Microbial assessment and quality evaluation of ogi during spoilage

The changes during the fermentation of ogi, a cereal-based traditional lactic acid-fermented weaning food were studied up to the spoilage stage. Ogi off-odour was first noticed at the fourth day of fermentation ( including 24 h steeping). Yeast isolates such as Candida valida, C. krusei, Geotrichum candidum and bacteria like Lactobacillus brevis, L. plantarum, Pediococcus pentosaceus, Bacillus subtilis, Brevibacterium linens, Br. oxydans and other two Brevibacterium spp. dominated the fermenting mash at the spoilage stage. The brevibacteria contributed most significantly to ogi off-odour. Ogi samples inoculated with lactic acid bacteria increased acidity and product acceptability over the time of fermentation. The pH, titratable acidity, dissolved hydrogen sulphide and the presence of brevibacteria appear as good indices for monitoring spoilage. Hydrogen sulphide (H2S) levels appear to be the most useful of the parameters studied. No coliforms and clostridia were identified during spoilage.