Industry Information Session: Implementation of the 2011 Health Canada "Policy on Listeria monocytogenes in Ready-to-Eat Foods"
Summary of Questions and Answers

Note: the "Policy on Listeria monocytogenes in Ready-to-Eat Foods" is referred to as the "Listeria policy" in this document.

Questions and answers have been reviewed by the Canadian Food Inspection Agency Food Safety Science Directorate, Fresh Fruit and Vegetable Program and Processed Products Program, in consultation with Health Canada (2013).

Fresh and Processed Produce Subject to the Listeria Policy

Why are ready-to-eat retail prepared foods exempt from the Listeria policy?

The scope of the Listeria policy is to provide guidance to ready-to-eat (RTE) food processors on how to address Listeria in the environment of processing establishments and therefore does not address the foodservice or retail establishments. Foods prepared at retail are under provincial/territorial jurisdiction. One of the roles of provincial/territorial governments is to oversee the retail sector to ensure that it meets its food safety responsibilities. If RTE retail prepared foods are tested and an organism of concern is detected, a Health Risk Assessment (to be conducted by the Bureau of Microbial Hazards (BMH), Food Directorate, Health Products and Food Branch (HPFB), Health Canada) may be requested.

Why are frozen fruits (e.g., frozen berries) included in the Listeria policy while whole fresh fruits (e.g., fresh berries) are excluded?

The basis for frozen fruits being included is that, unlike fresh fruits, they undergo processing during which potential Listeria contamination can occur.

The Listeria policy states that the health risk changes if the product is used by a high risk population; please explain.

High risk populations include pregnant women, elderly and/or immunocompromised individuals (e.g., AIDS patients, transplant recipients, cancer patients, etc.).

RTE foods that are produced for consumption by individuals, who are known to be in the high-risk population, may be considered to represent a Health Risk 1 concern, if contaminated by Listeria monocytogenes, irrespective of the Listeria policy product Category. As per Table 1 of the Listeria policy, the presence of Listeria monocytogenes in a Category 1 RTE food would trigger a Health Risk 1 concern and counts of Listeria monocytogenes > 100 CFU/g in a Category 2 RTE food would trigger a Health Risk 2 concern. However, for Category 2 RTE foods intended for a high risk population, if counts are > 100 CFU/g, the product(s) would automatically be considered a Health Risk 1 situation. If counts ≤ 100 CFU/g are detected in such products (i.e., Category 2 RTE food produced for a high risk population), a Health Risk Assessment (to be conducted by the Bureau of Microbial Hazards (BMH), Food Directorate, Health Products and Food Branch (HPFB), Health Canada) may be requested which may also lead to a Health Risk 1 concern.

Would providing specific cooking instructions on the consumer package of fresh-cut fruit and vegetables products (e.g., fresh-cut mushrooms, vegetable kebobs for BBQ) be sufficient to exclude these products from the Listeria policy?

Product labelling cannot be used as the sole criterion to determine inclusion or exclusion from the Listeria policy. For example, fresh-cut mushrooms bearing cooking instructions would still be included in the scope of the Listeria policy. The Listeria policy contains the criteria for determining whether a product is included in the policy, irrespective of the labelling claim found on a product.

Scenario - What Category would frozen meals (containing vegetable components) fall into?

RTE frozen meals containing vegetables would fall under Category 2B as these foods do not support the growth of Listeria monocytogenes since they are frozen until consumption. However, if a frozen Category 2B product were to be temperature-abused causing it to thaw, or was sold refrigerated instead of frozen, growth of Listeria monocytogenes could potentially occur. A finding of Listeria monocytogenes in these products would lead to follow-up action(s) and a Health Risk Assessment. In these situations, Category 2 foods may be assessed to represent a Health Risk 1 concern.

Scenario - What Category would pre-cooked refrigerated or frozen mixed vegetable soup fall into?

Pre-cooked frozen mixed vegetable soups would fall under Category 2B since these foods do not support the growth of Listeria monocytogenes because they are frozen until their preparation for consumption. However, these products could be assessed to represent a Health Risk 1 situation (under the circumstances described in Question 6a).

Pre-cooked refrigerated mixed vegetable soups would fall under Category 1, unless the physico-chemical parameters of the products are such that the growth of Listeria monocytogenes will not occur (i.e., pH < 4.4 regardless of aw, aw < 0.92 regardless of pH, combinations of factors pH < 5.0 and aw < 0.94), in which case they would fall under Category 2B. For these products, food processors would need to monitor and maintain records of physico-chemical parameters such as pH and aw, demonstrating that they continue to meet the criteria that justify their classification in this category. If information is insufficient, inadequate or no information exists to demonstrate that there is no potential growth of Listeria monocytogenes throughout the shelf-life, the food will be treated by default as a RTE food in which growth of Listeria monocytogenes can occur i.e., Category 1 RTE food.

Would the following (washed or unwashed) products be included in the Listeria policy: sprouted seeds/bean sprouts, micro greens, leafy greens and whole mushrooms?

Any types of sprouts, micro greens, leafy greens or whole mushrooms are considered as whole raw fresh fruit and vegetables, i.e., whole fresh fruit and vegetables that have only been trimmed, cleaned, brushed, washed, graded, packaged or similarly handled. According to the Listeria policy, whole fresh fruit and vegetables are not subject to the provision of this policy.

If a product is labelled as non RTE, does this exempt it from the Listeria policy?

Product labelling cannot be used as the sole criterion to determine inclusion or exclusion from the Listeria policy. The Listeria policy contains the criteria for determining whether a product is included in the policy, irrespective of the labelling claim found on a product.

Ready-to-Eat Food Categories

Scenario - If a company has a regular monitoring program for Listeria monocytogenes end-product sampling and can demonstrate that there is no Listeria monocytogenes, can this information impact the category of the products (e.g., lower the Category from 1 to 2A)?

The categorisation of a RTE food is based on the growth potential of Listeria monocytogenes in the product: Good Manufacturing Practices (GMPs) or Hazard Analysis Critical Control Point (HACCP) are means to have effective control measures in place to limit or eliminate the incidence of Listeria contamination in a facility and in a food product. Industry interested to proceed with the re-categorisation of a RTE food will have to provide scientific evidence (validated data), to be reviewed and confirmed by regulatory authorities. They should follow Health Canada's guidance document "Validation of Ready-to-Eat Foods for Changing the Classification of a Category 1 into a Category 2A or 2B Food – in relation to Health Canada's Policy on Listeria monocytogenes in Ready-to-Eat Foods (2011)."

Would other types of treatments be considered a 'kill step' other than thermal treatment (e.g., sanitation, washing of fresh produce)?

A kill step refers to any validated treatment that achieves a minimum of 5 log reduction in number of Listeria monocytogenes. Thermal treatment is an example of a kill step that could achieve this log reduction, based on specific time and temperature. Washing treatments applied on fresh fruit and vegetables are not considered to be a kill step, unless it is proven it achieves a 5 log reduction during the treatment.

Physico-chemical parameters (pH and aw)

How many pH readings should be taken per lot per year, to ensure the product consistently meets < 4.4 and is therefore considered a Category 2B?

Physico-chemical parameters that would not permit the growth of Listeria monocytogenes are defined in the Listeria policy as being in the following range: pH < 4.4 regardless of aw, aw < 0.92 regardless of pH, combinations of factors pH < 5.0 and aw < 0.94. Hence, a ready-to-eat (RTE) food consistently having values within the ranges specified above would be considered as a Category 2B food.

The Listeria policy does not prescribe a specific frequency. The frequency depends on different parameters such as the nature of the product, production process and volume produced. For instance, if the pH is close to the 4.4 limit and/or requires addition of acidulants to achieve a pH below 4.4, frequent checks are likely necessary and potentially every lot, if pH has been defined as a Critical Control Point (CCP). Where pH is achieved through processing, ruggedness studies on the processing methods should be performed to determine which variables may have an impact on the pH of the final product. Therefore if a variable is deemed to have a high impact on the pH of the final product there should be measures in place to ensure this parameter is controlled. However, if the pH of the food is naturally low i.e., its pH is significantly lower than 4.4 and there is no need to control the pH through processing (e.g., a naturally acidic fruit),) then the frequency of pH checks can be lowered/reduced. It is the responsibility of the operator to develop a process, a monitoring and/or verification sampling plan that ensures all applicable product lots have a pH < 4.4.

How should the pH be taken for a fruit salad (e.g., a pH reading for each different type of fruit once they are mixed together, each different type of fruit prior to mixing, and/or the mixture of all fruits together)?

The pH for each of the different fruit components in the salad should be assessed and the overall categorisation of the fruit salad product would be based on the highest pH fruit in the final product. However if a slurry of all mixed fruits was done and this pH measurement was shown to be equal to or above 4.4, it can be immediately determined that the fruit salad is not a Category 2B food (unless validation studies are provided by the company to support that the growth of Listeria monocytogenes cannot occur and those validation studies are confirmed by regulatory authorities). If pH measurement for the mixed fruit slurry was less than 4.4 (pH < 4.4), categorisation of the product cannot be made and would be considered incomplete. Additional pH measurements would be required to confirm that each separate fresh-cut fruit component has a pH < 4.4. In fact, for a Category 2B determination (without validation studies), the critical pH parameters (i.e., pH < 4.4), must be shown to be achieved throughout the entire fruit salad. Health Canada recommends the use of the method MFHPB-03 for the determination of pH of foods available from Health Canada's Compendium of analytical methods (Volume 2).

If the product consistently shows a pH of < 4.4, does industry need to provide evidence (e.g., data, records) of the pH values?

Operators should record all pH measurements they perform on their products to provide evidence that the pH criterion for Category 2B products is met. In the absence of evidence, the product may be treated as a Category 1 food by default.

Methods of Analysis

Where can Listeria monocytogenes strains be obtained?

Strains can be purchased from a commercial culture supplier or organisation.

Is there a Listeria monocytogenes indicator organism?

Listeria spp. are considered indicator organisms for Listeria monocytogenes for food contact surfaces and non-food contact surfaces in a food industry environment. The presence of abnormally high levels of other groups of environmental organisms (e.g., Aerobic Colony Count (ACC), coliforms) on surfaces post-sanitation may also be an indication of sanitation issues, and potential presence of Listeria monocytogenes.

Is MFHPB-29 approved by Health Canada and/or the Canadian Food Inspection Agency to address environmental sampling?

This method is applicable to the rapid detection of Listeria spp. and may be used for environmental samples.

Note however that the confirmation section of MFHPB-29 states the following:

Note: If the results indicate that Listeria spp. have not been detected, it is understood that the presence of Listeria monocytogenes has also not been detected, since no species belonging to the Listeria genus were detected. However, if Listeria spp. are detected, regardless of the amount of colony screening or additional confirmation steps done, these results cannot be used to state that Listeria monocytogenes is absent. Report all species of Listeria that are identified.

When analyzing laboratory results, what is the difference between presence/absence vs. 100 CFU/g?

Presence/absence methods are more sensitive than enumeration methods. Presence/absence is a qualitative result, by which as little as 1 to 5 CFU of Listeria monocytogenes can be detected in the entire sample (for instance, as little as 1 to 5 CFU in the entire 125g sample size), and the test result will be reported as being positive for the presence of Listeria monocytogenes.

The enumeration method reports the actual counts of Listeria monocytogenes per gram of food sample (for instance a level of 100 CFU/g), which is a quantitative result. The enumeration method MFLP-74 can detect Listeria monocytogenes if present at levels equal to or greater than 5 CFU per gram of sample (based on a product/diluent ratio of 1 in 5).

Since the detection limit in a qualitative test is much lower than for a quantitative test, it is possible that a product would test positive in presence/absence of Listeria monocytogenes but would not be detected by the enumeration test.

Can industry use non-accredited laboratories to test for Listeria spp. on food contact and non-food contact surfaces or Listeria monocytogenes in RTE foods?

It is not mandatory to use accredited laboratories but industry is encouraged to select testing labs that have received formal recognition for the required testing from a recognized accreditation body such as the Standard Council of Canada (SCC) or the Canadian Association of Laboratory Accreditation (CALA). According to the Listeria policy, analysis of "food contact surfaces/non-food contact surfaces/end products" for the presence of Listeria spp. or Listeria monocytogenes should be conducted using any method published in Health Canada's Compendium of Analytical Methods for Listeria spp. or Listeria monocytogenes in which the "Application" section is appropriate for the intended purpose (e.g., MFHPB methods and MFLP methods). To find an accredited laboratory and view their scope of accreditation, go to: SCC or to CALA webpages.

Is the log reduction referred to in the Listeria policy meant for Listeria alone or for total plate count?

The log reduction mentioned all through the Listeria policy is always specific to Listeria monocytogenes.

Validation of Ready-to-Eat Foods for Re-Categorisation

When a validation study is conducted, can the same data be used for a similar product? For example, if a validation study was conducted on fresh-cut romaine lettuce, can this data be used for another type of fresh-cut lettuce or if the fresh-cut romaine lettuce is a component of a mixture?

It is understood that it might not be practical to conduct laboratory challenge studies for each product being manufactured by one processor; it could potentially be acceptable to group comparable products. The highest risk product for Listeria monocytogenes growth, within the group, should be used to perform the laboratory challenge study. A rationale, supported by scientific evidence needs to be provided to justify the grouping of products as well as for the selection of the highest risk product. For more information, refer to question 9 of the Summary of Comments Received on Health Canada's Proposed Document Validation of Ready-to-Eat Foods for Changing the Classification of a Category 1 into a Category 2A or 2B Food – in relation to Health Canada's Policy on Listeria monocytogenes in Ready-to-Eat Foods (2011).

Under what conditions would a product need to be re-validated. Does the validation data for changing a product's categorisation from a Category 1 to a 2A or 2B remain valid indefinitely?

If a change is intended or is made to a control measure or in a product or process-related factor that is likely to affect the effectiveness of the control measure (for example, process control, process parameters, etc.), the appropriateness of the validation studies supporting the categorisation of the product under consideration may need to be confirmed. If the change is determined by the relevant regulatory authority to be substantial, the need for re-validation/re-categorisation may be triggered. If no changes are made, and if on-going monitoring and verification procedures demonstrate that the food safety outcome is maintained, then the classification remains valid.

Industry Monitoring

What is the recommended frequency and minimum number of swabs for routine environmental swabbing?

According to the Listeria policy, under section 7.2 and footnotes a & b of Figures 1, 2 & 3, the number of meaningful sites will vary according to the complexity of the processing system of a plant:

The frequency and points of sampling for routine sampling should be plant and/or line specific, based on the manufacturing processes and the controls that are present (Tompkin et al., 1992). An increase in sample sites (FCSs and non-FCSs) and frequency should be considered during and/or after special circumstances (e.g., construction, the installation of used or modified equipment, overhead/ceiling leaks in exposed product areas), which may provide an opportunity for control of L. monocytogenes to be lost.

Environmental sample collection should be conducted according to method MFLP-41, published in Health Canada's Compendium of analytical methods (Volume 3).

Please refer to section 7.2 in the Listeria policy for further guidance on environmental swabbing.

Should industry test for Listeria monocytogenes or Listeria spp. on end-product samples?

Industry should test for Listeria monocytogenes in finished product samples because finished product compliance criteria, as indicated in Table 1 of the Listeria policy, is based on Listeria monocytogenes.

Should industry test products for Listeria monocytogenes that do not fall under the Listeria policy?

In general, it is not recommended that companies test for Listeria monocytogenes in products that do not fall under the policy. However, some products outside the policy may pose a risk if contaminated with Listeria monocytogenes, and therefore companies may choose to test these products for Listeria monocytogenes, as applicable. In general, it is recommended that food companies adhere to Good Manufacturing Practices (GMPs) or have a Hazard Analysis Critical Control Point (HACCP) system in place to prevent contamination in their facility and in their food products.

If products that do not fall under the policy are tested by industry and Listeria monocytogenes is found, what is industry's responsibility?

In such situations, the industry must inform the regulatory authority immediately. A risk assessment will then be conducted to determine appropriate product action.

What does the term 'persistent contamination' mean?

According to the Listeria policy, under section 7.2:

If two or more samples from the same production line (i.e., using the same equipment) are found positive within a short timeframe, this is considered to be evidence of persistent contamination and an indication that the Listeria control program could be inadequate.

CFIA Oversight and Verification

During CFIA oversight, are storage/warehousing of imported products part of CFIA verification inspections?

All aspects of importer's Good Hygiene Practices (GHP)/GMP or HACCP system could be assessed to verify effective control over potential Listeria contamination, including safe food storage or general warehousing practices at the importer's facility. Moreover, importers should always have in their possession imported product information such as supplier, processor or exporter.

Does CFIA have the authority to implement the Listeria policy in non-federally registered facilities?

Under the Listeria policy, CFIA's role and responsibilities are to oversee the food industry and the effectiveness of its Listeria control program, to ensure that food manufacturers and importers of RTE products meet their food safety responsibilities and comply with all applicable legislative and regulatory requirements, whether they are federally registered or not. Oversight may include taking environmental and/or product samples, reviewing industry's sampling and/or corrective action plans, verifying that corrective actions have been implemented, taking enforcement action, etc.

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