Incorporation of neem oil emulsions produced by high-pressure homogenization into sodium alginate films

The incorporation of bioactive compounds into biopolymer films via high-pressure homogenized emulsions represents a promising strategy for developing functional materials. This study investigated sodium alginate (SA) films containing 0.5%, 1.0%, 2.0%, and 3.0% of neem oil nanoemulsion (NOE) stabilized with pea protein. Morphological analysis revealed increased heterogeneity with higher NOE levels, characterized by lipid domain formation and surface irregularities detected by AFM. FTIR analysis confirmed interactions between SA and NOE, while XRD showed no induced crystallinity. TGA/DTG tests indicated that the emulsion did not affect the thermal degradation profile of SA. The addition of NOE increased film thickness, but low concentrations did not significantly affect tensile strength. Higher NOE concentrations reduced tensile strength and elastic modulus, while elongation at break remained stable. Water vapor permeability and moisture content showed no significant changes, indicating maintenance of the hydrophilic character of SA. In contrast, color and opacity measurements showed that the films became yellower and less transparent. The presence of NOE also provided UV-blocking capacity, antioxidant activity against DPPH and ABTS radicals, and antifungal activity against Alternaria alternata and Penicillium expansum . Overall, the results demonstrate that the developed films exhibit promising functional properties within the scope of a preliminary experimental study and may be considered potential candidates for future studies on active packaging applications.