Chapter 7 Milk and Dairy Products

Question 1

What are the origins of contamination of milk?

Answer 1

• Interior of the udder
• Udder and teat surfaces
• Equipment

Question 2

What are some methods to minimize pathogen contamination in milk?

Answer 2

• Cleaning and disinfecting the teat and udder surface

- Keep cows on pastures (field)

Question 3

What could cause the presence of coliform on/in the udder?

Answer 3

• Fecal contamination of udder
• Mastitis
• Contamination from unsanitary equipment.

Question 4

What are some hazardous microorganisms associated with milk?

Answer 4

• Bovine tuberculosis
• Campylobacter jejuni
• Salmonella spp.
• EHEC/VTEC

Question 5

What are the 6 processes involved in ice-cream processing?

Answer 5

• Blending
• Homogenization
• Pasteurization
• Cooling and Aging in vat
• Flavoring
• Freezing

Question 6

What role do sucrose and lactose play in protecting spoilage bacteria in ice-cream?

Answer 6

Sucrose and lactose may act as cryoprotectant to bacteria.

Question 7

What are some processes involved in the production of cheese?

Answer 7

• Milk standardization
• Milk clarification
• Heating and cooling (pasteurization)
• Acidification and starter cultures.

Question 8

What are some methods of milk clarification?

Answer 8

• Bactofugation

- Microfiltration

Question 9

Why is it important to minimize the presence of bacteriophage in making cheese? State 1 method to inhibit the actions of bacteriophage.

Answer 9

• Bacteriophage causes lysis of starter culture, leading to culture failure.
• Can be minimized by adding phosphates. Phosphates chelates divalent cations to inhibit absorption of phage onto lactic acid bacteria.

Question 10

What are some microorganisms that may cause defects in cheese?

Answer 10

• Presence of yeasts/Mold
• Coliforms
• Bacillus subtilis.

Question 11

What is the most significant bacterial hazard in dried milk?

Answer 11

Salmonella.