Chapter 4 Canned Foods

Question 1

How can canned foods be classified based on acidity?

Answer 1

• Low acid, > pH 4.6
• Acid, pH 3.7 - pH 4.6
• High acid, < pH 3.7

Question 2

What is the D value?

Answer 2

The D value is the heating time in minutes needed to achieve a 1 log reduction in the number of cells of microorganisms.

Question 3

How can spoilage be detected in canned food?

Answer 3

• Swollen can due to gas formation

- Destructive analysis.

Question 4

What are the types of spoilage that can happen in canned food?

Answer 4

• Incipient Spoilage
• Post-process spoilage
• Inadequate thermal treatment
• Thermophilic spoilage (storage at high temperatures)

Question 5

Which bacteria is the primary concern in incipient spoilage? Why?

Answer 5

Staphylococcus aureus, S. aureus produce heat resistant toxins.

Question 6

What are the possible causes of post-process contamination?

Answer 6

• Defective containers
• Inadequately formed seams
• Leakage of cooling water into container
• Unsanitary equipment
• Rough handling of processed containers
• Presence of food in the container seam or seal.

Question 7

What are some factors that contribute to inadequate thermal processing?

Answer 7

• Thermal process not properly established and/or delivered
• Size and material of container
• Consistency of food
• Initial temperature of component.
• The nature of food (high fat require longer heating time)

Question 8

What are some ways to determine the cause of spoilage?

Answer 8

• Review of records
• Examine cooling water
• Examine for signs of leakage
• Destructive analysis
• Subculturing investigation.

Question 9

What are the types of spoilage microorganisms associated with canned foods?

Answer 9

• Mesophilic Aerobic Sporeformers
• Mesophilic Anaerobic Sporeformers
• Aciduric Flat sour sporeformers
• Thermophilic Flat sour sporeformers
• Thermophilic Anaerobic Sporeformers

Question 10

How to prevent thermophilic flat sour spoilage?

Answer 10

Cool thermally processed products to below 40-43oC and store them below 35oC

Question 11

What is the culprit of the sulfide stinker spoilage?

Answer 11

Desulfotomaculum nigrificans, it produces hydrogen sulfide and black discoloration.

Question 12

What bacteria causes thermophilic anaerobic spoilage? How to prevent thermophilic anaerobic spoilage?

Answer 12

Thermoanaerobacterium thermosaccharolyticum.

- Regular sanitation of equipment, examine food materials for spore levels.