The microbiology of ogiri production from castor seed ( Ricinus communis)

Abstract

The micro-organisms involved in the fermentation of castor seeds ( Ricinus communis) by the traditional method were enumerated and isolated. The effect of using pure cultures to ferment the seeds were also investigated. Using the surface spread plate technique and plate count agar, aerobic counts obtained after seven days of fermentation was 1·7 × 10 11 cfu g −1. Similarly anaerobic counts obtained on reinforced clostridial agar was 1·2 × 10 5 cfu g −1. Bacillus sp., Pseudomonas sp., Micrococcus sp. and Streptococcus sp. were isolated from fermenting castor seeds. The pH of fermenting castor seeds increased from 6·5 to 8·1 during the seven days of fermentation while the total titratable acidity decreased from 47 ml to 36 ml 0.1 N NaOH 100 g −1 sample. The use of pure isolates to ferment the sterile seeds showed that only Bacillus sp. could ferment the seeds in pure cultures.