Control measures for Listeria monocytogenes in ready-to-eat foods
Requirements for the Safe Food for Canadians Regulations
Although the Safe Food for Canadians Regulations [SFCR] came into force on January 15, 2019, certain requirements may apply in 2020 and 2021 based on food commodity, type of activity and business size. For more information, refer to the SFCR timelines.
Introduction
Listeriamonocytogenes [L. monocytogenes] is widely distributed in nature. It can be found in soil, sewage, vegetation, water, silage, livestock and humans. It is also well adapted to survival in the cold, moist environments commonly found in processing establishments.
Contamination of a food with L.monocytogenes is one of many biological hazards that should be considered during a hazard analysis and when developing a preventive control plan.
Certain individuals including the elderly, pregnant women and immunocompromised individuals are much more at risk if exposed to L.monocytogenes. Because of the potentially serious consequences, especially to certain groups within the population, food businesses need to pay particular attention to controlling this biological hazard.
Ready-to-Eat [RTE] foods contaminated with L.monocytogenes at levels exceeding 100 colony-forming units [CFU] of bacteria per gram of food have been implicated in outbreaks of listeriosis.
Health Canada's Policy on Listeriamonocytogenes in Ready-to-Eat Foods aims to enhance the control and verification of Listeria in the environment where food is prepared.
Purpose
The Canadian Food Inspection Agency [CFIA] created this document as guidance to help food businesses comply with the Safe Food for Canadians Regulations.
It's your choice
You may use other guidance developed by provincial governments, industry associations, international partners or academic bodies as long as they can achieve the outcomes identified in the regulations. Always ensure that the guidance you choose is relevant for your particular business, product or products, and market requirements
What is Listeria monocytogenes?
L. monocytogenes is a pathogenic bacterium that:
- is very hardy [resistant to drying, freezing and high salt concentrations]
- can grow readily at refrigeration temperatures
- can be destroyed by thoroughly cooking food
What is a Ready-to-Eat food?
A food is considered Ready-to-Eat [RTE] when it:
- does not require any further preparation before consumption, except washing or rinsing, thawing or warming
- has received some form of processing such as cooking to render it RTE and/or to extend its shelf-life [not including food in a hermetically sealed container that is commercially sterile]
What's included
This guidance is based on Health Canada's Policy on Listeriamonocytogenes in Ready-to-Eat Foods and is intended to help food businesses:
- establish control measures to prevent or eliminate the contamination of a food with L.monocytogenes
- determine the RTE risk category for L.monocytogenes
- establish procedures to monitor for the presence of L.monocytogenes in the establishment [environmental sampling program], as well as in RTE food
- determine the actions to take when L.monocytogenes or Listeria species [spp.] is found:
- on food contact surfaces
- on non-food contact surfaces
- in food
- conduct a trend analysis
The examples of control measures for L.monocytogenes are not exhaustive, control measures will depend on the size and complexity of the food operation and be unique for each business.
Refer to the Tell me more! section for additional sources of information that may help you develop control measures for L.monocytogenes.
What's not included
The document does not provide information on how to:
- obtain evidence showing a control measure is effective
- conduct a validation study for the purpose of applying a lower L.monocytogenes RTE risk category
- determine the shelf life of a food
The document does not address labelling requirements specific to RTE food. Labelling information can be found in CFIA's industry labelling tool.
Roles and responsibilities
Food businesses are responsible for complying with the law. They demonstrate compliance by ensuring that the commodities and processes for which they are responsible meet regulatory requirements. If a written preventive control plan [PCP] is required, the food business develops a PCP with supporting documents, monitors and maintains evidence of its implementation, and verifies that all control measures are effective.
The CFIA verifies the compliance of a food business by conducting activities that include inspection, and surveillance. When non-compliance is identified, the CFIA takes appropriate compliance and enforcement actions.
Listeriamonocytogenes in ready-to-eat foods
When conducting a hazard analysis for an RTE food, L.monocytogenes should be identified as a hazard that can present a risk of contamination to the food.
- Identify critical processing steps which may affect the risk classification, such as a lethality step, the use of L.monocytogenes growth inhibitors or pH adjustment
- Identify likely consumers of the RTE food
L.monocytogenes RTE risk category
RTE foods are classified in one of three risk categories based on the health risk L.monocytogenes poses if present in the food. The parameters used to determine the risk category are established in Health Canada's Policy on Listeriamonocytogenes in Ready-to-Eat Foods.
The risk categories are used to determine:
- the control measures and level of monitoring needed to prevent or reduce the risk of contamination of an RTE with L.monocytogenes
- the corrective actions needed to address deviations or inadequate control measures to prevent or reduce the contamination with L.monocytogenes
The following outlines the parameters for determining the L.monocytogenes risk category of a RTE food:
- Category1 product: an RTE food in which the growth of L.monocytogenes can occur
- This category applies to all RTE food that does not fall in category2A or 2B [below]
- Category2A product: an RTE food in which the growth of L.monocytogenes can occur but is limited to levels no greater than 100CFU/g over the course of the stated shelf-life
- This category applies to an RTE food that has a refrigerated shelf-life of 5days or less
Note: If the shelf-life exceeds 5 days, the RTE food could be classified a Category2A product - but only if a validation is conducted and demonstrates that the growth cannot exceed 100CFU/g. The Health Canada documents Validation of ready-to-eat foods for changing the classification of a category1 into a category2A or 2B Food - in relation to Health Canada's Policy on Listeriamonocytogenes in Ready-to-Eat Foods [2011] and Listeriamonocytogenes challenge testing of ready-to-eat refrigerated foods provide information on the validation of the L.monocytogenes RTE risk category.
- Category2B product: a RTE food in which the growth of L.monocytogenes cannot occur over the course of the stated shelf-life.
This category applies to a RTE food that meets the following parameters:
- products that are frozen, or
- have a pH < 4.4 regardless of the aw, or
- have water activity [aw] < 0.92 regardless of the pH, or
- have a pH < 5.0 and an aw < 0.94
Note: If the RTE food doesn't meet the above parameters, it would be classified a Category2B product only if a validation is conducted and demonstrates that the growth of L.monocytogenes cannot occur.
Control measures for L.monocytogenes
The following control measures could be applied to an RTE food to prevent or reduce the growth of L.monocytogenes.
Growth limiting parameters
L.monocytogenes has the ability to grow in an RTE food when the:
- temperature of the food is at -0.4 to 45 °C
- pH of the food is 4.4 or higher
- water activity [aw] is at 0.92 or higher
The pH and water activity [aw] of an RTE food can act as a growth limiting barrier for L.monocytogenes. The product formulation used to prepare an RTE food can be adjusted to bring these parameters to a level that can reduce or eliminate the growth of L.monocytogenes. For example, an RTE food will not support growth of L.monocytogenes when the product formulation results in a:
- pH