Citrus Essential Oil Micro- and Coarse Emulsions in PVA/Sodium Alginate Active Films: Evaluation of a Selected Film for Chilled Pork Preservation

Hydrophobic essential oils are difficult to incorporate uniformly into hydrophilic polymer matrices. This study compared a citrus essential oil (CEO) microemulsion-based formulation series (CEO-M) with a coarse-emulsion series (CEO-C) at nominal CEO concentrations of 20–100 mg mL−1 in poly(vinyl alcohol)/sodium alginate (PVA/SA) composite films. Because the two emulsion series differed in emulsifying-phase composition and preparation procedure, their effects were interpreted at the formulation level. Mechanical, optical, barrier, microstructural, and radical-scavenging properties were evaluated, and PVA-SA-60M was selected for further evaluation based on its overall property profile. After standardized 100-fold dilution with distilled water, CEO-60M exhibited a smaller hydrodynamic diameter, lower polydispersity index, and more negative ζ-potential than CEO-60C at a nominal CEO concentration of 60 mg mL−1. Targeted GC-FID analysis gave estimated limonene retentions of 57.0 ± 4.6% and 41.0 ± 3.4% in PVA-SA-60M and PVA-SA-60C, respectively. In a release-based film-disk assay, both CEO-containing films produced growth-inhibition zones against Penicillium expansum and Botrytis cinerea. During 8 days of storage at 4 °C, pork wrapped with PVA-SA-60M showed lower TBARS than both the unwrapped and neat PVA-SA film control treatments and lower TVC and TVB-N than the unwrapped control at later storage stages. Color measurements did not show an additional endpoint advantage over the neat PVA-SA film. These results support further evaluation of PVA-SA-60M as an active film formulation for chilled pork.