Abstract

Mishkat, O. Karar Altayeb, Fatima A. Douda, Elniema A. Mustafa and Prof. Adil M. A. Salman*

ABSTRACT

This study was conducted to evaluate the microbiological quality of yoghurt purchased in Khartoum State during its shelf life and to compare the yoghurt produced in different factories. A total of 36 yoghurt samples were collected from December to February/2019-2020. Samples were collected from 9 groceries and 9 supermarkets with 18 samples for factory A and B in the three localities of Khartoum State. The samples were subjected to the total coliform count (TCC), tentative isolation of the Escherichia coli and Salmonella and the detection of pH and temperature values of yoghurt. By using the Most Probable Number Method (MPN) the TCC in day one of factory A was found 4.6±1.8cfu/ml and 315.2±105.2cfu/ml for factory B, whereas it was found 6.9±4cfu/ml for factory A and 1100 cfu/ml for factory B in day ten. There were significant differences in the TCC of day one and day ten between the two factories with p?0.05. The TCC in day one for the groceries and supermarkets in the State was 129.8cfu/ml and 190cfu/ml and increased in day ten to 551cfu/ml and 555cfu/ml, respectively. Statistically there were no significant differences between groceries and supermarkets in day one and day ten with p?0.05. The mean pH observed in these samples in day one for factory A was 5.6 and 5.2 for factory B, and decreased in day ten to 4.6, 4.4 for factory A and B, respectively. These values were above the yoghurt acceptable pH of Sudanese standard and metrology organization (SSMO) (4.5) in day one, but it decreased in day ten matching the SSMO with about 17 (48.6%) of samples. E. coli was detected in 12 (33.3%) of the samples. One sample was positive for both Salmonella and Escherichia coli. The refrigerator temperature of the groceries and supermarkets in the three localities was above the optimum storage temperature (5?). The highest ambient temperature in the groceries and supermarkets was detected in Bahri 39.5? and 38? in groceries and supermarkets, respectively. In conclusion the overall hygienic quality of yoghurt samples was lower than the limits recommended by the SSMO. It was recommended that all producers should maintain adequate hygienic practices to produce good quality and healthy yoghurt.