Industry Information Session: Implementation of the 2011 Health Canada "Policy on Listeria monocytogenes in Ready-to-Eat Foods"
Topic 7: Validation of RTE Foods for Re-categorization

For more information, refer to HC's document, Validation of Ready-to-Eat Foods for Changing the Classification of a Category 1 into a Category 2A or 2B Food.

Validation – Definition

(Section 2 of HC's Validation Document)

Codex Alimentarius Commission (2008) defines validation as:

"Obtaining evidence that a control measure or combination of control measures, if properly implemented, is capable of controlling the hazard to a specified outcome."

Validation of RTE Foods for Re-Categorization – Purpose

(Section 1 of HC's Validation Document)

  • Demonstrate using scientific evidence that a RTE food product, covered by HC's Listeria Policy, is Category 2 (2A or 2B)
  • The product is considered to be Category 1, if insufficient, inadequate or no information exists to demonstrate a 2A or 2B categorization or if the categorization has not been confirmed by regulatory authorities (e.g., CFIA)

Pre Validation

(Section 3.1 and 4.1 of HC's Validation Document)

a) Hazard identification:

  • Presence of unacceptable levels of Lm in RTE foods as per HC's Listeria Policy (i.e., > 100 CFU/g of Lm at any time throughout the stated shelf-life)

b) Identification of food safety outcome:

  • Category 2A RTE Food: Lm, when present, should be limited to a maximum of 100 CFU/g throughout the stated shelf-life
  • Category 2B RTE Food: Growth of Lm will be less than a 0.5 log CFU/g increase throughout the stated shelf-life of the RTE product

c) Identification of the measure(s) that need to be validated:

  • Challenge studies need to demonstrate when RTE foods are processed according to specified parameters, the desired food safety outcome is achieved

Validation of RTE Foods for Re-Categorization

(Section 2 of HC's Validation Document)

  • Challenge Studies – Mandatory
  • Identification of Key Process Parameters, and Provisions of Evidence of their Control – Mandatory
  • Literature Review – Recommended
  • Modelling – Optional

Validation of RTE Foods for Re-Categorization

(Section 3.2 and 4.2 (b) of HC's Validation Document)

Challenge Studies – Mandatory

  • To determine the ability of the product to support limited or inhibit the survival and growth of Lm throughout the duration of the stated shelf-life
  • Results must demonstrate that the food safety outcome is met

Challenge studies should be conducted as per HC's, Lm Challenge Testing of Ready-to-Eat Refrigerated Foods.

Validation of RTE Foods for Re-Categorization

(Section 3.2 and 4.2 (b) of HC's Validation Document)

Challenge Studies – Recommended Experimental Design

Lm strains

  • Use a pool of at least 3-5 strains (can be up to 10)
  • Certain serotypes should be included (1/2a, 1/2b and 4b)
  • Include strains isolated from the same, or similar types of food
  • If available, use an outbreak strain, or sporadic cases
  • Cultures are available from international culture collections (e.g., ATCC and ILSI)

Preparation and enumeration of cells

  • Consult with an expert food microbiologist
  • Storage of cells should minimize the number of transfers to minimize mutations
  • HC's Challenge Study document provides guidance to:
    • Avoid multiple passages
    • Incubate cells at refrigeration temperatures since the RTE foods will be refrigerated
    • Enumerate cells of a working inoculum

Inoculum level

  • Inoculation level used should be10-30 CFU/g to attempt Category 2A classification
  • Inoculation level to demonstrate Category 2B classification has not been pre-set by regulatory authorities. The initial level of inoculum can vary, so long as, for example, it does not overload the preservative system/natural hurdles associated with the product and that the concentrations can be easily enumerated. Examples of level of inoculation are presented in Table 1 of HC's, Lm Challenge Testing of RTE Foods.

Sampling design

  • Minimum of 3 lots of products must be tested for Lm in triplicate at each sampling time (i.e., a minimum of 5* time points throughout the stated shelf-life, including time zero and at the end of the shelf-life).

    *If the product has an extended refrigerated shelf-life, additional time points throughout the stated shelf-life of the product should be considered, in order to account for possible variations in the growth of Lm.

Preparation of food product

  • Need to know the critical parameter and process variability of the product
  • Use "worse-case" conditions (i.e., most permissive for growth of Lm)
  • Consider competing background microorganisms

Inoculation of food product

  • Inoculation method should reflect the way contamination is likely to occur and the condition of the product at that point
  • Examples of inoculation methods are available in HC's, Lm Challenge Testing of RTE Foods

Special product packaging conditions

  • Inoculated product should be packaged as intended for sale
  • Special care is needed to maintain Modified Atmosphere Packaging (MAP) conditions following inoculation (e.g., must be monitored during challenge study)

Incubation of inoculated food products

  • Validation studies for changing the classification of a Category 1 into a Category 2A or 2B food must be performed at a temperature of 7 °C or above

Enumeration and enrichment methods

  • Samples should be diluted 1:5 (can use up to 1:10 for difficult to spread matrices)
  • Should use quantitative determination for Lm (e.g., MFLP-74 available in HC's Compendium)

Documentation of results

  • Document all results of the challenge study in a report
  • Include information on all required components of the challenge study
  • Raw data and any graphical representations/interpretations should be included

The experimental design must be detailed and rationale for each parameter should be included in the validation data.

Validation of RTE Foods for Re-Categorization

(Section 3.2 and 4.2 (c) of HC's Validation Document)

Identification of Key Process Parameters, and Provision of Evidence of their Control – Mandatory

  • Key process parameters (e.g., aw, pH) need to be clearly identified and documented
  • Adequate controls of key process parameters must be implemented and documented to provide evidence that the food safety outcome is not compromised
  • The same controls must be applied to the process parameters used in the challenge study

Validation of RTE Foods for Re-Categorization

(Section 3.2 and 4.2 (a)(d) of HC's Validation Document)

Literature Review – Recommended

  • Pertinent publications should include possible level of Lm contamination and growth profile in the RTE product(s) and/or similar products

Modeling – Optional

  • Mathematical modeling could be conducted for a group of similar RTE products
  • A challenge study must be performed on the RTE product which represents the highest risk for Lm within the grouping
  • A rationale supported by scientific evidence and the modeling documentation should be provided for evaluation

Validation – Additional Information

(Section 5 of HC's Validation Document)

  • After validation, if a change is made to a control measure or product, the appropriateness of the validation studies supporting the categorization of the RTE food may need to be confirmed.
  • If the change is determined by regulatory authority to be substantial, the need for re-validation/re-categorization may be triggered.

Other approaches to validation may be considered by the regulatory authority, on a case by case basis.

Validation – Summary

(Section 1 and 5 of HC's Validation Document)

  • It is the responsibility of the processor/importer to demonstrate in which category their RTE food belongs.
  • When industry wants to re-categorize a RTE product, validation studies should be completed according to HC's procedures.
  • Validation data should be submitted to the relevant regulatory authority (i.e., CFIA) for evaluation and confirmation.
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