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Please answer the following questions:

First question:                                                            (7 marks)

1- Describe a screening test for detection of Brucella abortus in a milk   

    sample.                                                                                  (3 marks)

2- Milk-borne viral diseases                                                    (3 marks)

3- Indicate True (T) or False (F) and correct the false one:

                                                                                (1 mark/ 0.5 for each)

a- Molds prefer growth at high water activity

b- Bang's method is used for control of tuberculosis in countries of   

    high incidence. 

Second question:                                           (6 marks/ 1.5 for each)

Indicate True (T) or False (F) opposite to the followings, giving details for the reason(s).     

1- Dioxins and Furans are environmental pollutant of dairy products.

2- Milk from antibiotic- treated animals should not consumed or used in dairy processing.

3- Entterococci are better indicator of sanitary quality than E. Coli (specially in heat treated food, frozen or dried foods.)

4- Prevention of high bacterial content at the site of production is the main step for clean milk production.

Third question:                                                           (6 marks)

1- How can you detect milk contamination with anaerobic microorganisms?                                                                    (2 marks)                                                                                                                                                                                                                                         

2- Mark (? ) for true and ( X ) for wrong, and then correct the wrong statement.                                                             (2 marks/ 0.5 for each)

a- Ropiness of milk occurs directly after milking due to presence of  

    fibrin and leucocytes.

b- Clostridia are responsible for deep holiness in raw milk cheese.

c- Milk of good keeping quality stands 3-4 days at 25.5 ?C without  

    change.

d- Catalase enzyme gives no indication about chronic mastitis.

3- Give reason(s) for the followings:                  (2 marks/ 0.5 for each)

a- Foam at the pasteurized milk kept at warm temperature.

b- Red spots on milk surface and red sediment of milk

c- Tests depending on developed acidity should not be used as sole  

    criteria for accepting or rejecting milk.

d- Addition of 0.1% alizarine to A.P.T. test.

Fourth question:                                                         (6 marks)

1-       Explain why milk is considered valuable and important food.                                                                                     

                                                                                                (2.5  marks)

2-       How can you confirm freedom of milk from preservatives to be used in manufacturing of cheese?                                  (2.5  marks)                                                                                         

3-       Give reason(s) for the followings:                (1 mark/ 0.5 for each)

- Fat % increases during summer months. 

-  Zeiss immersion refractometer is used for detection of    

   preservatives

                                                             Good Luck

                                       Professor Dr. Hossam Farouk Ahmed