Abstract
The formulation of composite yoghurt at varying proportion from blends of whole milk and tiger nut with date fruit as sugar subtitute, focusing on health, nutrition and economic capability becomes imperative in a dynamic and challenging food system. This necessitated the need to study the rheological properties along with the quality properties and consumer’s acceptability of yogurt. Yoghurt samples were produced from whole milk and tiger nut milk in varying ratio of Whole milk-tiger nut (100:0, 90:10, 80:20, 70:30, 60:40 and 50:50) and Tiger nut-whole milk in reverse order, respectively. About 20g of date fruit powder was added to each formulation to replace sugar. Rheological properties, Qualities charateristics and mineral composition of these samples were evaluated along side the consumer acceptability.The rheological studies revealed that all the yoghurt blends displayed a non-Newtonian behaviour. The power law model well fitted the shear stress-shear rate relationship of all the yoghurt blends with coefficient of determination (R2) ranging between 0.99999-1. The consistency coefficient (k) and the uniformity index (n) ranged from 39.26-95.75 N/m2s and 0.9984-1.003, respectively. Significant difference (p<0.05) existed in the proximate composition and the mineral composition with range of value of 109.41-975.00 mg/100g (calcium), 35.01-760.26 mg/100g (magnesium), 53.42-81.42 mg/100g (potassium), 0.35-0.61 mg/10mg/100g (zinc) and 327.83-822.34 mg/100g (phosphorus) respectively. The senesory parameters values were significantly favourable interms of preferrence and acceptance towards 50:50. This study showed that incorporation of tiger nut milk and date fruits in whole powdered milk for yoghurt commercial production suggested favorable nutritional impact on the consumers.