Microbial Assessment of Yoghurts Sold in Amawbia, Nigeria

摘要

Five brands yoghurts designated A, B, C, D and E were obtained and used for assessing their microbial quality. A ten-fold serial dilution was carried out and appropriate dilution used to inoculate duplicate plates of SDA, Eosin methylene blue, MacConkey and Nutreint agars. Discrete colonies that developed were purified and stored on agar slant at 4℃. The pH of the samples ranged from 5.6 to 6.0. In the total coliform count, sample A recorded no count while others had count from 2.0 to 5.0 x 10~(2)cfu/ml. The total viable bacterial and fungal counts were 6.0 to 18.0 x 10~(4) and 1.0 to 6.0 x 10~(3)cfc/ml, respectively. Five fungal genera were obtained as Aspergillus, Penicillium, Fusarium, Mucor, Geotricum, Neurospora and Absidia. Mucor species occurred in all the samples while Fusarium species occurred only in sample B. Among the samples, yoghurt sample B harbored a greater percentage of the fungal isolates. Samples C and D had the least number of fungal of three (3) each. The bacterial isolates obtained include species of Staphylococcus, Lactobacillus, Escherichia, Bacillus, Pseudomonas and Klebsiella. Sample B also recorded the highest number of bacterial isolates. The genera Bacillus occurred in all the yoghurt samples whereas Lactobacillus and E.coli occurred only in two yoghurt samples each.