Chemical and Microbiological Evaluation of Plain and Fruit Yoghurt in Khartoum State, Sudan

This paper had been presented for promotion at the university of Khartoum. To get the full text please contact the other at Ibtisammohamed@hotmail.comThis study was conducted to evaluate the quality of yoghurt supplied to consumers from retail outlets in Khartoum State. Yoghurt samples (144 samples), which represent three different manufacturers (A, B and C) beside traditional producers (T) were collected. The samples included 96 plain yoghurt samples and 48 fruit yoghurt samples. All yoghurt samples were analyzed for chemical parameters (total solids, SNF, fat, protein, ash %, titratable acidity and pH) and the microbiological tests (total bacterial count, coliform count and the yeast and molds count). The means for total solids %, solids non-fat (SNF), fat, protein, ash % and pH for the plain yoghurt samples were 14.04±1.83, 10.86±1.53, 3.18±1.01, 3.44±0.58, 0.678±0.146 and 4.62±0.10, respectively. Whereas for the fruit yoghurt samples the means were 21.70±1.34, 19.70±1.27, 2.00±0.62, 3.90±0.50, 0.661±0.087 and 4.68±0.12, respectively. The means of microbiological measurements for the plain yoghurt samples were log 9.10±9.86, log 4.03±4.41 and log 4.09±4.57 for the total bacterial count, coliform count and yeast and molds count, respectively. Whereas in the fruit yoghurt samples the means were log 8.63±9.99, log 3.59±4.15 and log 3.15±3.64, respectively. Results obtained revealed significant variations (pc 0.001) between samples obtained from different manufacturers in their chemical composition. One hundred and thirty eight of collected samples (96.5%) were found satisfying the international standard for solids non-fat content, however, 73 yoghurt samples (50.7%) were found to have a lower fat content than the standard. In the microbiological parameters tested, the total bacterial count and yeast and molds count were not significantly different between different manufacturers. The coliform count of samples varied significantly (ps 0.001) between manufacturers and with a significance higher (ps 0.05) coliform count in samples collected from traditional manufacturers than that collected from modem manufacturers