Microbiology of natural fermentation of cowpea and groundnut for Dawadawa production

Abstract

Traditionally, locustbean is fermented naturally for dawadawa production. Scarcity of locustbean indicated a need for using other legumes as substitutes for producing dawadawa. The feasibility of using cowpea and groundnut was therefore investigated. The microorganisms associated with natural fermentation of cowpea and groundnut were isolated in three separate fermentations lasting 72h. Sensory techniques were used to evaluate the flavour of the finished product. Lactobacillus casei and L. fermentum were responsible for the fermentation of cowpea. Corynebacteria equi, C. xerosis and Mycobacteria segmeatis were identified as the most predominant microorganisms during groundnut fermentation. A significant increase (P<0.05) in titratable acidity from 1.05 mg/g to 6.80mg/g and from 1.20mg to 6.60mg/g was observed for cowpea and groundnut fermentation respectively. As fermentation progressed, pH increased significantly (P<0.05) from 7.04 to 7.83 in groundnut, but decreased significantly (P<0.05) from 7.14 to 6.60 in cowpea. Changes in pH suggest that proteolytic activity was dominant in groundnut fermentation. Bacillus species, primarily responsible for the flavour in naturally fermented locustbean, were not detected in fermented cowpea and groundnut. Dawadawa made from cowpea and groundnut were less acceptable to sensory panelists than dawadawa made from locustbean. Overall, cowpea and groundnut were not suitable for producting dawadawa with acceptable organoleptic quality.


KEY WORDS: Natural fermentation, titratable acidity, Lactobacillus, Corynebacteria, Mycobacteria.


Global Jnl Pure & Applied Sciences Vol.10(2) 2004: 291-296