Microstructural, physicochemical, thermal, and rheological properties of starches from commonly consumed yam...

This study assessed the starch content of ten yam varieties commonly consumed in West Africa to clarify their structural, thermal, physicochemical, and rheological properties and to support their potential food and industrial applications.

The yam starches differed significantly in functional, thermal, and rheological properties. The different samples were given different codes. The sample coded KNE-C exhibited the highest amylose content at 42.7%. The starch granules were round and elliptical, with sizes ranging from 14.8 μm (sample SD3-G) to 24.1 μm (sample BET-C). X-ray diffraction analysis indicated peaks at 5.7°, 15°, 17°, and 23° 2θ, which correspond to a type C crystallinity pattern. The starch relative crystallinity was significantly lower (P ≤ 0.05) in sample OBI-N (32.49%) than sample KPO-C (40.76%). Gelatinization varied significantly (P ≤ 0.05) among the yam starch varieties, with a temperature range (ΔT) of 14.9 to 19.4 °C. A rapid visco analyzer (RVA) was used to show that peak time ranged between 5.0-5.5 min, pasting temperature ranged between 77.6-84 °C, and viscosity ranged between 4.114 Pa^.s and 5.820.5 Pa^.scP. The starches displayed viscoelastic properties and solid-like behavior (G' > G″). Gel hardness varied from 5.74 N in sample KPO-C to 10.74 N in sample SD4-G. Principal component analysis showed that components PC1 and PC2 together accounted for 55% of the total variance, and PC3 increased the cumulative variance to 71%.

The starches differed in microstructure, physicochemical, thermal, and rheological properties. This study provides a valuable basis for the selection of yam starch with specific properties suited for specific food applications in both food and non-food industries. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.