Genetic variation in physical properties of flour from selected Asian yams (Dioscorea spp.)

Flours from a total of 15 genotypes of Dioscorea alata, D. esculenta, D. hispida, D. pentaphylla, and D. rotundata were evaluated to identify variation in starch-related functional properties affecting their quality for use in food processing. Significant differences were obtained among and within species for these properties. Very low amylose flours (3.8-7.4%) such as D. esculenta showed high swelling volume (SV), lower gelatinization temperatures (GT), low paste viscosities and high breakdown, and soft, sticky, and cohesive gel textures. Dioscorea rotundata flours gave slightly higher apparent amylose contents (AAC) and GT compared to D. esculenta, but moderately high and variable paste viscosities and firm, non-sticky gel textures. Dioscorea hispida flour had low AAC and GT but extremely high paste viscosity and low paste stability. Flours from wild and cultivated genotypes of D. pentaphylla and D. alata showed a range of properties with potential for use in noodle-making and for industrial uses requiring high viscosity. Genotypes BSUP 115 and BSUP 126 (D. pentaphylla) showed strong resistance to mechanical disintegration (shear-thinning). In D. alata, LA 077 purple flour gave the highest paste viscosity values and setback ratios, followed by the processing type BSUA 093, BSUA 102, and wild staple substitute BSUA 101; the Puerto Rican IA 227 and Chinese IA 401 flours gave extremely low paste viscosities, and somewhat firm, non-sticky gel textures.