Antioxidant, Anti-diabetic and Sensory Properties of Bread Produced from Flour Blends of Wheat and Pretreated African Yam Bean and Bambara Groundnut Seed Coat

Abstract

Producing bakery products with low glycemic index is expedient to replacing the consumption of foods, such as white bread, correlated with cardiovascular diseases. This research looked at the chemical, antioxidant, anti-diabetic, and sensory properties of bread made from a mix of wheat flour (WF), pretreated African yam bean (AYB) and Bambara groundnut (BGN) seed coat. Bread samples were produced from formulated composite flour (wheat flour, pretreated African yam bean and Bambara groundnut seed coats) obtained from mixture design in response surface methodology in the ratio of WF: AYB (78.2 g: 21.8 g) and WF: BGN (74.42 g: 25.57 g). Samples were evaluated for proximate, total phenol and antioxidant activity (DPPH and ABTS), dietary fibre (Soluble, Insoluble and Total), anti-diabetic (glycemic index, alpha-amylase and alpha glucosidase inhibition) and sensory properties. Data generated were subjected to Analysis of Variance to determine level of significant difference while means were separated by Duncan multiple range at p<0.05. The proximate composition of the bread samples, were moisture (30.29–33.75%), crude fibre (0.58–2.68%), protein (7.98–11.59%), ash (1.69–2.35%,) fat (1.23–2.65%), and carbohydrate (48.20–55.77%). Total phenol, DPPH and ABTS ranged between 0.87 and 3.48 mgGAE/g, 3.07–18.88% and 0.001 - 0.004 Mmol/g respectively. The insoluble, soluble and total dietary fibre were (2.91-9.28%), (1.34-4.47%) and (4.25-12.73%) respectively. The values for the glycemic index alpha-amylase inhibition and alpha-glucosidase inhibition of the bread samples were (21.85–53.54), (26.99–93.31%), and (34.21–74.44%) respectively. The sensory attributes of the composite bread were between liked slightly and liked moderately but the overall acceptability was not significantly different from the control sample made with 100% wheat flour. The study indicated that pretreated underutilized seed coats could be a useful ingredient in producing functional bread with appreciable nutrient profile.