الفهرس 
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Abstract
Five different samples were collected from hard and semi-hard cheeses imported from different sources in Port Said governorate (Gouda, Edam, Cheddar, Gruyère, and Roquefort cheese). Chemical, microbiological and sensory evaluations were performed.The main objective of this study was the chemical, microbiological and sensory evaluation of the imported hard and semi-hard cheese taken from the local market. Mycotoxins were detected according to the Egyptian standard specifications, and microbial enzymes that decompose cheese. The samples were examined chemically for fat content, moisture, salt, lactose, protein, and percentage of fat in the dry matter. Moreover, the microbial load was examined for the total number of bacteria, Staphylococcus aureus, Salmonella, Shigella, Coliform, Clostridium and the total number of fungi The obtained results can be summarized as follow.
1-Chemical examination of cheese sample:
This study was conducted on the chemical composition of hard and semi-hard cheese (Gouda, Edam, Cheddar, Gruyère, Roquefort) and the highest value of fat was in Gruyere cheese 34.98% and the lowest value was in Gouda cheese 21.22%. The highest percentage of moisture content in Gouda cheese was 52.85% and the lowest percentage in Gruyere cheese was 35.87%. The highest percentage of salt was in Roquefort cheese 3.56% and the lowest in Gruyere cheese 1.42%.
The results also showed that the percentage of lactose had the highest value in Gruyere cheese 2.618%, the lowest value in edam cheese 1.082, the highest percentage of protein in Gruyere cheese 28.95%, and the lowest value was in blue cheese 20.01%The results showed that the pH percentage was the highest value in Roquefort cheese 5.90% and the lowest value was in Edam cheese 4.89%. The percentage of fat in the dry matter was the highest value in Gruyere. cheese 54.55% and the lowest value was in Gouda cheese 45%
3- Microbiological evaluation of cheese samples:
1-This study dealt with the total number of bacteria for hard and semi-hard cheese samples. The total number of bacteria reached the maximum value in Roquefort cheese (3105 cu ft / g) and the minimum value was 585 cu ft / g in Cheddar cheese. 2-The results showed the presence of coliform bacteria in all samples except blue cheese. Salmonella and Shigella were not found in all samples. All cheese samples did not contain Staphylococcus or Clostridium
3-Detection of mycotoxins according to the Egyptian standard
All hard cheese samples were examined to ensure that they are free of mycotoxins and were negative. These results were in conformity with the Egyptian standard specifications for pollutants This study shows that the microorganisms present in imported hard cheese degrade the protein in all Microbial enzymes that decompose imported chees
It also showed that microorganisms in all imported hard cheeses decompose lactose and produce acid and gas, except for blue cheese.
4-Sensory evaluation:
The sensory properties of the examined hard cheese showed that the color degrees ranged between 4.61 and 5.00 in Roquefort and Gouda, which was 5.1 in Gouda cheese. The highest value of appearance was 10.00 in Gouda, Edam and Gruyere cheese, respectively. The lowest value was 9.67 in Roqueford cheese. The texture scores range from 36.00 to 39.92 in Roquefort and Gruyere cheeses, respectively. The total sensory evaluation was 86.05, 86.66, 94.18, 86.83 and 99.73 in blue cheese, gouda, edamame and cheddar.