Unlocking the Potential of Three Yam Species (Dioscorea spp.) as Starch Sources: Physicochemical, Functional, Morphological, Thermal, and Rheological Characterization

Yams (Dioscorea spp.) are tubers with high agro-industrial potential due to their elevated starch content; however, their use remains mainly limited to fresh consumption. This study aimed to comparatively evaluate the physicochemical, functional, morphological, thermal, and rheological properties of native starches from three yam species, Dioscorea alata, Dioscorea rotundata, and Dioscorea cayenensis, to study their potential as sources of starch for food applications. The starches exhibited spherical and ovoid granules. Amylose content was relatively high, at 37.76%, 38.71%, and 32.58% for D. alata, D. rotundata, and D. cayenensis, respectively, exceeding the range commonly reported for yam starches. Significant differences were observed in water and oil retention capacity and swelling power, with D. cayenensis showing greater swelling at high temperatures. Pasting properties differed among species; D. rotundata exhibited the highest peak viscosity and greater paste stability, while D. alata showed the highest pasting temperature and breakdown viscosity. D. rotundata also presented the highest final viscosity, whereas setback viscosity did not differ significantly among species. Gelatinization temperatures exceeded 70 °C. All starches displayed pseudoplastic behavior and predominantly elastic properties (G′ > G″), with D. rotundata exhibiting the highest yield stress (τ0) and greater structural rigidity, as indicated by its higher G′ and G″ values. Overall, these findings highlight the potential of starches from the three yam species as value-added starch sources for food applications, based on their distinct physicochemical, functional, thermal, and rheological properties.