NUTRITIONAL, PHYSICO-CHEMICAL AND SENSORY PROPERTIES OF BAMBARA GROUNDNUT (Vigna subterranean L) ENRICHED BIO-FORTIFIED GARI

Abstract

The nutritional, physico-chemical and sensory properties of biofortified gari enriched with bambara groundnut flour at different supplementation levels were studied. Bambara groundnut seeds were sorted, roasted at 140 0C for 45 minutes, cooled, milled and sieved using 0.5 mm mesh size to produce bambara groundnut flour. Bambara groundnut was toasted with the fermented cassava mash in proportion 100% as control and (10:90), (15:85), (20:80) and (25:75) respectively. The toasted samples were cooled and subjected to physico-chemical analyses and sensory evaluation. The protein, fat, fibre, ash, energy, pH increased with level of enrichment. The protein increased from 3.13% in the control sample to a range of 12.61 to 21.84% in the enriched samples. The fat increased from 2.89% in the control to a range of 8.78 to 12.55% in the enriched samples while ash content in the control sample was 2.52% and increased from 4.01 to 5.92% in the enriched samples. Also the fibre increased from 2.39% in the control to a range of 3.29 to 4.90% in the enriched samples and a positive trend was observed in the energy value for the control 347.81 kcal which increased between 375.78 and 396.47 kcal in the enriched samples. The carbohydrate content reduced from 77.32% in the control sample to a range of 49.04 to 61.58% in the enriched samples as supplementation increased while the moisture content decreased from 11.75% in control to 5.75-9.73% in enriched samples. The cyanide content was reduced from 6.94 mg/kg in the control to 5.46- 6.70 mg/kg in the enriched samples while the saponin content increased from 1.72 mg/g in control to between 1.75 and 3.39 mg/g in the enriched samples. The phytate content increased from 5.76 mg/g in the control sample to a range of 5.78 -7.44 mg/g in the fortified samples as level of fortification increased. Similar trend was observed in trypsin inhibitor content which increased from 11.06 mg/g in control sample to 14.93-31.45 mg/g in the enriched samples. Bulk density in the control sample was 0.50 g/ml and increased to a range of 0.53-0.56 g/ml in the enriched samples. The swelling index, water absorption capacity and reconstitution index decreased as supplementation level increased. The swelling index ranged from 205% (control sample) to 112.5-202.5% (enriched samples), water absorption capacity from 550% (control sample) to 405-485% (enriched samples) and reconstitution index 4.83% (control sample) to 3.55-4.67% (enriched samples) respectively. The ferric reducing antioxidant potential (FRAP) was 0.60 mg AAE/g for the control sample and increased between 0.98 and 6.29 mg AAE/g in the enriched samples as the level of fortification increased. Similar trend was observed for the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay with the control sample having the free radical scavenging ability at 5.1% and increased between 7.0% and 16.3% for the enriched samples. Amino acids content increased individually between the control and enriched samples as supplementation increased with glutamic acid as the highest of the amino acids with control (10.30 g/100 g protein) and increased to a range of (10.75-12.41 g/100 g protein) for the enriched samples. Sensory evaluation revealed that the enriched samples are more nourishing due to improved protein and fats contents that can reduce cases of PEM in growing children and pregnant women. The sample BFGB1 with 10% fortification level was the best amongst the fortified samples. The conversance of the panelists with unfortified gari samples cannot be over-emphasized in the control sample.