Elephant foot yam starch (EFYS) granules were subjected to heat-moisture treatment (HMT) at 110 °C for 3 h with different moisture levels ranging from 15% to 35%. The effects of HMT on the morphology, crystalline structure, and pasting properties of the EFYS granules as well as the thermal and functional properties of HMT-modified starch (HMTS) granules were examined. Scanning electron microscopy showed that the EFYS granules were spherical, but the HMTS granules exhibited granular aggregation and fissures and cavities on the granule surfaces. After HMT, significant (p < 0.05) differences were observed in the color, crystallinity, and water activity between the EFYS and HMTS granules. Both the type of granules exhibited C-type crystalline structure. The solubility and pasting temperature was significantly higher (p < 0.05) but swelling power was significantly lower in the HMTS than in the EFYS granules. The HMTS granules exhibited higher gelatinization temperatures and lower gelatinization enthalpy than the EFYS granules. The results showed that HMT significantly changed the physicochemical and functional properties of EFYS; thus, HMT can considerably expand the range of EFYS applications and enable its use in manufacturing products, such as extruded foods, thickeners, and binding agents, which require processing at high temperatures.
Keywords: Elephant foot yam; Heat-moisture treatment; Morphology; Starch; Thermal properties.
Copyright © 2019 Elsevier B.V. All rights reserved.