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. hi spida, D. pentaphylla, and D. rotundata were evaluated to identify variatio n in starch-related functional properties affecting their quality for use i n food processing. Significant differences were obtained among and within s pecies for these properties. Very low amylose flours (3.8-7.4%) such as D. esculenta showed high swelling volume (SV), lower gelatinization temperatur es (GT), low paste viscosities and high breakdown, and soft, sticky, and co hesive gel textures. Dioscorea rotundata flours gave slightly higher appare nt amylose contents (AAC) and GT compared to D. esculenta, but moderately h igh and variable paste viscosities and firm, non-sticky gel textures. Diosc orea hispida flour had low AAC and GT but extremely high paste viscosity an d low paste stability. Flours from wild and cultivated genotypes of D. pent aphylla 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 mechanic al disintegration (shear-thinning). In D. alata, LA 077 purple flour gave t he highest paste viscosity values and setback ratios, followed by the proce ssing type BSUA 093, BSUA 102, and wild staple substitute BSUA 101; the Pue rto Rican IA 227 ar;and Chinese IA 401 flours gave extremely low paste visc osities, and somewhat firm, non-sticky gel textures.