Long-term stability and properties of potato starch films plasticized with sugar-glycerol mixtures

Herein, we evaluate the influence of polyol-glycerol mixtures (glycerol/erythritol, glycerol/xylitol, and glycerol/fructose) on the functional properties and storage stability of potato starch-based films. The basic properties of films were assessed, i.e., color, water vapor transition rate, surface properties (surface free energy, morphology), and mechanical. Some of the tested properties were re-evaluated after long-term storage (five years) in the absence of light to assess the stability of developed films. The initial mechanical properties showed tensile strength values ranging from 2.23 ± 0.31 MPa to 9.26 ± 1.38 MPa and elongation at break between 32 ± 6 and 80 ± 10 %, depending on the plasticizer type. Surface free energy varied from 51.0 ± 0.9 to 78.3 ± 0.3 mJ · m^-2, with water contact angle values of 4.4 ± 0.1 to 63.0° ± 2.0. After long-term storage, films retained approximately 88 % of their initial tensile strength and 65 % of their elongation at break, suggesting notable structural stability. These findings demonstrate the potential of sugar-polyol plasticized starch films for long-term packaging applications.