Evaluation of starters for the fermentation of African oil bean (Pentaclethra Macrophylla Benth) seeds

Abstract

PurposeThe purpose of this paper is to examine pure culture isolates from traditionally fermented product of African oil bean seeds (ugba) with a view to identifying the appropriate starters.Design/methodology/approachThe isolates were purified and characterized, and used singly and in combination to ferment freshly prepared oil bean seed slices for 72 h at 37 ○C. The pH and microbial load of fermenting beans were monitored daily, and organoleptic tests using semi‐trained panelists were employed to assess the fermented products based on quality attributes of flavour, appearance, texture and overall acceptability.FindingsThe isolates included Bacillus subtilis, Bacillus licheniformis and Pseudomonas fluorescens. Total viable counts ranged from 1.3 × 107‐9.3 × 109 cfu/g, 7.0 × 106‐4.0 × 109 cfu/g, and 3.0 × 106‐1.5 × 109 cfu/g, respectively for the three isolates; while counts for the mixed culture fermentation ranged from 7.0 × 106‐1.72 × 1010 cfu/g. The mixed culture fermentation gave the best rated product, indicating a synergy among the isolates. The pH values increased steadily in the samples fermented by Bacillus sp. and the mixed culture organisms, showing that the production of ugba follows alkaline fermentation pattern.Research limitations/implicationsThe African oil bean seed fermentation is a bacterial mixed culture and alkaline fermentation. The major organisms involved are B. subtilis and B. licheniformis, while the P. fluorescens was insignificant.Originality/valueMost of the local fermentations in Africa, including oil bean fermentation, are still at the wild, natural inoculation level. The present study has helped in understanding of the fermentative organisms involved in Pentaclethra seed fermentation, and gave insight into an optimized ugba production.