Rheological and Pasting Properties of Flour, Extruded Products and Fresh Samples from Yellow Root Cassava, Orange Fleshed Sweet Potato, Plantain Fortified with Moringa oleifera Leaves

Introduction: There is complete dependence on wheat flour for baked products, which are imported from other parts as wheat can’t grow in Nigeria. Therefore, to reduce the cost of importation, composite flour can be an alternative. Composite flour has some advantages for developing countries such as Nigeria as it reduces the importation of wheat flour and encourages the use of locally available resource for making flour.

Methodology: Orange -fleshed sweet potatoes (OFSP), yellow roots cassava (YRC) were all sourced from National Root Crops Research Institute Umudike (NRCRI), while the plantain and Moringa oleifera leaves were gotten from Umuahia market and Michael Okpara University of Agriculture Umudike (MOUAU) respectively. The samples were processed into flour to form different blend ratio. The flour blend constitutes of yellow root cassava, orange fleshed sweet potato and plantain which were fortified with Moringa oleifera leaves at constant portion of 5% while the YRC, OFSP and plantain were varied at different concentrations.

Three (3) experiments were conducted, of which experiment 1 is the flour made from the blend of YRC, OFSP, plantain and moringa oleifera leave. Sample A, B, C, D, E F, G and H were the composite flour. A consist of 65% YRC, 10% OFSP, 20% Plantain, 5% moringa leaves powder: B consist of 70% YRC, 10% OFSP, 15% Plantain, 5% moringa leaves powder: C is 75% YRC, 10% OFSP, 10% Plantain, 5% moringa leaves powder, D is made up of 80% YRC, 5% OFSP, 10% Plantain, 5% moringa leaves powder, E is 85% YRC, 5% OFSP, 5% Plantain, 5% moringa leaves powder, F is 95% and 5% moringa leaves powder, G is 95% plantain and 5% moringa leaves powder and H is 95% and 5% moringa leaves powder respectively. Experiment 2 was the extruded baked snacks from the blend ratio of composite flour and Experiment 3 was the fresh of yellow root cassava, plantain and orange fleshed sweet potatoes analysed on fresh basis.

Results: The breakdown of the extruded baked snacks ranged between (254.72 RVU to 298.54 RVU) from sample P to J. No significant difference (P >0.05) was observed among samples K (271.64 RVU), N (276.64 RVU) and M (279.11 RVU). Peak viscosity values obtained from experiment 1 ranged from 202.31 RVU to 388.68 RVU. There was no significant difference (P >0.05) among the samples A (382.65 RVU), D (382.07 RVU), E (383.07 RVU) and H (384.63 RVU).The holding strength of the composite flour in this study range from 123.16 RVU to 256.62 RVU. The result on experiment 3i. e. fresh of yellow root cassava had the highest peak viscosity of (355.72 RVU), followed by sample R (291.75) and sample S (260.09 RVU) which were the fresh plantain and fresh orange-fleshed sweet potato. Result of trough, indicated that sample Q (117.17 RVU) had the highest trough followed by sample R (83.40 RVU) and S (80.16 RVU). A significant difference was observed on final viscosity within the fresh samples whereby sample Q (394.09 RVU) had the highest score followed by sample R (334.13 RVU) and S (300.63 RVU).

Conclusion: There was no significant difference (P >0.05) within experiment 1, 2 and 3 on peak value, final viscosity, setback, breakdown and peak time while the trough was high in experiment 1 (composite flour) than in experiment 2 and 3. As food, the extrudates with low relative viscosity can easily be eaten by infants while those with high viscosity can only be eaten easily by adults because they tend to be hard and cohesive in texture than samples with low viscosities.