Dual physical modification of elephant foot yam starch: Effects on physicochemical, structural, functional, and digestibility properties

This study investigates the physical modification of native elephant foot yam starch (NEFYS) using heat-moisture treatment (HMT) at 120°C with 25% moisture content for 1, 4, and 6 h; ultrasonication (US) at 20 kHz for 30 min; and a combination of both (HMT+US). These treatments significantly ( p <0.05) increased amylose content from 22.39% in NEFYS to 29.80% after 6 h of HMT. Dual modification increased resistant starch (RS) from 27.15% to 40.66%, and slowly digestible starch (SDS) from 10.82% to 18.42%. Pasting analysis showed reduced peak viscosities, with US-treated sample (1172 cP) indicating greater shear resistance, beneficial for weaning food applications. Microscopy revealed spherical granules in NEFYS, while HMT-modified granules showed fissures and surface cavities. Water activity declined with HMT, and all starches retained a C-type crystalline structure. Dual-modified starches also exhibited improved solubility. Overall, physical dual modification improved the functional, thermal, and nutritional properties of elephant foot yam starch. Among all treatments, HMT-1+US offered the best results, including the highest RS content, improved solubility, and pasting stability, highlighting its potential for food and industrial uses.