COMPOSITIONAL STUDIES, ANTIOXIDANT PROPERTIES -GLUCOSIDASE-AMYLASE AND AND INHIBITION OF ACTIVITY BY UNRIPE PLANTAIN/WHOLE WHEAT BLENDED BREAD

Abstract

Dietary approach has been suggested as possible alternative strategy in treatment and management of diabetes and its attending complications. Therefore, this study investigate and compare the nutritional qualities, antioxidant activities and inhibitory effects of breads produced from unripe plantain-wheat composite flour blends on key enzymes relevant to type-2 diabetes (α-amylase and α-glucosidase). Unripe plantain were processed into flour and used to replace wheat flour, in the percentages of 100, 75, 50, 25, 0, and thereafter fortified with powdered orange peels, for bread production. Subsequently, the sensory qualities, proximate composition, antinutrients and mineral composition were determined. Furthermore, the total phenol, total flavonoid, antioxidant properties, α-amylase and α-glucosidase inhibitory abilities of the breads produced were determined. The phenolic constituents of the breads were partially characterized using gas chromatography. There was no significant (p>0.05) difference in sensory qualities of all the breads produced. Carbohydrate content ranged from (50.93-59.22) %, Protein content ranged from (15.41-23.52) % while Fibre content ranged from (0.41-0.78)%. In addition, Tannin content ranged from (13.18-18.95)mg/g, Phytate content ranged from (0.3-0.4)mg/g and Oxalate content ranged from (0.17-2.52)mg/g. The total phenol ranged from 24.5mg/g (100% wheat flour bread WWB) to 26.2mg/g (100% unripe plantain flour bread UPWB100) while total flavonoids ranged from 0.84mg/g (100% wheat flour bread WWB) to 0.91mg/g (100% unripe plantain flour bread UPWB100). All bread extracts exhibited strong antioxidant properties; UPWB100 (61.65%) had the highest DPPH radical scavenging ability, while WWB (43.28%) had the least; UPWB100 (21.0 mmol. TEAC/100g) had the highest ABTS radical scavenging ability while WWB (12.0 mmol. TEAC/100g) had the least. In a similar manner, UPWB100 (4.11 mg AAE/g) had the highest ferric reducing antioxidant properties, while WWB (2.57 mg AAE/g) had the least. UPWB100 (96.50%) had the highest Fe2+ chelating ability while WWB (88.00%) had the least. Furthermore UPWB100 had the highest inhibitory effect on α-amylase (EC50 = 7.78mg/g) and α-glucosidase (EC50 = 5.70mg/g) while WWB [α-amylase (EC50 = 15.15mg/g) and αglucosidase (EC50 = 7.00mg/g)] has the least in vitro. GC characterization revealed the presence of some phenolic constituents. The high nutritive properties, antioxidant capacity and anti diabetes ability of the breads produced, therefore, make them cheap dietary intervention for the management of type 2 diabetes and 100% unripe plantain flour bread appeared to be the best.