Combining proteolytic enzyme with non-thermal ultrasound and microwave methods for enhanced extractability and modified functionality of dry bean (Phaseolus vulgaris) starch: A chemical-free strategy

This study investigated the extraction of dry bean starch using a food-grade protease enzyme and its integration with ultrasound and microwave treatments, to compare their effects on starch recovery and functional properties. Enzymatic treatment at 0.5 % protease concentration yielded a starch recovery comparable to the conventional alkaline method (∼ 84 %). Integration with ultrasound and microwave allowed higher recovery (∼ 87 %) at lower enzyme concentrations of 0.1 % and 0.25 %, respectively. Ultrasound treatment significantly modified starch characteristics, including surface damage, amylose content, thermal stability, retrogradation behavior, swelling power, solubility, pasting viscosities, rheological properties, and crystallinity. In contrast, microwave treatment induced limited changes, mainly enhancing gel strength and pasting properties while reducing crystallinity. In vitro digestibility revealed monophasic behavior, with ultrasound-treated starch exhibiting increased digestibility and a higher expected glycemic index (eGI). Thus, protease-assisted extraction offers a sustainable alternative to alkaline methods, while its integration with ultrasound or microwave reduces enzyme requirements, enhances starch recovery, and alters starch functionality, yielding application-specific starch without additional modification.