Lecture 1: Introduction to pathogenic microorganisms and foods

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A.Food Safety and H.A.C.C.P.2.Pathogenic
microorganisms and foods
1. Introduction to pathogenic microorganisms and
foods
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Pathogenic microorganisms

• Microorganisms can cause diseases to humans
• Bacteria are the main pathogenic microorganisms
  that can be found in foods

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Elements of food microbiology

• Bacteria, yeasts and fungi main food
  microorganisms

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Limit the factors affecting the growth of
microorganisms

• temperature
• food humidity
• time
• acidity

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Bacteria and oxygen

• Oxygen requirements of bacteria
• a) bacteria that require oxygen to grow
  (aerobic)
• b) bacteria that do not require oxygen to grow
  (anaerobic)
• c) bacteria that can grow with or without oxygen
  (facultative anaerobic)

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Temperature requirements for bacterial growth

• a) psychrotrophic bacteria optimum temperature
  between 14-20 o C, usually grow at temperatures
  lt10 o C
• b) mesophilic bacteria optimum temperature
  between 30-37 o C, usually grow between 20-45 o C
  
• c) thermophilic bacteria optimum temperature
  between 50-60 o C, usually grow at temperatures gt
  45 o C

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Temperature, time and bacteria

• Temperature is closely related to time (cold
  chain) and it is the main factor affecting the
  growth of bacteria!
• How to maintain the cold chain
• be aware of the temperature of the product we
  receive
•  make sure that our refrigerators work properly
•  prevent temperature rise of the products

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Temperature zones and bacteria

• 5 to 60 0C danger zone
• 0 to 5 0C slow bacterial growth
• 6o 0C and microorganisms are killed
• -o 0C and inhibition of multiplication

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Growth rate of microorganisms
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Summary of 1st Lecture

• Pathogenic microorganisms
• Factors influencing the growth of microorganisms