UV Exposure Effects on Starch Films from <em>Solanum tuberosum </em>(Ecuadorian Potato): A Macro- and Nanoscale Investigation

The growing pollution caused by plastics with slow degradation kinetics is demanding the search for biodegradable alternatives. Starch-based films are a promising option, but their practical application may be limited by their potential susceptibility to rapid ultraviolet (UV) exposure degradation. This study evaluates the effect of prolonged UV-C irradiation (254 nm, 168 h) on plasticizer-free films derived from the starch of the Ecuadorian potato Solanum tuberosum (Chola variety). Films formulated at 3 % and 5 % (w/v) starch were characterized before and after UV exposure. The analysis includes the evaluation of optical, mechanical, and physicochemical properties, along with Fourier Transform Infrared spectroscopy (FTIR) and atomic force microscopy (AFM) for nanoscale surface inspection. UV irradiation increased the opacity of the films but reduced slightly their tensile strength, elongation at break, moisture content, and total soluble matter. In contrast, the elastic modulus remained relatively high. FTIR analysis revealed no significant formation of new functional groups, suggesting that UV exposure induces a physical reorganization rather than chemical degradation. AFM measurements indicated that irradiation caused only minor nanoscale alterations in the same film regions. These alterations were more pronounced in films with higher starch concentrations. The results demonstrate that UV-C exposure induces minor structural adjustments in plasticizer-free starch films derived from the Chola variety, without compromising their fundamental integrity. Consequently, this work advances the understanding of the environmental stability of these films and supports their potential application as sustainable materials, even in conditions involving UV exposure.