From Emulsions to Films: The Role of Polysaccharide Matrices in Essential Oil Retention Within Active Packaging Films

Essential oil-loaded edible films have emerged as promising natural systems for active food packaging due to their antimicrobial and antioxidant potential. However, retaining volatile bioactives within hydrophilic matrices remains challenging. In this regard, this study compared the performance of carboxymethylcellulose (CMC), citrus peel pectin (CPP), and potato starch (PS) edible films as encapsulating systems of orange (<i>Citrus sinensis</i> L. Osbeck) essential oil using Tween 80 as surfactant and glycerol as a plasticizer. Film-forming emulsions were characterized regarding droplet size distribution and rheological behavior. Films were analyzed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Limonene retention was quantitatively determined post-drying through gas chromatography. CMC-based films exhibited the highest retention (~65%), primarily due to their higher viscosity, which limited oil droplet mobility and volatilization. Despite presenting similar internal porosity, PS films showed significantly lower retention (~53%), attributed to larger droplet size and lower viscosity. CPP films, with the smallest droplets and intermediate viscosity, showed similar limonene retention to PS-based films, highlighting that high internal porosity may compromise encapsulation efficacy. The results emphasize that matrix viscosity and emulsion stability are critical determinants of essential oil retention. Although polysaccharide films, particularly CMC, are promising carriers, further structural and processing optimizations are required to enhance their encapsulation performance for commercial applications.