Bio-based sweet potato starch cryogels: Linking hydrogel rheological properties to cryogel structure-functionalities

Starch-based cryogels provide a sustainable solution to environmental and industrial challenges due to their biodegradability and tunable properties. Although sweet potato starch is abundant and low-cost, it remains underutilized, representing an economically attractive and sustainable source. This study reports the development of starch-based cryogels using sweet potato as a novel starch source. The effect of starch concentration and gelatinization degree on hydrogel rheology was correlated with cryogel structural, mechanical, and thermal properties. Higher starch concentrations produced more elastic dispersions with lower gelation temperatures and enhanced molecular interactions, which improved structural integrity during drying, resulting in stronger and less deformable cryogels. Gelatinization times of 7 and 15 min resulted in denser networks with smaller and more continuous pores. DSC analysis confirmed rapid gelatinization of sweet potato starch (86% at 90 °C/15 min). Water absorption increased (up to 9.79 g/g) with starch concentration and gelatinization time, while oil absorption was higher at lower starch levels (19 g/g). Additionally, low thermal conductivity (0.035-0.037 W/m·K) confirmed the cryogel insulation capacity. The results demonstrate that sweet potato starch-based cryogels combine enhanced functionality with sustainability, providing an alternative to conventional materials. These improvements underscore their potential applications in food, nutraceutical, and packaging areas.