Mats for the Protection of Fresh Berries Against Spoilage

The use of non-biodegradable plastic food packaging materials has become a major environmental concern. These plastics release chemicals and microplastics during degradation, harming wildlife and entering the food chain, posing risks to both environmental and human health. This study aimed to evaluate electrospun poly(vinylpyrrolidone) (PVP) mats incorporating natural antibacterial Thymus vulgaris L. extract (TE) and natural crosslinker citric acid (CA) as alternative food packaging materials. Packaging mats with TE and/or CA combinations in PVP were evaluated for their structural, chemical, optical, and shelf-life-enhancing effects on blueberries. The results show that dissolving PVP in TE extract and adding CA in PVP ethanol-water or TE-based solutions significantly affected the viscosity and conductivity of the electrospinning solutions, thereby influencing the morphology of electrospun mats. FTIR analysis confirmed the incorporation of TE into the polymer and indicated CA induced hydrogen bonding, interactions that may reduce the polymer chain mobility and increase the brittleness of the electrospun mat. In tests with blueberries, it was estimated that the commonly used traditional food film minimized blueberry weight loss, whereas the porous electrospun PVP and PVP/TE mats allowed greater moisture release and preserved better visual quality by reducing wrinkling and dehydration. Overall, electrospun PVP-based mats functionalized with TE show promise as sustainable food packaging materials that balance moisture management with product appearance.