Chapter 8 Controlling Microbiological Quality and Safety

Question 1

What are the purposes of environmental sampling?

Answer 1

• To monitor the efficacy of microbiological control

- To investigate the source of contamination.

Question 2

What are the two stages of biofilm formation? State two microorganisms that are able to form biofilms.

Answer 2

• First stage: The reversible attachment via van der Waals interaction
• Second stage: The irreversible attachment via the anchoring of appendages and/or the production of polysaccharides
• Pseudomonas, salmonella, listeria monocytogenes.

Question 3

What are the consequences of biofilm formation? How to prevent the formation of biofilm

Answer 3

• Microorganisms are protected from cleaner, sanitizer and heat
• Biofilm causes corrosion and operational problems.
• Prevented by cleaning, sanitation and hygiene programs; sanitarians check on the efficacy of cleanup operation.

Question 4

State the 4 principles of environmental pathogen control. Provide examples for each principle.

Answer 4

• Design of equipment and facilities: Avoid scratched surface, dead ends, crevices in equipments
• Separate raw from RTE foods: Physical barrier between ready to eat foods and raw foods.
• Good manufacturing practices: Proper personal hygiene, adequate cleaning of equipment and tools.
• Environmental monitoring: By end product testing and environmental monitoring.

Question 5

What are some techniques for environmental sampling?

Answer 5

• Sponge samples
• Swab samples
• Contact Plate
• Pre-sterilized tongue blades
• Air sampling
• ATP bioluminescence

Question 6

What are the two methods of air sampling?

Answer 6

• By using impingers or by passive air monitoring.

Question 7

Describe ATP bioluminescence, its advantages and its drawbacks.

Answer 7

ATP bioluminescence indicates the presence of microorganisms by detecting bacterial ATP. The use of luciferase and luciferin in the presence of ATP releases light.

• The advantage is the ease of implementation.
• The drawback is that bioluminescence sensors do not provide any information regarding the origin of ATP source.

Question 8

What are some methods of bacterial identification?

Answer 8

• Biochemical testing - Detect the presence of enzymes.
• Serological identification - The use of antiserum (solutions of antibodies) to identify bacteria of different strains
• Bacteriophage typing - Using bacteriophages to determine susceptible bacterium.
• Molecular methods - DNA amplification via PCR