Food Protection Trends - May/June 2020 - 205

Microbiological testing can also be used by the manufacturer
to demonstrate that a particular preventive control is being
implemented effectively and consistently on an ongoing basis.
Different types of preventive controls (and related FSMA
requirements) can be verified by microbiological testing.
Microbiological testing can provide evidence that an antimicrobial process such as high-pressure processing has been
correctly performed (a process preventive control). It is also
important for allowing customers (food manufacturers or
retail buyers) to know that the ingredient or finished product
they are purchasing meets certain specifications that fulfill
their supply chain preventive controls and verification requirements. It is also critical for verifying sanitation controls
and useful for showing that current Good Manufacturing
Practices have been achieved.
A key but subtle distinction between "testing to verify that
a preventive control is working" versus "testing to establish
lot acceptability" lies in the rationale for the microbiological
testing. Are you testing to ensure that your systems to control
microbiological hazards are working correctly, or to ensure that
there are no pathogens present in a small, presumably representative, sample of the final product? Because this distinction
is often missed, considerable confusion exists among food
manufacturers and others. To help clarify these issues for food

manufacturers and regulators, Scott presented a preliminary
list of basic principles to help guide the use of microbiological testing when manufacturing an RTE food (Fig. 2). Guided
by these draft principles, Scott also discussed draft criteria
that RTE food manufacturers can use to help them decide
whether, or how often, they should perform microbiological
testing (Fig. 3).
Jenny Scott described how these preliminary principles
and criteria could be used by food manufacturers to design
microbiological testing strategies for different types of RTE
foods. Some of these principles were used in the group exercise
discussed later. When faced with the final question as to
whether or not a firm should test finished products, Scott said,
"It depends." Microbiological testing may be necessary at the
ingredient stage or for the end product (where such testing
can demonstrate the successful application of controls). There
is not always a right or a wrong answer, as different facilities
making the same product may come up with different answers
about whether or not to test (and both could be correct).
Verification vs. validation, one more time
Robert Buchanan reviewed the regulatory definition of verification found in the preventive controls for human foods rule
that pertains directly to microbiological testing (Fig. 4).

1. Microbiological testing should be risk-based.
2. Microbiological testing for verification of process control is different from microbiological testing for lot acceptance.
3. Microbiological testing is most useful when
* ingredients in a food have the potential to contain pathogens and there is no (or a marginal) kill step in the
manufacture of the finished product, and/or
* finished products have the potential to be contaminated from the environment.
4. Microbiological testing should be increased when information indicates that the operation is not under control.
5. A facility should consider the nature and extent of supplier control programs for ingredients and environmental
monitoring programs in the facility in determining the role of finished product testing to verify control measures in
the facility.
6. Sampling small amounts of product more frequently provides better information about process control than taking a
larger sample equivalent in weight to the sum of the weight of the smaller samples.
Figure 2. Suggested principles for determining the need for microbiological testing when manufacturing RTE foods.

* Have pathogens been associated with the food or its ingredients? Has the food been associated with illnesses?
* Are the ingredients likely to be contaminated?
* Are there robust processing control procedures such as a kill step or other reduction methods/controls? If so, is the reduction
a result of the formulation or the application of a process control measure, and what is the magnitude of the reduction?
* Is there a potential for recontamination from handling or the environment?
* Does the product support survival or growth of pathogens?
* What is the shelf life of the product?
* Is this product meant specifically for a higher risk population?
* Is consumer handling and use likely to increase or decrease risk?
Figure 3. Suggested questions for decisions on performing microbiological testing when manufacturing RTE foods.

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Food Protection Trends - May/June 2020

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