Proximate Composition and In-vitro Starch/Protein Digestibility of Bambara Groundnut Flour Fermented with Lactic Acid Bacteria (LAB)-Consortium Isolated from Cereals

Abstract

The effect of lactic acid bacteria (LAB) consortium fermentation on the proximate and in-vitro starch and protein digestibility of bambara groundnut flour was evaluated. Bambara groundnuts were processed into flour and fermented with LAB consortium previously isolated from maize (Lactobacillus plantarum WCFS1+Lactobacillus rhamnosus GG, ATCC53/03+Lactobacillus nantensis LP33+Lactobacillus fermentum CIP102980+Lactobacillus reuteri DSM 20016) and from sorghum (Pediococcus acidilactici DSM 20284+Lactobacillus fermentum CIP102980+Lactobacillus brevis ATCC14869+Lactobacillus nantensis LP33+Lactobacillus plantarum WCFS1). The sample was also fermented naturally for comparison. The results showed significant (p<0.05) increase in the moisture, ash and protein contents of the bambara groundnut flour as fermentation time increased. The lipid and crude fibre contents decreased significantly (p<0.05) with the increasing fermentation time in all the samples. The carbohydrate content decreased gradually from 50.66 ± 0.23% to 44.96 ± 0.10%. The in-vitro starch digestibility increased significantly (p<0.05) with increasing fermentation periods from 42.48 ± 0.01% to 50.36 ± 0.02%. The in-vitro protein digestibility increased significantly (p<0.05) from 68.70 ± 1.73% to 85.24 ± 1.21%. There was gradual increase in the bacteria load of the sample as fermentation time increased. However, fungal growth was only observed in natural fermentation. The occurrence of the isolates showed that the starter organisms were the only organisms isolated from the consortia fermentation set up while the natural fermentation have mixed microbial growth. This study has shown the effectiveness of LAB-consortium fermentation in improving the nutritional quality and the in-vitro starch and protein digestibility of flours from bambara groundnut.