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Chapter 3 : Microbial Ecology in Food Safety Risk Assessment
The health risks associated with food-and water-borne microbiological hazards are influenced by a complex interplay of variable factors. In this chapter, risk is assumed to relate directly to risk to human health, considering the probability and severity of illness both to individuals and the overall population exposed. The effect of microorganisms is related more to their number than their size, and microbiologists typically think in terms of populations of microbes. It might be expected that development of reliable microbial food safety risk assessments will require a sound understanding of the microbial ecology of foods and the ability to express that understanding mathematically. Microbial hazards in foods can be extremely sensitive to their surroundings and, under some conditions, the microbial ecology of foods has characteristics of a chaotic system. The microbial ecology of foods is deterministic and much is known that can be applied to microbial food safety risk assessment to increase the scientific credibility and utility of risk assessment outcomes. The chapter summarizes knowledge of the deterministic aspects of microbial ecology of foods that is relevant to the conduct of microbial food safety risk assessment; highlights sources of variability and uncertainty in microbial behavior; reviews approaches that have been adopted to model microbial growth, stasis, and death along the farm-to-fork pathway, and identifies sources of information that can assist microbial food safety risk assessors to produce models that are more scientifically rigorous and thus defensible. It discusses five main groups of microorganisms which include algae, fungi, protozoans, bacteria, and viruses.