Fermentation of single and mixed substrates of lima bean seeds (<i>Phaseolus lunatus</i>) and African locust bean seeds (<i>Parkia biglobosa</i>)

Abstract

The use of single substrate of leguminous seeds for condiment production has been shown to have deficiency and imbalance in nutrient composition. This research was designed to determine possibility of the use of Lima beans and African Locust bean seeds as mixed substrates for condiment production. African locust bean seeds, Lima bean seeds as well as their mixed substrates were fermented for 72 hours. The physicochemical properties, microbiological analysis, proximate composition and anti-nutritional factors were thereafter determined for the three substrates. Five genera of bacteria (Bacillus subtilis, B. polymyxa, Lactobacillus casei, Leuconostoc mesenteroides, Micrococcus rubens and Staphylococcus aureus) and five genera of fungi (Aspergillus flavus, Penicillium expansum, Mucor mucedo, Rhizopus stolonifer and Saccharomyces cerevisiae) were isolated from the fermented substrates in this study. Bacterial counts (5.8 to 7.8 Cfu/g) and fungal counts (2.4 to 3.5 Sfu/g) observed in mixed substrates were lesser than their single substrates. Moreover, steady increases were observed in protein (36.86 –40.48%), fat (7.58 – 13.60%), moisture (8.74 – 9.07%) and ash (1.69 – 2.81%) contents of the mixed substrates as fermentation days progressed. Reductions in the anti-nutritional contents were also observed in the mixed substrates. This study showed an improvement in the nutritional quality and reduction in the antinutritional contents of the blended African locust bean seeds and Lima bean seeds when explored as mixed substrates, and thus, could improve the use of Lima bean seeds which are among the underutilized legumes.

Keywords: Legumes, Condiments, African locust beans, Lima beans, Nutritional quality