Quality Evaluation of Unripe Plantain and Water Yam Composite Flours and their Cooked Paste

Abstract

Rheological and sensory properties of unripe plantain and water yam selected cooked paste blends were investigated. Flour samples (unripe plantain and water yam flours) and the selected blends 90:10 (C), 80:20 (D) and 50:50 (E); water yam flour-WYF: (unripe plantain flour-UPF) were produced from oven dried unripe plantain (UP) and water yam (WY) chips. Commercial whole wheat flour (WWF-A) acted as a positive control. Sample B; water yam flour alone, acted as negative control. The flour samples were analyzed for proximate, selected functional, mineral and vitamin C composition using standard methods. Gelatinization temperature and viscosity measurement of the flour blend dispersions were also determined using standard methods. Values obtained for proximate composition ranged from 7.03 to 10.18 % for moisture contents while crude protein contents (11.64 – 7.65%) for samples were moderately reduced through blending of the flours. Fat contents of the blended samples varied between 0.32 and 1.45 %. Ash, fibre and carbohydrate contents moderately increased as inclusion of plantain flour increased. Sample D had the highest vitamin C content out of the variants and E had highest amount of magnesium and iron. There was no significant (p > 0.05) difference in the values for bulk density that ranged from 0.64 – 0.96g/cm³. Effect of temperature on consistency index modeled using Arrhenius-type equation indicated that all sample flour dispersions exhibited dilatants fluid behavior. Activation energies (8.30, 17.70 and 23.0 J/mole, respectively, for samples C, D and E) increased directly with inclusion of plantain flour. Acceptability of water yam cooked paste and other blends had no significant (p > 0.05) difference.

Keywords: Flour dispersion, gelatinization temperature, unripe plantain, viscosity, water yam.