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Abstract
This work was conducted in a dairy plant in El-fayum governorate. It aimed to detect the sanitary quality of yoghurt as well as to detect the critical control points at which the dairy product under test may be contaminated.
25 samples each from raw milk, heated milk, mixing vat, worker’s hands, cultured milk, plastic packages, fresh and old yoghurt were collected regularly every week. All samples were examined for the presence of
1- Total colony count.
2- Thermoduric count (heated milk only).
3- Total coliform count.
4- Faecal coliform count.
5- Total Enterococci count.
6- Staphylococcus aureus count.
7- Total yeast and moulds count.
8- Escherichia coli.
9- Saphylococcus aureus.
9- Yersinia enterocolitica.
In addition, the raw milk and yoghurt samples were examined for their acidity % and the heated milk samples were examined for the efficiency of heat treatment using Storch’s test. The obtained results showed that:
Ι- Sanitary examinations:
• The mean values of acidity % were 0.15 ± 0.004, 0.71± 0.01 and 0.91± 0.01 in the examined raw milk, fresh and old yoghurt samples, respectively.
• All heat treated milk samples are efficiently heat-treated.
ΙΙ- Microbiological examinations:
• The mean values of the total colony count were 5.7 x 106 ± 1.2 x 106, 5.5 x 103 ± 2.4 x 103, 8.3 x 106 ± 3.3 x 106, 3.7 x 103 ± 1.6 x 103and 1.9 x 103 ± 5.9 x 102 cfu/ml in the examined raw milk, heated milk, worker’s hands, mixing vat, and plastic packages, respectively.
• Total coliforms were present in an average count of 1.4 x 104 ± 6.0 x 103, <3 ± 0, 2.5 x 103 ± 7.7 x 102, 6.2 x 103 ± 1.0 x 103, 3.7 x 103 ± 8.9 x 102, 2.7 x 102 ± 8.5 x 101, 5.4 ± 1.8 and 4.7 ± 1.4 coliforms/ml or gm., in the examined raw milk, heated milk, inoculated milk, fresh and old yoghurt, worker’s hands, mixing vat and plastic packages samples, respectively, while Faecal coliforms were present in an average count of 1.2 x 104 ± 4.7 x 103, <3 ± 0, 2.4 x 103 ± 7.7 x 102, 5.9 x 103 ± 1.0 x 103, 2.3 x 103 ± 7.9 x 102, 2.2 x 102 ± 8.1 x 101, 5.4 ± 1.8 and 3.2 ± 0.24 coliforms/ml or gm., in the same samples, respectively.
• The mean values of Enterococci count in the examined raw milk, heat treated milk, inoculated milk, fresh and old yoghurt, worker’s hands, mixing vat and plastic packages samples were 1.8 x 103 ± 4.4 x 102, <102 ± 0, 1.3 x 102 ± 4.9 x 101, 7.4 x 102 ± 3.1 x 102, 3.2 x 102 ± 1.8 x 102, 5.5 x 102 ± 3.1 x 102, <102 ± 0 and <102 ± 0 cfu/ml or gm., respectively.