Saturday, 10 December 2011


Hazard to food safety

Foodborne hazard
  •  biological - bacteria, viruses, parasite
  • chemical - toxic substances that may occur naturally (during food processing)
  •  physical - any foreign object in food that can cause illness and injury (hair, nail, staple)
Bacteria
    •  aerobic - need oxygen to grow
    • anaerobic - cannot survive when oxygen presence and  all bacteria can grow, reproduce, and produce waste

1.       spore forming bac
§  able to form, help bac survive when the environment to hot cold, dry, or acidic or when not enough food
§  temp. danger zone and more than 4 hour (5˚c - 60˚c)
§  harder to destroy
§  exp: bacillus cereus, closlidium perfringens

2.       non-spore forming
§  not capable to form spores, easy destroy by cooking and cooling
§  exp: escherichia coli, salmonella

3.       viruses
§  smaller that bac
§  need living host to multiply
§  exp: hepatitis  A, Norwalk virus- JE, bird flu

4.       parasites
§  small or microscopic creatures- live in or on another from whose body it obtains nourishment
§  exp: anisakis SPP, trichinella spireliss (in pork)

5.       spoilage and disease ( causing bac)
§  it will degrade food.
§  look, taste, and smell bad -  reduce quality of food

6.       pathogenic bac
§  disease causing microorganisme that can make people ill if their toxins are consumed with food

several type of bac:
  •  psychrophilic
Ø  bac. grow 32˚F to 70˚F (0˚C to 43˚C)
Ø  become capable to multiply in both refrigerated and room temp
Ø  most are spoilage bac but some can cause disease

  •  mesophile
Ø  bac. grow 70˚F to 110˚F (21˚C- 43˚C)
Ø  most rapid growth in human body (37˚C)

  •  thermophile
Ø  bac that grow best at above 43˚C
Ø  time and temperature - critical factor affecting bac growth
Ø  careful time and temp to avoid temp abuse
Ø  bac need 4 hours to grow to high enough number to caused illness

6 conditions bac growth (FATTOM) 
  •   Food - high in protein, carbohydrate
  •  Acid       - pH greater than 4.6
  •  temperature - dangerous zone (5˚C to 60˚C)
                           - super danger zone (21˚C to 49˚C)               


  • time - 4 hours cumulative time to allow bac to grow to high enough number to cause illness

  • oxygen - aerobic 
    • anaerobic
    • facultative anaerobic
    • multi aerophilic
  • moisture - water activity greater tan 0.85-lw



4 phase of bac growth:


  1. lag phase - bac exhibit little/ no growth, last only a few hours at room temperature
  2. log phase  - bac. grow rapidly. some can double in number every 20 to 30 minutes
  3. stationary phase - the number of new bac. being produced equal the number of microorganism that are drying off. Bac. have used up most of the space, nutrients and moisture.
  4. decline stage - bac. die off rapidly bcos of lack nutrient or poisoned by their own waste.



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