Lecture 2: Biological hazards in foods

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A. Food Safety and H.A.C.C.P.5. Food Hazards
2. Biological Hazards in Foods
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Biological hazards (part I)

• they are biological agents that pose a threat to
  human health
• they are a major concern to food service managers
  and Health Inspectors because they cause most
  food borne illness outbreaks

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Biological hazards (part II)

• they include pathogenic bacteria (Coliforms,
  Clostridium botulinum, Clostridium perfrigens,
  Staphylococcus aureus, Listeria monocytogenes,
  Salmonella, Shigella, Bacillus cereus,
  Campylobacter jejuni, Yersinia enterocolitica)
  viruses (hepatitis A virus, Norwalk viruses,
  Rotavirus) and parasites (Toxoplasma gondii,
  Cryptosporidia, Giardia spp., Trichinella
  spiralis, Taenia solium, Anisakis spp.)
• most foodborne illnesses result from the
  consumption of microorganisms that contaminate
  food

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Biological hazards Risk in Foods

• These microorganisms can affect human health
  causing infections, intoxication or even death
• Infection occurs when microorganisms invade the
  host and multiply in the body
• Intoxication occurs when bacteria produce toxins
  that affect the body.  
• Infection can be prevented by properly processing
  and handling food products because pathogens are
  easily destroyed by heat
• However, some bacteria that produce spores can
  survive cooking temperatures

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Sources of biological contaminants 

• animal guts (fecal contamination)
• soil and water contaminated by non-treated manure
• cross contamination
• human contamination due to poor personal hygiene
  (skin, clothing, especially hands), fecal
  contamination (human guts), failure in infection
  control (illness not reported)
• Cross-contamination of food products spread from
  processing environment due to poor/improper
  sanitation  

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Sources of microbiological hazards
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Factors affecting the growth of microorganisms in
foods (part I)

• The temperature values for microbiological growth
  depend on the type of microorganism
• - psychrotrophs, such as Listeria monocytogenes,
  grow at refrigeration temperature (4C or 39F)
• - thermotrophs can grow at higher temperatures
  (45C or 113F).

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Factors affecting the growth of microorganisms in
foods (part II)

• The pH of products affects the growth of bacteria
• Most bacteria grow in a pH range between 5 and 9.
• Water Activity (Aw)  Higher Aw substances tend
  to support more microorganisms.

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Control of biological hazards

• effective thermal processing used as a kill step
  (ex cooking, pasteurization)
• use of appropriate process controls
• storage temperatures (eg cooler, freezer)
• processing parameters (eg temperature and time
  for cooking, water activity during dehydration)
• adequate cooling system
• effective cleaning and sanitizing procedures
• use of food technologies to prevent the growth of
  bacteria or other biological hazards
• packaging techniques (eg use of vacuum
  packaging, modified atmosphere packaging)
• preservatives
• processing techniques (eg dehydration)

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Control of microbiological hazards
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Prevent the multiplication of food poisoning
bacteria
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Groups at high risk for food poisoning
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Summary of 2nd Lecture

• Biological hazards in foods
• Sources of biological hazards
• Control of biological hazards