Nutritional, physico-chemical and sensory properties of yam flour dough fortified with Moringa oleifera seed flour

Abstract

Yam (Dioscorea spp) is the second most important root/tuber crop in Africa after cassava and is an important source of carbohydrate. Low protein content of yam flour has been a major concern in its utilization, hence the objective of this research was to investigate the effect of addition of Moringa oleifera seed flour on the nutritional, physico-chemical as well as sensory qualities of yam flour dough. Moringa seed flours obtained through fermentation, germination and regular milling of unprocessed seed were added to yam flour at three inclusion levels (10, 20 and 30 %) and were subjected to analyses. Chemical composition, Pasting properties and sensory evaluation of the products were determined using AOAC methods, Rapid visco analyser and nine point hedonic scale, respectively. Moisture, fat and crude fibre contents of the samples ranged from 10.97 to 12.27%, 2.04 to 2.96% and 1.71 to 2.08%, respectively. Calcium, Iron, Sodium, Potassium and Phosphorus were significantly (p<0.05) affected by the Moringa flour inclusion, however, copper was not affected. Phosphorus and copper contents (mg/100g) ranged from 90.43 to 156.38 and 0.04 to 0.08, respectively.There were significant differences (p<0.05) in water and oil absorption capacity, swelling power and solubility index whereas no significant difference (p>0.05) exist in the bulk density of the samples. The highest value of 96.54% was recorded for unfortified yam flour for water absorption capacity while yam flour fortified with 10% fermented moringa seed flour has the lowest value of 89.58%.The swelling power ranged from 10.85 -11.77 while Bulk density is from 0.73-1.81g/ml . Germinated Moringa substituted flour showed highest pasting properties (peak, trough, final and setback viscosities) followed by fermented Moringa substituted flour. Aside trough viscosity, the pasting properties increased significantly (p<0.05) with increased Moringa flour inclusion level. Higher (8.17) and lower (5.42) ratings were observed for colour of dough prepared from yam flour fortified with 20% germinated Moringa seed flour and 20% raw Moringa seed flour, respectively.