Summer Webinar Series: Food Microbiology 101

Presenter: Thomas Jones, Senior Director of Analytical Services, Safe Food Alliance

Introduction

• Welcome to the summer webinar series on food microbiology and environmental monitoring.
• Focus: Understanding microorganisms in food safety.

What are Microorganisms?

• Microscopic living creatures not visible to the naked eye.
• Example: 13,000 E. coli cells make up an inch.
• Five basic categories:
  • Bacteria
  • Yeasts
  • Molds
  • Viruses
  • Protozoa

Microbes of Importance in Foods

Bacteria

• Properties:
  • Grow as single cells, can produce heat-resistant endospores.
  • Prefer moderate moisture and pH conditions.
  • Pathogens such as Salmonella, toxigenic E. coli, and Listeria monocytogenes.

Key Pathogens

• Salmonella:
  • Over 2500 strains, reservoirs in humans and animals.
  • Associated with outbreaks in fresh produce and low moisture foods.
• Toxigenic E. coli:
  • Causes serious foodborne illnesses.
  • Linked to meats, juices, milk, nuts, flour, and leafy greens.
• Listeria monocytogenes:
  • Grows under refrigeration, high salt tolerance.
  • Common in soil, linked to produce like melons and deli meats.

Yeasts and Molds

• Yeasts:
  • Single cells, acid-tolerant, grow in high sugar foods.
  • Beneficial in products like beer and bread, can also cause spoilage.
• Molds:
  • Grow as filaments, produce resistant spores.
  • Tolerant to extreme conditions, major source of spoilage.
  • Produce toxic chemicals like aflatoxin.

Viruses and Protozoa

• Viruses:
  • Do not grow in food, cause illnesses like hepatitis A.
  • Transmitted by food handlers, minuscule infectious doses.
• Protozoa:
  • Single-celled parasites, cause disease via fecal contamination.
  • Resistant to sanitizers, outbreaks in water systems.

Controlling Microorganisms in Food

• Modify factors like nutrients, acidity, temperature, time, oxygen, and moisture (FAT TOM).
• Acidity (pH):
  • Low pH inhibits microbial growth.
• Temperature:
  • Mesophiles thrive in moderate temperatures.
  • Cooking kills microbes; refrigeration slows growth.
• Time:
  • Limit time food is at optimal growth conditions.
• Oxygen:
  • Aerobes require oxygen; anaerobes thrive without it.
• Moisture:
  • Measure via water activity; lower activity inhibits growth.

Sanitation and Environmental Monitoring

• Facility Entry Points:
  • Personnel, raw materials, pests.
• Control Measures:
  • Proper handling, hygiene, equipment maintenance.
  • Ongoing cleaning and sanitation, pest control.
• Environmental Monitoring:
  • Early warning system for sanitation effectiveness.
  • Compliance with FSMA, identification of pathogens like Salmonella and Listeria.

Sampling and Zoning

• Conduct risk assessments, select sampling sites.
• Zoning:
  • Zone 1: Product contact.
  • Zone 2-4: Varying distances from contact.
• Sampling Protocols:
  • Use swabs, dust samples, water/air tests.
  • Increase frequency in higher-risk zones.
• Response to Positives:
  • Immediate corrective actions, increase sampling frequency.

Conclusion

• Environmental monitoring as an essential verification tool.
• Protects consumer safety, ensures regulatory compliance.
• Keeps track of sanitation effectiveness, identifies potential hazards early.