Assessment of Microbiological Quality of Yogurt Sold By Street Vendors in Onitsha Metropolis, Anambra State, Nigeria

Four brands of yogurt sold by street vendors in Onitsha Metropolis, Anambra State,
Eastern Nigeriia were sampled, the pH was determined and microbiological assessments
were conducted in order to ascertain the total heterotrophic bacteria, coliforms and yeast in
the samples (A – D) during a seven day period. The results revealed that values of pH
monitored varied from 3.69 – 4.50 while a total of five bacteria species belonging to
Escherichia coli, Staphylococcus aureus, Streptococcus, Lactobacillus and Bacillus
species, and three fungi species belonging to Aspergillus, Rhizopus and Saccharomyces
were isolated from the samples. Sample B had the highest mean heterotrophic bacteria
count with a value of 6.1 x 105 cfu/ml. Statistical analysis of heterotrophic bacteria count
among the 4 sample groups had p-value =0.0000374. There is a significant difference in
the heterotrophic bacteria count among the groups. Low titre values of starter cultures were
recorded in the control samples. Escherichia coli, an indicator of coliform was detected in
all the samples and the value of 4.4 x 105 cfu/ml was observed in sample B. Coliforms, S.
aureus, Bacillus species and fungi were not detected from control samples purchased
directly from the producing companies. Statistical analysis of coliform count in the four
groups had p-value=0.529296. There was no significant difference in the coliform count
among the 4 sample groups at α =0.05 and p-value =0.529296. The findings suggest that the yogurt traded by street vendors in Onitsha Metropolis has poor microbiological quality
control. This poses danger to public health. Therefore, attention of the appropriate
government agencies and manufacturers is needed to ensure that sale of yogurt by
vendors is done in most appropriate condition and in a mobile refrigerator to maintain
adequate temperature, thereby, reduce contamination.