Whey Protein Concentrate (WPC)/Fish Oil Concentrate Nanoemulsion-Based Nanocomposite Films Reinforced with Nano TiO2 in Two Morphologies

Abstract

Nonbiodegradable, petroleum-based food packaging materials have been shown to cause significant environmental harm, particularly to aquatic ecosystems. As a sustainable alternative, nanocomposite films were developed from nanoemulsions stabilized by whey protein concentrate (WPC), incorporating a discontinuous phase rich in omega-3 oils and reinforced with titanium dioxide (TiO2) nanoparticles in two distinct morphologies: spheres and nanotubes. The effects of droplet size in the discontinuous phase and nanoreinforcement geometry on the films’ physical and mechanical properties were investigated. Film structure and nanoparticle distribution were characterized using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and small- and wide-angle X-ray scattering (SAXS/WAXS). WPC demonstrated environmental adaptability in these nanostructured systems, producing films with uniform thickness, water vapor permeability (WVP), water content, and solubility across different formulations. The use of nanoemulsions as the initial system improved film transparency compared to the ones reported in literature for conventional emulsion-based films. Incorporation of TiO2, whether spherical or tubular, significantly enhanced the films’ light-blocking capabilities. Films reinforced with nanotubes exhibited superior mechanical and tensile performance, achieving the highest storage modulus (E′) and Young’s modulus (E) values among all samples. Nanotube reinforcement also led to reduced opacity and proved more effective than spherical nanoparticles in strengthening the matrix. SEM and EDS analyses revealed a more homogeneous distribution of nanotubes throughout the polymer matrix, in contrast to the bottom-surface accumulation observed with spherical particles. This difference in spatial distribution contributed to the enhanced structural integrity and overall performance of the nanotube-reinforced films. The film containing 0.2% TiO2 nanotubes had the best physical properties, highlighting its strong potential as a sustainable alternative to conventional petroleum-based plastics.