Assessment of the Microbiological Status of Yoghurt Sold in Owerri, Imo State, Nigeria

Abstract

The assessment of the microbiological status of samples of yoghurt sold in Owerri, Imo state, Nigeria, was carried out to ascertain the microbiological fitness of the yoghurt samples for consumption. The yoghurt samples were collected from areas spanning three local governments in Owerri. Ten samples of commercial brands of yoghurt drinks was collected and analyzed bacteriologically by pour plate method using Nutrient Agar for heterotrophic bacteria, MacConkey Agar for total coliform and MacConkey Broth for fecal and thermo-tolerant coliform bacteria by Most Probable Number (MPN) technique and mycologically on Sabouraud dextrose Agar for fungi. Data from analysis were analyzed using ANOVA. Determination of the pH of the yoghurt samples was done and the results showed that the pH values ranged from 4.28 to 4.79. the results of the total heterotrophic bacteria count were from 5.07.1bc to 9.07.1a×105CFU/ml, while the total coliform bacteria ranged from 1.70.5ab to 3.61.2ab×104CFU/ml and the thermo-tolerant coliform bacteria ranged from 11 to 120(MPN) 100-1. The total fungal count ranged from 2.91.6b to 10.33.6a×104CFU/ml. The pH determination revealed that the isolates are acidophile because the pH of the yoghurt samples were in the acidic range. There was a significant difference at P >0.05 and the difference were separated using the least significant difference (LSD).  Five bacterial isolates were identified included: Staphylococcus aureus, Escherichia coli, Streptococcus spp., Lactobacillus bulgaricus and Serratia marcesecens. The fungal genera identified were Candida albicans, Aspergillus niger, Mucor spp. and Saccharomyces cerevisiae. The isolation of both fungal and bacterial organisms known to be enteric pathogens is suggestive of  faecal contamination and by implication a serious public health problem due to the health hazards they pose to consumers. The result of this study therefore indicated poor Microbiological qualities of commercial yoghurts sold in Owerri at the time of this research. Therefore, the attention of the appropriate government agencies is needed to ensure that adequate hygiene is maintained during preparation, processing, storage and distribution of high quality yoghurt products to avert public health challenges.