Influence of physicochemical properties of yam starch and flour on extensibility of pounded yam in Côte d'Ivoire

Abstract

In this study, we determined pounded yam (PY) extensibility of 19 yam genotypes from Cote d’Ivoire by two procedures: uniaxial extensibility (UAE) and bi-extensional viscosity (BEV); while the physicochemical properties of yam flour and starch such as the swelling power, solubility, pasting properties, amylose and pectin were analysed. We hypothesized that the extensibility of PY significantly depended on inherent physicochemical properties of the yam. Results showed that extensibility of PY ranged between 3.8 and 20 mm and BEV ranged between 2.7·10⁴ - 15.7·10⁴ Pa s, and were significantly different among the yam genotypes (P < 0.0001). Solubility of yam flour and starch ranged between 11.2 - 24.5 % and 7.5–13.9 %, respectively. The peak viscosity of yam flour ranged between 1895 and 3036 cP, varying significantly with genotype and specie. Correlations and multilinear regressions revealed PY extensibility was significantly estimated by solubility and peak viscosity of yam flour (P = 0.005, R² = 0.83). The results are important for breeders in screening and selecting phenotypic traits to breed improved yam varieties with excellent PY quality.