BIOCHEMICAL ASSESSMENT OF VITAMIN-A ENRICHED CASSAVA/WHEAT FLOUR BREAD AS DIETARY INTERVENTION IN TYPE-2-DIABETES MELLITUS

Abstract

Type-2 diabetes is a metabolic disorder characterized by persistent elevation in hyperglycemia, as a result of insulin resistance, Dietary approach is one of the strategies towards effective management of type-2 diabetes. Proper selection of daily food intake may assist in controlling hyperglycemia in type-2 diabetic condition. Therefore, this study sought to investigate the sensory attributes, nutritional qualities, and glycemic response, antioxidant and antidiabetic properties of bread produced from vitamin-A cassava flour (CF)/ Wheat flour (WF) - in vitro and in vivo. High vitamin-A cassava flour (CF) and wheat flour (WF) were blended mixed in the ratios of 100:0 (100% CF and 0% WF), 50:50 (50% CF and 50% WF), 20:80 (20% CF and 80% WF), 10:90 (10% CF and 90% WF), and 0:100 (0% CF and 100% WF) and flavoured with cocoa powder (FL) for the production of the composite bread. Sensory evaluation of the composite bread showed that there were no significant (p>0.05) differences in aroma, taste and general acceptability among all the composite bread produced. The results also revealed that the different composite breads were rich in protein, fiber, potassium and amylose contents but low in ratios of soluble starch/sugar and amylopectin content as well as glycemic index. Free and bound phenolic extracts from the composite bread showed high antioxidant properties as typified by high 1,1-diphenyl-2-picrylhydrazyl, 2,2-azinobis (3-ethylbenzo-thiazoline-6-sulfonate and nitric acid radicals scavenging abilities, Fe2+ chelating ability, ferric reducing antioxidant power as well as inhibition of Fe2+ - induced lipid peroxidation in rat pancreas. Furthermore, the extracts inhibited key enzymes linked to type-2 diabetes (α-amylase and α-glucosidase) in-vitro. Feeding of diabetic rats with the composite bread revealed significant (P<0.05) reduction in blood glucose level in diabetic rat compared to diabetic control (DBC) rats. Moreover, reduced activities of α-amylase and α-glucosidase were observed in composite bread and acarbose-treated rat groups when compared to that of the DBC rat group. In addition, the DBC group had significantly (P < 0.05) higher lipid concentrations (except for high-density lipoprotein cholesterol) when compared to all other groups. The diabetic groups treated with composite bread blends had significantly (P < 0.05) reduced activity of liver enzymes (alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase) and showed elevated levels of antioxidant status (glutathione, ascorbic acid, superoxide dismutase and catalase). These results suggest that Vitamin-A enriched cassava could be a good substitute for wheat flour in the production of confectionaries. The composite bread blends could also be used as dietary intervention for diabetes type-2 management as the bread blends attenuated hyperglycemia, hyperlipidemia and hepatotoxicity. However, 100% CF and 0% WF had the highest blood glucose lowering effect as well as inhibitory effect of α-glucosidase activity.