Physical and structural properties of films based on whey protein concentrate/omega-3 rich oil/TiO2 as affected by nanoreinforcement geometry

Films made from biopolymers have gained significant attention recently due to their environmental benefits. Among animal proteins, whey protein concentrate (WPC) stands out as a promising alternative because it is a byproduct of the cheese industry. In this study, films were prepared using emulsions stabilized by WPC, which contained a concentrate of fish oil enriched with omega-3 fatty acids. These films were created by casting as a biobased alternative to petroleum-based plastics. All films contained 7.5% WPC, 6% glycerol, and 2% fish oil by weight. Some formulations also included Tween 20 at concentrations of 0.05% or 0.1%, and/or were reinforced with TiO₂ in two forms—either spheres or nanotubes (NTs)—at concentrations of 0.1% or 0.2% by weight to improve their physical properties. Compared to the control, the addition of nanotubes at 0.1% and 0.2% enhanced the tensile and mechanical properties. The film with 0.2% nanotubes showed the highest storage (E’) and loss (E’’) moduli, as well as the shortest elongation at break (εb) among all the films. The improved physical properties of the films reinforced with nanotubes were due to their distribution within the film matrix, which depended on the geometry.