Modification of bitter yam (Dioscorea dumetorum) starch by octenyl succinic anhydride and microwave irradiation treatment: Preparation, morphology, structure, and functionality

Abstract

Starch was extracted from bitter yam (Dioscorea dumetorum) and subsequently modified through esterification (succinylation) and  microwave treatment. The functional properties of the starches were then examined. Proximate composition analysis showed that, after  modification, the succinylated (OSABS) and microwavetreated (MTBS) starches exhibited lower moisture content but higher levels of  protein, ash, crude fiber, and fat compared to the untreated bitter yam starch (UBS). Both modifications substantially improved the  swelling power and solubility profile of OSABS and MTBS at 80 °C. SEM micrographs revealed no surface damage for the OSABS sample,  but showed major granule damage for the MTBS, with the granules appearing shriveled and collapsed. The starches were further  characterized using FTIR, TGA, XRD, and light spectroscopy. Gelation studies indicated that the UBS sample is a superior gelling agent  compared to the modified derivatives. All forms of modification raised the pasting temperature but reduced the peak, trough,  breakdown, setback, and final viscosities. Additionally, the modified starches demonstrated excellent paste clarity and pasting properties, making them suitable for specific applications in the industries. Overall, modifying bitter yam starch resulted in changes to its properties,  thus, using octenyl succinic anhydride and microwave treatment may be a superior alternative to conventional modification methods.