Chapter 2 Meat and Meat Products

Question 1

What causes a lower pH in meat?

Answer 1

Glycolysis. During death, major parts of the tissue undergoes anaerobic metabolism. Glycogen is converted into lactic acid via glycolysis.

Question 2

Why is the pH more neutral at the surface of meat compared to the meat below the surface?

Answer 2

At the surface of the meat, the cells are able to undergo aerobic metabolism from the atmospheric oxygen, therefore lactic acid is not produced. But below the surface, lactic acid accumulates as the cells are unable to get access to oxygen.

Question 3

What are the factors that may affect the pH of meat?

Answer 3

• The location of the cut (near or far from the surface).

- Glycogen content which is dependent on pre-slaughter conditions such as starvation or stress.

Question 4

What are the five (5) steps of the primary processing of meat?

Answer 4

• Washing
• Stunning and Bleeding
• Skinning
• Eviscerating
• Trimming and washing

Question 5

What are the two methods of thermal decontamination?

Answer 5

By using 70-90C water or saturated steam.

Question 6

What are the disadvantages of chemical decontamination using organic acids?

Answer 6

• May result in corrosion and sensory change

- Bacteria may develop acid resistance.

Question 7

What temperature does warm spoilage occur?

Answer 7

> 15C

Question 8

What is bone-taint? What are the microorganisms responsible for bone-taint? How do we prevent it?

Answer 8

• Bone taint is the development of putrid and sour odor in the deep part of a meat tissue.
• The microorganisms responsible are: Enterobacteriaceae, and Clostridia.
• Temperature control, adequate resting.

Question 9

What causes DFD meat?

Answer 9

Conditions that cause glycogen depletion, such as starvation or stress.

Question 10

What causes green discolorations in vacuum or MAP packaging?

Answer 10

• Formation of sulfomyoglobin by S. putrifaciens.

Question 11

What are prions? Describe their dangers, and how to avoid them.

Answer 11

A prion is a protein that can cause Bovine Spongiform Encephalopathy (BSE), commonly found in bovine. It is resistant to heat, disinfectants, UV radiation and ionizing radiation.

Prevention: Inactivated by steam sterilization 133C at 3 bar pressure for 20 minutes. Avoid using high risk materials such as brain, eyes, spinal cords, nerve tissue, and lymph nodes for consumption.

Question 12

What are the common pathogens that causes food spoilage and food poisoning in meat?

Answer 12

• E. coli (O157:H7), Enterohemorrhagic E. coli.
• Salmonella sp.
• Clostridium botulinum
• Clostridium perfringens
• Listeria monocytogenes
• Staphylococcus aureus.

Question 13

What are the two parasites discussed in this chapter?

Answer 13

• Toxoplasma gondii

- Trichinella spiralis

Question 14

Describe the pathogenesis of STEC (Shiga-toxin-producing E. Coli).

Answer 14

• Adhesion to intestinal tract
• Colonization to intestinal tract
• Production of Shiga toxin.

Question 15

What are the dominant spoilage microorganisms in vacuum packed meat?

Answer 15

• LAB

- S. putrifaciens, Brochothrix thermosphacta, psychrotrophic enterobacteriaceae.

Question 16

How to prevent contamination in frozen meat?

Answer 16

• Thaw at refrigeration temperatures.
• Properly discard drip
• Cook to proper internal temperatures.
• Effective cleaning of tools and equipment.

Question 17

Ground meat is said to have a higher microbial number. What are the reasons?

Answer 17

• Redistribution of bacteria.

- Warm temperature.

Question 18

What contributes to the pink coloration of fermented sausage?

Answer 18

The reaction of nitrite with metmyoglobin to form nitric oxide myoglobin.

Question 19

What are the bacteria used to ferment sausages?

Answer 19

• LAB, micrococcaceae, coagulase-negative staphylococci.