Physicochemical properties of yam starches from fifty-five lines of Dioscorea species

Abstract

This study investigated the morphology of the granules, physicochemical and pasting properties of fifty-five starches of Dioscorea rotundata and Dioscorea alata varieties. The granules sizes and shapes, swelling power, solubility, water absorption capacity, water binding capacity, pH, titratable acidity and pasting properties were evaluated by standard procedures. The result of the granule morphology showed that both varieties were in the range of large starch granules, however, D. rotundata varieties (32.40 – 57.01 µm by 22.38 – 35.70 µm) were significantly larger than those of D. alata varieties (18.33 - 48.91 µm by 13.38 – 33.10 µm). The granule sizes were observed to have a significant effect on the physicochemical properties, as D. rotundata species were significantly higher in swelling power (7.50 g/g) and lower in water absorption (66.20%) and water-binding capacities (57.16%). Also, D. rotundata species showed significantly higher peak viscosity (518.50 RVU), holding strength (260.95 RVU) and breakdown viscosity (257.54 RVU), all contributing to their potential industrial uses. The present characterisation of fifty-five varieties of Dioscorea species germplasm in Nigeria adds to the database on physicochemical properties of yams, providing relevant information for both food and non -food uses.