1. MICROBIAL FOOD SAFETY A FOOD SYSTEMS APPROACH
Charlene Wolf-Hall and William Nganje

2. Chapter 3: Intrinsic and Extrinsic Factors and Potentially Hazardous Foods

3. Key Questions
What are intrinsic factors of food that affect microorganisms? What are extrinsic factors of food that affect microorganisms? What is the temperature danger zone? What is a potentially hazardous food?

4. Environmental Factors
Intrinsic Factors - Environmental factors inherent, or internal to a food. Extrinsic Factors - Environmental factors external to a food.

5. Intrinsic Factors
Moisture Content and Water Activity pH and Acidity Nutrient Content Redox Potential Antimicrobial Chemicals Competitive Microflora Biological Structure Homogeneity

6. Extrinsic Factors Packaging and Atmosphere Time Temperature
Relative Humidity

7. Potentially Hazardous Foods
Foods for which the intrinsic and extrinsic factors would support the growth of pathogenic microorganisms. “Scientifically sound criteria for determining whether foods require time/temperature control for safety should consider 1) processes that destroy vegetative cells but not spores (when product formulation is capable of inhibiting spore germination); 2) post-process handling and packaging conditions that prevent reintroduction of vegetative pathogens onto or into the product before packaging; and 3) the use of packaging materials that while they do not provide a hermetic seal, do prevent reintroduction of vegetative pathogens into the product.” (IFT, 2001)

8. THANK YOU Name: Charlene Wolf-Hall & William Nganje
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