Microbial Risk Assessment (MRA) is a systematic process comprising risk assessment, management, and communication, aimed at ensuring food safety by evaluating potential health impacts from microorganisms. Key components include hazard identification, exposure assessment, hazard characterization, and risk characterization, which together inform effective risk management strategies. International approaches, such as Good Manufacturing Practices (GMP) and the Hazard Analysis Critical Control Point (HACCP) system, play significant roles in minimizing microbial contamination and enhancing food safety standards.

1. Microbiological risk
assessment
Atia Ali

2. Contents
 Risk assessment
 Risk management
 Risk communication
 Challenges to microbial control of food
 International approaches to maintain food safety

3. What is MRA?
 Microbial risk assessment (MRA) is a tool that provides better means of
ensuring the production of safe food

4. Risk analysis
Risk analysis is a process comprising:
 Risk assessment – the scientific evaluation of known or potential adverse
health effects
 Risk management – evaluating, selecting and implementing policy alternatives
 Risk communication – exchange of information amongst all interested parties

5. Risk assessment
Risk assessment for microbiological hazards in foods is defined by the Codex
Alimentarius Commission (CAC) as a scientifically based process consisting of four
components:
• Hazard identification
• Exposure assessment
• Hazard characterization
• Risk characterization.

6. Hazard identification
Hazard identification is predominantly a qualitative process intended to identify
microorganisms or microbial toxins of concern in food or water. It can include
information on the hazard of concern as well as relevant related data, such as
clinical and surveillance data.

7. Exposure assessment
Exposure assessment should provide an estimate, with associated uncertainty, of
the occurrence and level of the pathogen in a specified portion of food at the
time of consumption, or in a specified volume of water using a production-to
consumption approach.

8. Hazard characterization
Hazard characterization provides a description of the adverse health effects that
may result from ingestion of a microorganism. When data are available, the
hazard characterization should present quantitative information in terms of a
dose response relationship and the probability of adverse out

9. Risk characterization
Risk characterization is the integration of the three previous steps to obtain a
risk estimate (i.e. an estimate of the likelihood and severity of the adverse
health effects that would occur in a given population, with associated
uncertainties

10. Risk assessment

11. Risk management
It is the process of deciding and implementing mitigation methods for the
appropriate level of safety. There is usually no “0” risk. Risk managements have
following elements:
 Risk evaluation
 Risk management option assessment
 Implementation of management decision
 Monitoring and review

12. Cont..
Risk evaluation
 Identification of a food safety problem.
 Establishment of a risk profile
 Ranking of the hazard for risk assessment and risk management priority.
 Establishment of risk assessment policy for conduct of risk assessment.
 Commissioning of risk assessment.
 Consideration of risk assessment result

13. Cont..
Risk management option assessment
 Identification of available management options
 Selection of preferred management option, including consideration of an
appropriate safety standard
 Final management decision
Monitoring and review
 Assessment of effectiveness of measures taken
 Review risk management and/or assessment as necessary.

14. Microbiological examination of food
 Microbiological testing of food is limited because the routine examination of
foods for a multiplicity of pathogens and toxins was impractical
 Enumeration of the organisms was performed and were termed as ‘indicator
organisms’ that reflect microbiological safety and quality of foods
 A criteria was set for every organism on the basis of their pathogenicity e.g.
Salmonella should be absent from food because very low numbers are known
to be capable of causing illness while Staphylococcus aureus, may be
acceptable at levels that are well below those causing food to become
hazardous
 The limitation of testing for pathogenic organisms that may be infrequent,
low in number and unevenly distributed throughout the test batch

15. Factors contributing to risk analysis
 Stability: Microbial contaminants may die-off or even multiply during storage
depending on the conditions.
 Behaviour: The storage behavior of microorganisms in foods is affected by
various intrinsic and extrinsic factors, and can vary considerably from food to
food and from one organism to another.
 Origin: Microorganisms occur naturally, especially in raw foods, and their
presence cannot be avoided.

16. Cont..
End-product criteria: Less useful for microorganisms due to changes in
microbial counts with time and the difficulty of detecting low number pathogens
Exposure assessment: The value of counts obtained for the purposes of
exposure assessment will depend upon the timing of the tests and the
subsequent storage history of the food.
Assessment of dose–response relationship: The necessary information for
microbial pathogens must be taken from feeding trials involving human
volunteers.

17. International approach for food safety
 Predictive modelling is a valuable tool, which has helped to make possible
the introduction of quantitative risk assessment (QRA)
 QRA has been used for many years in other disciplines and its use in food
microbiology has been stimulated by the decision of the World Trade
Organisation (WTO) to promote free trade in safe food
 Good manufacturing practice (GMP) concept which helps to minimize
microbial contamination of food from personnel and the production
environment. It provides standardize requirements for plant layout, hygienic
design of equipment and control of operational procedures.

18. HACCP
 In 1972, the hazard analysis critical control point (HACCP) system was
developed by Department of Health, Education and Welfare in which GMP
plays an important part.
 The HACCP concept is a systematic approach to the identification, assessment
and control of hazards in a particular food operation
 It aims to identify problems before they occur and establish measures for
their control at stages in production
 It has 7 principles and pre defined activity is documented for each principle

19. Principle Activity
Conduct a hazard analysis List all potential hazards associated
with each step, conduct a hazard
analysis, and consider any measures to
control identified hazards
Determine critical control points (CCPs) Determine CCPs
Establish critical limit(s) Establish critical limits for each CCP
Establish a system to monitor control
of the CCP
Establish a system to monitor control
of the CCP
Establish the corrective action Establish the corrective action to be
taken when monitoring indicates that
a particular CCP is not under control
Establish verification procedures Establish procedures for verification to
confirm that the HACCP system is
working effectively
Establish documentation and record
keeping
Establish documentation concerning
all procedures and records of these
principles and their application

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