Evaluation And Optimization Of Physicochemical Properties Of Wheat Flour And Chemically Modified Starches From African Yam Beans And Cassava

ABSTRACT

Composite breads were made by supplementing wheat flour (WF) with chemically modified African yam bean starch (AYBS) and Cassava starch (CS) after the starch were produced from the cleaned seeds and roots using hammer milling system. The blends (WF/AYBS/CS 80/10/10, 80.83/10.83/8.33, 85/10/5, 82.5/10/7.5, 82.5/12.5/5, 80/13.5/6.5, 80.83/13.33/5.83, 82.50/12.5/5, 81.67/11.67/6.67, 80/12.5/7.5, 81/13.5/5.5, 83.33/10.83/5.83, 80/15/5, 84.5/10/5.5) was obtained from the D-Optimal Mixture Design of Response Surface Methodology. The Functional properties of the flour/ starch blends, Physical and Sensory evaluation of the bread was determined and subjected to Statistical Analysis of Variance (ANOVA) using models comprising the Mean, Linear mixtures, Quadratic, Special cubic and Cubic and the general acceptability determined using spider plot design of Microsoft Excel System. The models and the model terms (interactions) were judged for significance at 95% confidence intervals (p<0.05). The flour/ samples had functional properties ranging from 5.66 to 7.44 pH, 6 to 8.85%w/n Least gelation concentration, 60 to 72 ⁰C Gelation temperature, 3.86 to 4.84 % Moisture content, 0.43 to 0.52 g/cm³ Bulk density, 61 to 74.42 ml/g Water absorption capacity, 66 to 77.5 ml/g Oil absorption capacity, 2 to 5.75 % Swelling power, 1.15 to 8.1 % Swelling volume, 28.51 to 62.5 % Solubility and 15.55 to 26.25 cp Viscosity. The physical properties of the bread samples range from 0.7 to 3.2 cm Oven spring, 3.5 to 6.4 cm Height, 266.7 to 442.05 g Weight, 254.71 to 764.14 cm³ Loaf volume, 0.74 to 2.34 cm³/g Specific volume and 0.43 to 1.36 g/cm³ Bulk density. The sensory evaluation results showed that all the bread samples had high rating for all the parameters evaluated except 85/10/5% of AYBS and CS supplementation. The 84.5/10/5.5% and 80/12.50/7.5% of AYBS and CS supplementation compared better than other substitution levels which were generally acceptable as they were neither liked nor disliked by the judges. The result for the optimization of all the attributes evaluated for adequate models and model terms suggested that the blend 82.00/10.88/7.13 of AYBS and CS supplementation will satisfy all the desirable goals for optimization with the desirability value of 0.68.