Effect of Wood Charcoal Powder on Rate of Microbial Production of Lactic Acid in Dehulled and Undehulled Vigna unguiculata Pastes

Abstract

Effect of Wood Charcoal Powder (WCP) on rate of microbial production of Lactic Acid (LA) in ground dehulled and an undehulled Vigna unguiculata (cowpea) paste was studied. The pastes were analysed for proximate compositions, energy values, tannin contents and microbial loads. Later, 4.0 g pastes were treated with incremental concentrations (0.03-0.05 g) of WCP diluted with 50 mL distilled water and fermented for 2 h at ambient temperature (29.5 ± 2.0ºC). Results showed that decortication of cowpea significantly reduced (p<0.05) the crude protein, crude fibre, crude fat and tannin contents as well as energy value and microbial loads. Fermentation produced ethanol and LA. The WCP inhibited LA production in dehulled cowpea paste, whereas LA fermentation continued unhindered in Undehulled Cowpea Paste (UCP). A WCP-tannic acid-cellulose interaction study suggested that WCP interacted more with the fibre and tannin components of UCP thereby reducing the amount that would have bound the fermentative microorganisms. In conclusion, wood charcoal inhibited microbial production of lactic acid in ground dehulled cowpea paste.