Defatted Soy Flour Supplementation of Wheat Bread ameliorates Blood Chemistry and Oxidative Stress in Wistar rats

Abstract

Background: Bread is a convenience food made from wheat flour, which is derived from wheat and whose technology of which dates back to the ancient Egyptians. It is therefore of economic advantage if wheat importation to Nigeria can be reduced by substitution with other suitable materials. This led to the whole idea of composite flour, which is a mixture of wheat with other materials to form suitable flour for baking purposes.
Objectives: The study is to ascertain the effect of supplementation of bread with defatted soy flour on blood chemistry and oxidative stress in Wistar rats.
Methods: Wheat flour mixed with high quality defatted Soy flour at several ratios: 90:10, 80:20, 70:30, and 60:40. The 90:10, 80:20, 70:30, and 60:40 flour mixtures were used to prepare 10%, 20%, 30%, and 40% Soya bread, respectively. The control bread (100%) was prepared with 100% wheat flour. Bread produced with these blends compared with regular 100% wheat bread and was tested for chemical and organoleptic characteristics. Sixteen rats were randomly given codes and allocated to 2 different groups via tables with random numbers to feed on the 100% wheat blend and soy supplemented bread (90% wheat flour/10% soy flour) for 28 days. The weights and feed intake of the rats were computed on daily basis. Blood was taken for biochemical assays and liver was used for antioxidant assay, that is activities of catalase, super oxider dismutase (SOD) and reduced glutathine level.
Results: The activities of serum SOD and catalase were significantly increase (p<0.05) in rats fed the composite bread as compared to the control (wheat bread) and a significant decrease (p<0.05) in lipid peroxidation marker (malondialdehyde level) relative to control group. The activities of the liver enzymes (alanine amino transferase, aspartase amino transferase and alkaline phosphatase) and markers (low density lipoprotein, cholesterol and triacyl glycerol levels) showed significant decrease (p<0.05) in rats fed supplemented soy flour bread as compared to the control. There was a significant decrease (p<0.05) in the total bilirubin, creatinine and urea levels as well as total protein and albumin levels of rats as compared to control.
Conclusion: These findings establish the nutritional and health promoting benefits of soy supplemented bread.

Key Words: Defatted Soy Flour, wheat bread, blood chemistry, oxidative stress, rats