Nutritional Evaluation of Bread Produced from Orange-flesh Sweet Potato Flour, Starch and Residue Flour

Abstract

The nutritional evaluation of bread from orange-fleshed sweet potato and its derivatives and composites were studied. The orange-fleshed sweet potatoes were washed, peeled, sliced, dried and milled to flour. The starch and non-starch residue were also produced from the orange-fleshed sweet potatoes. Different proportions of wheat and flour, wheat and starch and wheat and non-starch residue of orange-fleshed sweet potato with increasing levels of orange-fleshed sweet potato at 10, 20, 30 and 40% addition in wheat were prepared. Control samples were 100% wheat flour (A0), 100% orange-fleshed sweet potato flour (A1), 100% orange-fleshed sweet potato starch (B1) and 100% orange-fleshed sweet potato non-starch residue (C1). Breads from these different proportions were produced. The essential amino acids compositions were determined using standard procedures, while the most preferred bread samples were further subjected to in-vitro protein quality evaluation. The nutritional quality of the preferred breads was also determined using standard procedures. The GENSTAT Statistical Software (version 17.0) was used for data analyses. The essential amino acids of the bread samples ranges for lysine (1.01-4.28 g/100g), valine (3.33-6.69 g/100g), and leucine (5.32-8.91 g/100g) respectively. The result of the chemical scores of the breads essential amino acids have the following ranges for tryptophan (0.01-0.99 g/100g), methionine (0.01-0.43 g/100g), threonine (0.05-0.59 g/100g), isoleucine (0.0.18-1.12g/100g) and phenylalanine (0.23-0.92 g/100g) respectively. The most preferred bread samples from the sensory evaluation were used to prepare a diet and coded A2B: 90:10 Wheat flour and OFSP flour bread diet, AOB: Wheat flour bread diet (reference), A3B:80:20 Wheat flour and orange flesh sweet potato flour bread diet, B2B:90:10 Wheat flour and orange flesh sweet potato starch flour bread diet, B3B :80:20 Wheat flour and orange flesh sweet potato non-starch flour bread diet, C2B: 90:10 Wheat flour and orange flesh sweet potato non-starch residue flour bread diet C3B: 80:20 Wheat flour and orange flesh sweet potato non starch residue flour bread diet. The body weight changes of rats feeds with bread diet ranged from 67.80-193.30 g, with BD (-100.50 g) and PD (50.20 g) for TWG/L while the TFI ranged from 760.30-1028.10 g having a BD of 613.70 g and PD of 791.50 g and the NI ranged from 15.59-99.30 g for samples with the BD not detected and 16.22 g PD. The nutritional quality of the breads ranged respectively for FER (0.08-0.21), FCE (5.11-12.34), PER (1.02-2.46), NPR (-0.02-0.04) and AD (93.93-98.57%).