Starch-based biocomposites reinforced with cellulose nanofibers from potato peel byproducts

The valorization of potato peel byproducts, comprising approximately 14-40% of the total weight of fresh potatoes, through the extraction of cellulose nanofibers and their integration into starch-based biocomposites presents a sustainable strategy for enhancing the properties of biodegradable films for packaging applications. This study evaluated the physicochemical, barrier and mechanical properties of thermoplastic starch films incorporating cellulose nanofibers from potato peels (NCPP) at different concentrations (5%, 10%, and 15%). The addition of NCPP significantly increased the crystallinity index, with TPS-NCPP15 exhibiting the highest crystallinity (7.41%). Mechanical properties were significantly improved: Young's modulus increased from 1.31 ± 0.09 MPa in TPS to 7.54 ± 0.82 MPa in TPS-NCPP5, and further to 12.40 ± 0.09 MPa and 14.45 ± 0.07 MPa in TPS-NCPP10 and TPS-NCPP15, respectively. Tensile strength rose from 21.11 ± 3.42 MPa in TPS to 35.60 ± 3.04 MPa in TPS-NCPP5, and to 50.69 ± 0.42 MPa and 55.22 ± 0.09 MPa in TPS-NCPP10 and TPS-NCPP15. NCPP-reinforced films exhibited lower water contact angles than the control, indicating greater surface wettability. Water vapor permeability was reduced from 6.37 × 10⁻¹⁰ g·s⁻¹·m⁻¹·Pa⁻¹ in the control film to 3.55 × 10⁻¹⁰ g·s⁻¹·m⁻¹·Pa⁻¹ and 4.54 × 10⁻¹⁰ g·s⁻¹·m⁻¹·Pa⁻¹ in TPS-NCPP10 and TPS-NCPP15, respectively, indicating enhanced moisture barrier properties. The swelling capacity of the films was significantly enhanced with the addition of cellulose, with a more pronounced effect at 5% than at 10% and 15%. The films remained visually transparent, except at the highest cellulose concentration, where opacity increased. These findings highlight the potential of NCPP as a sustainable reinforcement material in biodegradable packaging.