Chapter 3 Vegetables and Fruits

Question 1

What are the origins of contamination of fresh produces?

Answer 1

• Environment
• Structural entity of the plant
• Insects
• Agricultural practices

Question 2

What is the main mechanism that provides defense against microorganism in plants?

Answer 2

Waxy cuticle.

Question 3

What causes the internalization of pathogens in produce?

Answer 3

• Water repelling waxes.
• Uptake through cracks and crevices
• Biofilm formation on leaves and roots
• Bacterial infiltration.

Question 4

Provide 2 example of soft-rot bacteria.

Answer 4

• Erwinia spp.
• Pseudomonas spp.
• Bacillus spp,

Question 5

What are some examples (5) of good agricultural practices?

Answer 5

• Proper irrigation using suitable water sources.
• Education of field workers.
• Excluding ill workers.
• Adequate hand-washing facilities.
• Pest management
• Proper garbage management.
• Sanitation and inspection of equipment and surfaces.

Question 6

Why do fresh cuts perish at higher rates?

Answer 6

• Fresh cut is wounded tissue, which respires at a higher rate and is less permissive of temperature abuse.

Question 7

What are the adaptations that bacteria can make to grow in plants and foods?

Answer 7

Acid tolerance response (ATR), e.g. in acid tolerant Salmonella.

Question 8

List the common spoilage microorganisms (4) in vegetables and fruits.

Answer 8

• Fungi
• Listeria monocytogenes
• Shigella sp.
• Cl. botulinum
• Hepatitis A
• Bacillus cereus
• Cl. perfringens

Question 9

Describe the 3 phase of sauerkraut fermentation.

Answer 9

Phase I: Leuconostoc mesenteroids initiates fermentation, produces lactic acid, acetic acid, and CO2
Phase II: Lb. breveris and Lb. plantarum increase in numbers
Phase II: Lb. plantarum dominates the microflora and continue fermentation.

Question 10

What are the causes of spoilage in sauerkraut?

Answer 10

• Aerobic conditions
• Uneven salt distribution
• Insufficient acid

Question 11

What are some ways to control microbial growth in dried fruit?

Answer 11

• Reduction in fruit damage
• Sanitary condition
• Moisture control.

Question 12

Why is aeration important in grain production?

Answer 12

Aeration reduces moisture, temperature and avoid convection currents and condensation.

Question 13

What are the ways to controlling spoilage for produce and fruits?

Answer 13

• Washer: Immersion and non-immersion washer
• Chemical decontamination: Using 200ppm chlorine.
• Physical decontamination: Using 65C hot water (in water melon).

Question 14

What are the factors affecting efficiency of immersion and non immersion washers?

Answer 14

• Time of contamination
• Load of contaminants
• Water quality
• Use of surfactants and antimicrobials
• Internalization.

Question 15

What are the limitations of chemical decontamination using chlorine?

Answer 15

• Inaccessibility within tissue
• Neutralization by tissue components.
• Efficiency affected by surface properties.