Microbiological Assessment of Selected Yoghurt Drinks Retailed in Ilorin Metropolis, North-Central Nigeria.
ABSTRACT Yoghurt is a fermented dairy product that is widely consumed in many parts the world including Nigeria. In this study, eight different blends of yoghurt namely Abide, Hollandia, D-Matrix, Fresh, Basako, Ojoma, Savanna and Dudu yoghurts were purchased in duplicates at different locations in Ilorin metropolis and assessed for their microbiological quality. The physicochemical parameters as well as the microbial flora of the yoghurt samples were assessed. The physicochemical parameters analyzed included pH, titratable acidity, moisture content, total solids and ash content. The pH values ranged from 3.51-4.25 (mean of 3.83), the moisture content varied between 75.3-85.8% (Mean of 79.9%) while the total solids content varied from 14.2-24.7% (Mean of 20.1%) and the ash content 0.75-2.54%. (Mean of 1.51%). Four different growth media namely NA (for bacteria), PDA (for fungi), MRS (for Lactic acid bacteria) and MacConkey agar (for enteric bacteria) were used for the isolation of microorganisms from the yoghurt drinks. The microbial analysis revealed the presence of one or more contaminants in each of the yoghurt blends. Six (6) bacterial species were isolated from the eight yoghurt samples namely Serratia marcescens, Proteus mirabilis, Staphylococcus aureus, Micrococcus luteus, Streptococcus thermophilus and Lactobacillus bulgaricus. Five (5) fungal species were also isolated from them. The isolated fungi were Rhizopus stolonifer, Aspergillus fumigatus, Aspergillus flavus, Mucor racemosus and Mucor spp. The total microbial count gave an average bacterial count of 1.78 x 103 CFU/ml and a fungal count of 0.60 x 103CFU/ml. The LAB enumeration on the other hand had an average count of 2.51 x 103CFU/ml. All the analyzed batches of the 8 yoghurt blends presented inadequate microbiological quality and standards with respect to ability to provide probiotic benefits due to very low LAB counts but they were considerably safe for consumption considering their very low levels of microbial contaminants.