THE EFFECTS OF GINGER (Zingiber officinale) ON THE MICROBIAL LOAD OF A NIGERIAN TRADITIONALLY FERMENTED MAIZE PASTE (OGI)

Various concentrations (1, 5 and 10 %) of milled oven-dried ginger and fresh ginger were incorporated into ogi at the beginning of fermentation. Physicochemical and microbiological changes were noted during fermentation. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) of ethanolic ginger extract on selected bacterial isolates were also investigated. Physicochemical parameters such as pH and Titratable acid were analysed while microbiological changes were observed by inoculation of the various concentrations on Nutrient Agar, Salmonella-Shigella agar using the spread plate method. The pH of ogi samples decreased steadily and ranged between 4.11 at the beginning of fermentation and 5.74 at the end of fermentation and Titratable acidity (TA) ranged between 0.22 at the beginning of fermentation (0 hr) and 0.75 % at the end of fermentation (72 hrs). The total viable and coliform counts ranged between 2.8 and 7.3 (x10 5 cfu/ml) and 2.8 and 5.9 (x10 5 cfu/ml) while the Salmonella-Shigella agar counts ranged between 0 and 3.5 (x10 2 cfu/ml) from the beginning of fermentation to the end. Samples containing no ginger (D) had the highest coliform counts of 5.9 x10 5 cfu/ml and the highest total viable count of 7.3x10 5 cfu/ml. Samples FC, DC and D were the only ones with recorded bacteria count on Salmonella-Shigella agar. Sample DB (5% dry ginger) had the lowest coliform counts, had the lowest total viable count and did not have any growth on Salmonella-Shigella agar. Shigella dysenteriae had the lowest MIC and MBC of 3 mg/ml while Salmonella typhi had the highest MIC and MBC of 5 mg/ml. This study revealed that incorporation of ginger into ogi significantly reduced its microbial load during fermentation which may lead to an improvement in its nutritional quality and the prevention of some food-borne diseases.