Dry heating treatment (DHT) is an environmentally friendly technique of starch modification, inducing carbonyl group formation and altering the molecular size distribution of starch. These modified molecules interact differently between each other, with water and glycerol, potentially forming a new polymeric matrix. In this study, potato starch-based films were produced by the casting technique using native and DHT-modified starch treated for 1, 2, and 4 h at 130 °C. Glycerol was used as a plasticizer, and water as the solvent. The films were characterized in terms of morphology, crystallinity, mechanical properties (tensile properties, puncture resistance, and resistance to tear propagation), water vapor permeability, moisture content, solubility in water, and light transmission (UV, visible, and IR wavelengths). The results revealed that DHT-induced molecular rearrangements, affecting the material’s performance in non-monotonic behavior. Starches processed for 1 and 2 h resulted in films with superior mechanical properties, exhibiting increases in Tensile Strength (up to 73%) and Young’s modulus (up to 374%) compared to the native starch film. These films also showed reduced light transmission. Conversely, prolonged treatment (4 h) decreased Tensile Strength and Young’s modulus, and increased light transmission. Furthermore, DHT films exhibited up to 41% reduction in water vapor permeability, as well as decreased moisture content, water solubility, and thickness, while displaying increased crystallinity. These findings highlight DHT as a simple and promising approach for enhancing the performance of potato starch-based films, allowing for diversified properties depending on processing conditions and expanding their potential applications, for example in packaging applications.
Gomes et al. (Sun,) studied this question.