Effect of the Use of Different Concentrations of ‘Kuuru’ on the Nutritional Quality of Fermented Parkia biglobosa Seeds

Abstract

The study was carried out to determine the effect of different concentrations of ‘kuuru’ on the nutritional quality of fermented African locust bean (Parkia biglobosa) seeds. The dried seeds were processed into ‘iru-pete’, either by boiling the seeds with varying concentrations (1:300 to 1:50 w/w) of ‘kuuru’ or use of starter culture (Bacillus subtilis strain BC4333). The fermentation was carried out in an incubator at 35°C for 36 h. Commercial samples of ‘iru-pete’ and ‘iru-woro’ were used as control. The unfermented sample and fermented products were analyzed for sensory properties, proximate composition, concentration of anti-nutritional factors (phytic acid and trypsin inhibitor), anti-oxidants level (phenol, total flavonoids and free radical scavengers), concentration of vitamins (A, B, C, D and E) and protein digestibility. The commercial samples of both ‘iru-woro’ and ‘iru-pete’ were more acceptable than the laboratory-fermented products. Similar trends were observed for stickness, texture, colour, odour and overall acceptance. Other proximate parameters (ash, crude fibre and fat) did not show any consistent trend when the concentration of ‘kuuru’ added increased. The concentrations of phytic acid and trypsin inhibitor in ‘iru-pete’ produced using 1:300 to 1:50 (w/w) of ‘kuuru’, increased from 6.99 mg/g to 10.43 mg/g and 45.51 mg/g to 60.44 mg/g, respectively. Increasing concentration of ‘kuuru’ decreased the level of antioxidants present in the fermented products from 1:300 w/w (0.64 mg/g to 0.38 mg/g) in total phenol, (0.86 mg/g to 0.22 mg/g) in total flavonoids and (91.75 mg/g to 73.32 mg/g) in DPPH. Increasing concentration of ‘kuuru’ led to significant reduction in the vitamins A content of the ‘kuuru’-fermented products. Similar trend of decrease was observed for vitamins C and E. The in-vitro protein digestibility of ‘kuuru’ fermented products ranged from 39.91% to 36.09%. This research paper confirms that ‘kuuru’ is not a suitable additive in the production of ‘iru-pete’.