الفهرس 
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Abstract
Present work studied the incidence of heavy metal either toxic or essential and aflatoxins in raw cow’s milk and some dairy products. Therefore, 120 samples from raw cow’s milk and some different dairy products including (Cream, Cooking butter, Kareish cheese, Damietta cheese, and yoghurt) 20 of each type, were collected in polyethylene plastic bags, from different supermarkets and groceries, in Alexandria city.
The obtained results summarized in the following items.
7.1. Heavy metal content:
1. Lead level in examined cow’s milk and some dairy products.
Lead was detected in 50, 35, 50, 55, 60 and 40 % of examined samples of raw cow milk, cream, cooking butter, Kareish cheese, Damietta cheese and yoghurt with mean values of 0.33±0.049, 0.18±0.037, 0.28±0.071, 0.27±0.021, 0.26±0.032 and 0.29±0.043 ppm, respectively.
According to Egyptian standard (2010) stated that lead level in raw milk and other dairy products should not exceed 0.02 ppm, there are 50, 35, 50, 55, 60 and 40% of positive samples in raw milk, cream, cooking butter, Kareish cheese, Damietta cheese and yoghurt samples were exceeding permissible limit set by Egyptian standards.
2. Cadmium level in examined cow’s milk and some dairy products.
Cadmium was detected in the examined samples of raw cow milk, cream, cooking butter, Kareish cheese, Damietta cheese and yoghurt at incidence of 45, 40, 25, 35, 30 and 35% with mean values of 0.039±0.007, 0.041±0.007, 0.042±0.011, 0.030±0.004, 0.075±0.013 and 0.044±0.008 ppm.
According to Egyptian Standards (1993) which stated that cadmium level must not exceed 0.05 ppm there are 15, 15, 5, 20 and 10% of examined raw cow milk, cream, cooking butter, Damietta cheese and yoghurt were exceeding the permissible limits. While, all positive samples of Kareish cheese were below permissible limit.
3. Aluminum level in examined cow’s milk and some dairy products.
Aluminum was detected in 35, 45, 35, 25, 30 and 45 % of examined raw milk, cream, cooking butter, Kareish cheese, Damietta cheese, and yoghurt samples with mean values of 0.031±0.003, 0.413±0.101, 0.274±0.054, 0.334±0.118, 0.21±0.091 and 0.131±0.027 ppm, respectively.
According to Pennington (1987) which stated that Al content in milk and dairy products not exceed 0.5 ppm, there are 35, 5, 5, and 5% of examined cream, cooking butter, Kareish cheese, and Damietta cheese samples were exceeding permissible limits. All positive samples of raw cow’s milk and yoghurt were below the permissible limits.
4. Copper level in examined cow’s milk and some dairy products.
Copper was found in all examined samples of raw milk, cream, butter, Kareish cheese, Damietta cheese, and yoghurt with mean values of 0.69±0.06, 1.89±0.08, 1.82±0.21, 1.20±0.03, 1.75±0.20 and 0.78±0.06 ppm, respectively.
According to the Egyptian Standard (1993) which stated that copper must not exceed 0.1 ppm; all examined raw milk, cream, cooking butter, Kareish cheese, Damietta cheese and yoghurt samples were exceeding this permissible limit.
5. Zinc level in examined cow’s milk and some dairy products.
Zinc was found in all examined samples of raw milk, cream, cooking butter, Kareish cheese, Damietta cheese and yoghurt samples with a mean values of 2.17±0.26, 3.44±0.06, 4.04±0.11, 2.73±0.18, 3.20±0.23 and 2.66±0.13 ppm, respectively.
According to the Egyptian Standard (1993) which stated that zinc should not exceed 20 ppm, all examined of raw milk, cream, cooking butter, Kareish cheese, Damietta cheese and yoghurt samples below this permissible limit.
7.2. Mycotoxins (AFM1 and AFM2):
AFM1 was detected in 15, 10, 15, 15 and 20 % of examined raw cow milk, cream, cooking butter, Kareish cheese and Damietta cheese with mean values of 0.078±0.05, 0.42±0.27, 0.33±0.09, 0.29±0.09, and 0.46±0.16 ppb, respectively. While, AFM1 failed to detect in examined yoghurt samples.
According to Egyptian standards (2010) stated that AFM1 should not more than 0.05 ppb in milk products, there are 5, 10, 15,5, and 20% of examined raw cow milk, cream, cooking butter, Kareish cheese and Damietta cheese were exceeding permissible limit established by Egyptian standards.
AFM2 was detected in 10, 10, 5 and 10 % of examined cream, cooking butter, Kareish cheese and Damietta cheese with mean values of 0.14±0.07, 0.18±0.09, 0.121±0.00 and 0.12±0.01 ppb, respectively. While AFM2 could not detected in examined raw cow’s milk and yoghurt samples.
According to Egyptian standards (2010) stated that AFM2 should not more than 0.05 ppb in milk products, there are 10, 10, 5 and 10% of examined cream, cooking butter, Kareish cheese and Damietta cheese were exceeding permissible limit established by Egyptian standards.
7.3. Effect of milk processing to dairy products on heavy metals and Aflatoxins content:
Lead, cadmium, Aluminum, copper and Zinc in cheese either Kareish or Damietta cheese were higher than those in cream, butter and their products.
Boiling off has great effect on heavy metal content other than other treatments (fat separation and churning) as cause largest reduction percent in heavy metals content. While, fermentation has a little effect on heavy metal content.
AFM1and AFM2 concentration in cheese either Kareish or Damietta cheese were higher than those in cream, butter and their products. Fermentation and Boiling off has a significant effect in reducing concentration of AFM1 and AFM2 amounted to 91.8 and 100%.