Evaluation Of The Quality Of Milk Sold In Khartoum State, Sudan

This study was carried out between August 2003 and March 2004. One hundred and twenty milk samples were collected from supermarkets in Khartoum State. Sixty milk samples were collected during summer and other 60 during winter from the same supermarkets. The milk samples were examined for microbial, chemical and physical characteristics. Total bacterial count, sporeforming bacterial count and coliform count are determined. Enumeration, isolation and identification of E. coli, S. aureus, Salmonella spp. and the presence of Brucella as detected by milk ring test were also estimated. The criteria used for identification of the isolates were reaction to Gram's stain, morphological appearance, cultural characteristic and biochemical tests. The chemical characteristics included the determination of pH, fat, protein, total solids and ash contents, phosphatase test and formalin test. However, the physical properties of milk were determined by measurement of temperature, acidity and freezing point. The present study revealed high average of total bacterial count (5.63 × 109 ± 2.87 × 1010 cfu/ml) was found in milk samples. Moreover, during summer season, the total bacterial count of milk (1.04 × 1010 ± 4.01 × 1010 cfu/ml) was higher than winter (9 × 108 ± 2.51 × 109 cfu/ml). Staphylococcus aureus was detected in 46.7% of the milk samples with mean count of 4.92 × 104 ± 1.29 × 106 cfu/ml. During summer the 8 mean count was 7.44 × 105 ± 1.66 × 106 cfu/ml, which was higher than the count during winter (1.61 × 105 ± 2.3 × 105 cfu/ml). Escherichia coli was detected in 2.5% of the milk samples with a mean of 6.0 × 105 ± 7.94 × 105 cfu/ml and coliform bacteria were detected in 82.5% with a mean of 3.32 × 106 ± 1.43 × 107 cfu/ml. Also during summer the mean of coliform bacteria was 5.15 × 106 ± 2 × 107 cfu/ml, which was higher than during winter (1.45 × 106 ± 3 × 106 cfu/ml). Sporeforming bacteria were detected in 32.5% of the milk samples with a mean of 4.81 × 106 ± 1.4 × 107 cfu/ml. During summer the mean of sporeforming bacteria (7.15 × 106 ± 1.79 × 107 cfu/ml) was higher than during winter (1.45 × 106 ± 3 × 106 cfu/ml). There were no Salmonella spp. in any of the milk samples collected in the present study. Milk ring test for brucella showed that 44.1% of the milk samples were positive for brucella. Moreover 54.4% of which were detected during winter and 45.6% were found during summer. Milk samples revealed mean total protein value of 2.97 ± 0.495%, during summer it was 3.005 ± 0.53% and it was 2.9444 ± 0.46% in winter. The mean fat content was 3.695 ± 1.124% and during summer and winter were 3.943 ± 1.02% and 3.447 ± 1.18%, respectively. Mean total solids value was 12.614 ± 1.72% and during summer and winter were 12.27 ± 1.84% and 12.96 ± 0.52%, respectively. The mean ash content was 0.563 ± 0.106%. In summer and during winter they were 0.575 ± 0.085% and 0.545 ± 0.115%, respectively. The mean pH value was 6.498 ± 0.301%, while during summer and winter they were 6.3 ± 0.32% and 6.663 ± 0.157%, 9 respectively. Also during this study 44.1% of the milk samples were positive to phosphatase test. All the milk samples (100%) were found to be negative to the presence of formalin. The present study revealed that the mean temperature of the milk samples was 25.32 ± 15.19ºC. During summer and winter seasons the temperature were 29.78 ± 15.73ºC and 20.85 ± 13.74ºC, respectively. It was found that the mean acidity of the milk samples was 0.1756 ± 0.0287%. Moreover, during summer the acidity was higher (0.193 ± 0.03) than recorded during winter (0.158 ± 0.018%). The mean freezing point was found to be – 0.535 ± 0.0339. Conclusions and recommendations for improvement of hygienic quality of marketed milk in Khartoum State were suggested. Sanitary standards should be established in this country so as to control milk production and marketing. Further studies should be done to evaluate safe and good supply of consumed milk