ARCHIVED - Policy on Listeria monocytogenes in Ready-to-Eat Foods
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Health Products and Food Branch
Version Number: 001
Issue Date: March 22, 2010
Table of Contents
- 1.0 Summary
- 2.0 Purpose and Scope
- 3.0 Roles and Responsibilities
- 4.0 Background
- 5.0 Scientific Basis for Listeria monocytogenes Criteria in Ready-to-Eat Foods
- 6.0 Compliance Criteria for Listeria monocytogenes in Ready-to-Eat Foods
- 7.0 Achieving Compliance with the Criteria for Ready-to-Eat Foods
- 8.0 Development of Educational Materials for Consumers and Others Involved in Food Handling and Preparation
- Appendix A: Definitions
- Appendix B: Major Reported Foodborne Listeriosis Outbreaks
- Appendix C: Use of Food Additives, Processing Aids and/or Post-Process Lethality Treatments for Ready-to-Eat Foods
The Canadian "Policy on Listeria monocytogenes in ready-to-eat foods" (hereafter referred to as the Listeria policy) is based on Good Manufacturing Practices1 (GMPs) and the principles of HACCP (Hazard Analysis Critical Control Point; see Appendix A). This policy was developed using a health risk assessment (HRA) approach and uses as its foundation a combination of inspection, environmental sampling2 and end-product testing to achieve control of L. monocytogenes in ready-to-eat (RTE) foods. Focus is given to environmental control, especially in post-processing areas. The present policy revises and replaces the Policy on Listeria monocytogenes in ready-to-eat foods dated October 4, 2004.
The current policy differs from the 2004 document in the following:
- New end-product compliance criteria have been developed. These are in line with the International Codex Alimentarius Commission standards (CAC, 2009a).
- The definitions of RTE foods in which growth of L. monocytogenes can or cannot occur have been modified and/or developed and the list of food products implicated in listeriosis outbreaks has been updated.
- The compliance action decision tree, including environmental testing for Listeria spp.3 and end-product testing for L. monocytogenes, has been modified to include more details related to sampling.
- It now states that an environmental monitoring program should be included in all plants used in the production of RTE foods, as defined in this policy.
- It lists and encourages the use of post-process lethality treatments and/or L. monocytogenes growth inhibitors.
- There is an increased focus on outreach with the federal/provincial/territorial community to increase awareness of the risks of foodborne listeriosis and to provide guidance on how to reduce the risks of acquiring listeriosis to personnel in institutions where high-risk people may be exposed.
In this policy, RTE foods have been classified into two categories, based upon health risk. Category 1 contains products in which the growth of L. monocytogenes can occur (see Appendix A). These should receive the highest priority for industry control, as well as regulatory inspection and compliance activities. The presence of L. monocytogenes in these Category 1 RTE foods will likely trigger a Health Risk 1 concern. Category 2 contains two subgroups: 2A) RTE food products in which limited growth of L. monocytogenes to levels not greater than 100 CFU/g can occur before the end of the stated shelf-life; and 2B) RTE food products in which the growth of L. monocytogenes cannot occur throughout the expected shelf life of that food (see Appendix A). These products should receive a lower priority with regards to industry control, as well as regulatory inspection and compliance action.
This revised policy should lead to an enhancement of the control of Listeria spp. in the food processing environment, permit earlier identification of any potential persistent contamination of the plant environment and provide an increased ability to identify and mitigate against L. monocytogenes contamination of finished product. These actions will provide an early warning and permit the appropriate interventions to protect consumers.
2. Purpose and Scope
The goal of this policy is to protect the health of Canadian consumers and to provide guidance to industry and regulatory authorities regarding the control of L. monocytogenes in RTE foods. It also provides guidance to regulatory authorities regarding inspection and compliance actions of RTE foods contaminated with L. monocytogenes.Consistent with the current knowledge that the risk of listeriosis is increased in RTE foods which support the growth of L. monocytogenes and which have extended shelf-lives, priority is placed on RTE foods in which the growth of L. monocytogenes can occur. In addition to providing guidance to other food safety regulators (e.g., the Canadian Food Inspection Agency and provincial/territorial governments) and decision-makers, this policy can also guide RTE food producers in their verification activities with respect to the presence of L. monocytogenes in both the plant environment and the finished product. In addition to what is outlined in this policy document, additional regulatory requirements specific for particular food commodities may also be applicable.
3. Roles and Responsibilities
This policy, developed as a joint effort between Health Canada (HC), the Canadian Food Inspection Agency (CFIA) and the Public Health Agency of Canada (PHAC), takes into account the roles and responsibilities of industry, government and consumers.
It is industry's role and responsibility to comply with all applicable legislative and regulatory requirements which includes Sections 4 and 7 of the Food and Drug Act (Department of Justice Canada, 2008). As L. monocytogenes can be found in the environment of food processing plants, RTE food producers should have an effective GMP and/or HACCP system to minimize all potential sources of food contamination. This will address L. monocytogenes in the environment of the manufacturing plant, foodservice and retail establishments. They should also strongly consider introducing within their food safety systems one or more validated controls for the elimination of L. monocytogenes from their products (e.g., use of a post-process lethality treatment). Furthermore, environmental and end-product sampling schemes and the use of microbiological testing as a verification tool to demonstrate the efficacy of the control measures put in place to address L. monocytogenes are recommended. Food processing plants should carry out regular environmental sampling, as described in Figures 1, 2 and 3, to verify the effectiveness of their sanitation program for controlling Listeria spp.in the plant environment, and should increase sanitation efforts and control measures in areas where Listeria spp. are found.
Health Canada develops food safety standards and policies to help minimize the risk of foodborne illnesses. It is the role of the CFIA and provincial/territorial governments to carry out inspection of the food industry to verify and enforce that it meets Canadian food safety responsibilities (Health Canada, 2008). The role of the PHAC is to promote and protect the health of Canadians through leadership, partnership, innovation and action in public health (PHAC, 2007). The PHAC, the CFIA and Health Canada work together with public health officials and provincial/territorial ministries of health to investigate the source of any Listeria-related illnesses when an outbreak is suspected. In addition, the three federal departments provide reference laboratory services, conduct food safety investigations, HRAs and recall actions.
It is also the role of the government of Canada to brief the medical community, public health officials, the food industry and consumers on many issues related to L. monocytogenes and listeriosis.
In addition to government agencies and food industries working diligently to minimize the exposure to L. monocytogenes, consumers also have an important role to play in the farm-to-fork continuum. That role calls for Canadians to learn and adopt safe food handling, responsible food selection and preparation practices (Health Canada, 2008). To this end, Health Canada, the CFIA and the PHAC (and other provincial/territorial bodies) have in the past, and will continue in the future, to be committed to the development and delivery of science-based educational material to inform consumers and others about the hazards associated with L. monocytogenes in RTE food and how to minimize the risks of foodborne disease.
L. monocytogenes is a bacterial pathogen that is widely distributed in nature. It has been isolated from faecal specimens of healthy animals and humans, as well as from sewage, silage, soil, fertilizer, vegetable matter and many foods (Farber and Peterkin, 1991; Farber and Peterkin, 2000; McLauchlin et al., 2004). Important characteristics of this organism include its ability to grow at temperatures of -0.4 to 45 °C, pH values of 4.4 or greater and water activities (aw) of 0.92 or higher (ICMSF, 1996).
It is estimated that up to 5 % of humans may carry L. monocytogenes in their intestines without ill effects. This organism, however, is recognized as the causative agent of the infection known as listeriosis. Listeriosis can manifest itself in two different forms, namely invasive and non-invasive. Invasive listeriosis usually develops in people with compromised immune systems while non-invasive listeriosis can develop in any population if large numbers of bacteria (e.g., > 103 CFU/g) are consumed. Several modes of transmission have been identified: mother-to-foetus infection in utero or infection during childbirth, infant-to-infant, animal-to-human and, most importantly, transmission to humans through consumption of contaminated food (McLauchlin, 1993; McLauchlin et al., 2004).
Serious infections of L. monocytogenes are manifested by septicaemia and/or meningitis, and may result in death. The highest incidence of listeriosis is amongst pregnant women, the elderly (> 60 years of age) and immunocompromised individuals. Among the elderly, the risk increases as individuals age, i.e., as compared to healthy individuals 40 to 59 years of age, Canadian data show that persons aged 65 to 69 years of age have a 4-times increased risk, while those aged 75 to 79 years of age have nearly a 9-times increased risk (PHAC, 2009a). Infection of healthy adults is relatively rare. Symptoms are typically mild in pregnant women, however, the passage of the organism through the placenta may cause miscarriage, stillbirth, or perinatal septicaemia and meningitis in the newborn baby. Listeria monocytogenes is more likely to cause death than other bacteria that cause foodborne illness, i.e., 20-30 % of foodborne listeriosis infections in high-risk individuals may be fatal (Health Canada, 2008). In fact, the potential health outcomes from listeriosis could be serious and/or long-lasting (Roberts et al., 2009).
A number of foodborne outbreaks have been documented throughout the world (Appendix B). Listeriosis outbreaks have been attributed to RTE food products such as pâté, unacidified jellied pork tongue (i.e., in aspic), rillettes, frankfurters, certain deli meats, chicken wrap, soft cheese made from either raw or pasteurized milk, pasteurized milk (including chocolate milk), butter, frozen ice cream cake, whipping cream, coleslaw, fruit salad, RTE fish products such as smoked mussels, gravlax (aka. gravad) or cold-smoked trout, imitation crab meat, shrimp, prepackaged sandwiches, as well as rice and corn salads.
In Canada, the national reported rate of listeriosis has increased over the last several years from 2.3 cases per million population in 2000 to 4.2 cases per million population in 2007, i.e., 2.3, 2.9, 2.9, 3.4, 3.0, 3.3, 3.9 and 4.2, respectively (PHAC, 2009b; Clark et al., 2009). A sharp increase in incidence was noted in 2008, with 7.2 cases per million population reported (PHAC, 2009a). This was largely attributable to two large outbreaks involving 57 and 38 confirmed cases, respectively (PHAC, 2008; MSSS, 2009/MAPAQ, 2009). France, the United Kingdom and several other European countries have also reported increases in the incidence of listeriosis over the last several years. In these countries, the increase has been predominantly driven by an increased incidence in patients > 60 years of age. The reasons for this increase are unknown (Gillespie et al., 2006; Goulet et al., 2008; ACMSF, 2009).
5 Scientific Basis for Listeria monocytogenes Criteria in Ready-to-Eat Foods
The foods implicated in major outbreaks of listeriosis worldwide are typically those in which L. monocytogenes is present at or can grow to levels that could present a risk to consumers (see Appendix B). In general, the risk of acquiring foodborne listeriosis increases depending on factors such as host susceptibility, the amount and frequency of consumption of a food contaminated with L. monocytogenes, the frequency, distribution and level of L. monocytogenes in the food, the potential for growth of L. monocytogenes in the food during refrigerated storage, the refrigerated storage temperature and/or the duration of refrigerated storage before consumption (FAO/WHO, 2004a). Therefore, the policy considers the levels of L. monocytogenes in a food and the potential for growth of L. monocytogenes in a particular food. This is based on factors such as pH, water activity, the presence of preservatives and storage conditions, e.g., temperature and shelf-life.
Canadians consume foods contaminated with L. monocytogenes on a regular basis, however, the incidence of listeriosis remains relatively low. The incidence of L. monocytogenes in RTE foods ranges from 0 to 10 % (Farber and Peterkin, 2000; Ryser and Marth, 2007; Gombas et al., 2003; Little et al., 2009). A large US study found that the prevalence of L. monocytogenes in RTE products such as smoked seafood, luncheon meats, salads (seafood, bagged precut leafy vegetable and deli) and cheeses (fresh soft, blue-veined, and mold-ripened) ranged from 0.17 to 4.7 % (Gombas et al., 2003). In addition, a recent UK study found that the prevalence of L. monocytogenes in RTE products such as RTE sliced meats, hard cheeses, sandwiches, butter, spreadable cheese, confectionery products containing ice cream and probiotic drinks ranged from 0 to 7. 0 % (Little et al., 2009).
A definitive dose-response model for L. monocytogenes in humans has yet to be established. However, based on current case data from around the world, the likelihood of any one food contaminated with low numbers of L. monocytogenes resulting in illness is considered to be remote (FAO/WHO, 2004b). Foods containing low levels of L. monocytogenes (e.g., < 100 CFU/g) pose very little risk (Chen et al., 2003; FAO/WHO, 2004b). In fact, in instances where foods linked to listeriosis outbreaks were still available for testing, the levels of L. monocytogenes detected both from unopened foods and leftover foods obtained from the patients have usually been high (i.e., >103 CFU/g), and thus were due to non-compliant samples (European Commission Health and Consumer Protection Directorate-General, 1999). Consequently, a lower priority should be placed on products in which the organism cannot grow or, has a limited potential for growth whereby the levels do not exceed 100 CFU/g at the end of the stated shelf-life (see Table 1). At the international level, the Codex Alimentarius Commission and the Commission of European communities have proposed similar microbiological criteria for the control of L. monocytogenes in RTE foods, with a view towards protecting the health of consumers while ensuring fair practices in food trade (European Communities, 2007; CAC, 2009a). The U.S. risk assessment, which included a risk categorization of foods (FDA/FSIS, 2003), further supports the fact that RTE foods differ in their ability to support growth and being linked to listeriosis. In addition, the USFDA recently published a draft compliance policy guide, in which RTE foods that do not support the growth of L. monocytogenes would only be considered adulterated if the organism was present at ≥ 100 CFU/g (USFDA, 2008).
6 Compliance Criteria for Listeria monocytogenes in Ready-to-Eat Foods
6.1 Assignment of Risk Classification of Ready-to-Eat Foods According to Consumer Risk (Categories 1 and 2: see Table 1)
Category 1 RTE foods:
Category 1 RTE foods are those foods which can support the growth of L. monocytogenes. As presented earlier, Category 1 RTE foods should receive the highest priority for industry control, as well as regulatory inspection and compliance activities. The presence of L. monocytogenes in a Category 1 food when the specified sampling plan and analysis are applied, will be classified as a Health Risk 1, as determined in Table 1: "Compliance criteria for L. monocytogenes in RTE foods". A public alert and recall will likely be issued if the food has left the control of the producer (Health Risks 1 and 2 are defined in Appendix A). The implicated product may be considered to be in violation of sections 4 and 7 of the Food and Drugs Act (Department of Justice Canada, 2008). Different risk management actions may occur in cases where the food producer is able, as part of the safety evaluation, to present data which demonstrate that the growth of L. monocytogenes will not occur in the product, for example, the validated use of preservatives, etc. As part of the compliance action in such cases, arrangements for an HRA, performed by the Evaluation Division of the Bureau of Microbial Hazards (BMH), could be made by the responsible authority.
Category 2 RTE foods:
Category 2 is subdivided into: 2A) RTE food products in which limited growth of L. monocytogenes to levels not greater than 100 CFU/g can occur before the end of the stated shelf-life; and 2B) RTE food products in which the growth of L. monocytogenes cannot occur throughout the expected shelf life of that food. These products should receive a lower priority with regards to industry control, as well as regulatory inspection and compliance action.
Category 2A RTE foods:
This category is meant to include, for example, foods which may contain persistent low levels of L. monocytogenes and do not have a kill step, and/or RTE refrigerated foods with a shelf-life of ≤ 5 days. The latter time period would not allow sufficient time, under reasonably foreseeable conditions of distribution, storage and use, for L. monocytogenes to grow to levels above 100 CFU/g by the end of the stated shelf-life. Other foods with a shelf-life greater than 5 days, e.g., cold-smoked salmon, fresh-cut produce, although they are frequently consumed, have not been linked to large documented outbreaks of listeriosis. Notwithstanding that these foods can support the growth of L. monocytogenes, the growth is generally limited because of a number of factors such as short refrigerated shelf-life, a large background microflora containing anti-Listeria lactic acid and/or other bacteria, etc. These Category 2A foods should receive a medium-low priority, with regards to the level of inspection and compliance activity. For these foods, operators would need to validate that the levels of L. monocytogenes are consistently equal to or less than 100 CFU/g during the whole shelf-life of these products. In general, operators should monitor their products, from time to time, to ensure that they meet the criteria (e.g., limited potential for growth of L. monocytogenes to levels not greater than 100 CFU/g during the whole stated shelf-life) that justify their classification in this category.
Category 2B RTE foods:
Since these foods do not support the growth of L. monocytogenes, they should receive a low priority, with regards to the level of inspection and compliance activity. In general, operators would only need to monitor their products, from time to time, to ensure that they meet the criteria (e.g., physico-chemical parameters such as pH and aw) that justify their classification in this category.
Some frozen RTE foods, otherwise considered as Category 2, may be temperature-abused, causing them to thaw and thereby could potentially permit the growth of L. monocytogenes. Additionally, some Category 2 products may be intended for use in Category 1 products (e.g., frozen smoked fish used to make a refrigerated smoked fish mousse) or, some RTE foods may be destined for persons at high-risk, e.g., immunocompromised, elderly, pregnant, etc. A finding of L. monocytogenes in the above foods would lead to follow-up action(s) and hence, a HRA may be required on a case-by case basis, to be conducted by the BMH, in order to determine the compliance action to be taken. These Category 2 foods may be assessed to represent a Health Risk 1 concern.
6.2 Applying the Criteria to Domestic and Imported Ready-to-Eat Foods and Foods Targeted to High-Risk Population Groups
The relative importance of verifying the controls for L. monocytogenes in the processing environment depends on the risk to consumers if the food becomes contaminated. Inspectors of domestic establishments should encourage adherence to the principles of GMP and the HACCP system. If inspection reveals inadequate application of GMPs that could lead to post-process contamination of a RTE food, a review of the producer's control program for Listeria spp. should be conducted. This review should take into account previous environmental and end-product testing results. If the review does not verify that Listeria spp. is controlled, increased environmental sampling should be undertaken by the operator/producer to determine whether Listeria spp. is present. If so, the positive results of samples should be taken as evidence for the need to improve control of Listeria spp. In addition, if two (Category 1) or more (Category 2) FCS environmental samples test positive, end-product testing should be initiated to ensure that finished product is not contaminated with L. monocytogenes.
Increased knowledge of the ecology of L. monocytogenes in RTE food products has clarified which products can or cannot support the growth of L. monocytogenes. This has permitted the classification of RTE foods for which specific compliance action may be needed. The nature of concern should be determined based on the information in Table 1. Sampling priority should be given to Category 1 RTE products. Although Category 2A and 2B products are of lesser concern than Category 1 RTE foods, sampling at times may still be warranted. RTE food producers, in consultation with the regulatory authority, should a) attempt to determine the source of the contamination using inspection, environmental sampling and end-product testing, and b) take the appropriate corrective actions. The actions taken need to reflect the findings of the investigation that is done when unsatisfactory results are obtained. They may include, without being limited to, the following: i) requiring minimum follow-up tests (Figures 1, 2 and 3); ii) increasing and/or correcting sanitation procedures; iii) obtaining additional data to confirm hypotheses when doing root cause analysis; iv) developing and implementing an enhanced sampling plan (for the affected line and possibly the product); and v) revisiting the HACCP system and adjusting it, if necessary. Corrective actions must be monitored to confirm their efficiency. The whole process should be documented, as this information analysis can be integrated in the establishment's trend analysis activities.
Imported RTE products:
Canadian food importers must import food products that are in compliance with relevant Canadian legislation. The importer should be able to demonstrate that the food products are safe and meet these requirements. Information regarding the product(s) imported, including information about the supplier, producer or exporter is most useful, and should serve as background information to determine what verification activities are required. As well, the importer should ensure that safe food storage and handling procedures are in place at the importer's facility.
Inspection of imported RTE foods is intended to ensure an equivalent level of protection to consumers of both imported and domestic products. Canadian food regulatory agencies, however, may be unable to evaluate whether imported foods have been manufactured using effective GMPs and the HACCP system. Therefore, other verification measures such as end-product testing may be required to assess whether these products meet the criteria in Table 1. If sampled, the appropriate sampling plan and method of analysis, as specified in Table 1, should be applied. If insufficient, inadequate or no information exists regarding the categorization of the imported RTE product, it should, by default, be considered a Category 1 food and hence, the sampling plan and method of analysis for Category 1 foods, as specified in Table 1, should be applied. If questions arise, it is the responsibility of the importer to demonstrate what category the RTE food belongs to. Compliance action may be taken against lots that exceed the criteria.
Compliance action should be taken on a lot-by-lot basis and should not differ from that for domestic products. Importers should have a system in place to ensure that Canadian regulatory authorities will be able to differentiate individual lots based on clear product markings. If a shipment cannot be distinguished into individual lots, then the entire shipment would be considered as a single lot for inspection and compliance action.
Exported RTE products:
Canadian food exporters are responsible for exporting food products that meet the requirements of the receiving country, as well as the provisions of Section 37 of the Food and Drug Act Department of Justice Canada, 2008).
RTE Foods Targeted to High-Risk Population Groups:
RTE foods that are produced primarily for consumption by individuals who are known to be in the high-risk category (e.g., pregnant women, the elderly and immunocompromised individuals), may be considered to represent a Health Risk 1 and not Health Risk 2 concern, irrespective of product type.
7 Achieving Compliance with the Criteria for Ready-to-Eat Foods
7.1 Requirements for the Manufacture of Ready-to-Eat Food Products
The policy is based on a combination of manufacturing control measures (by industry), inspection (by regulatory authorities), as well as environmental sampling and end-product testing that should be undertaken by both industry and regulatory authorities.
RTE food producers should implement adequate controls to ensure their products are in compliance with the criteria in Table 1. It should be assumed that many incoming raw ingredients may contain L. monocytogenes. Thus, when feasible, industry should apply procedures that are validated to eliminate or reduce L. monocytogenes in the raw materials in order to comply with the criteria for L. monocytogenes in RTE foods. The potential for recontamination with L. monocytogenes should also be controlled and is influenced by factors such as plant layout, equipment design and maintenance, effectiveness of sanitation procedures and employee practices (CAC, 2007; Meat Industry Listeria monocytogenes Working Group, 2010).
In general, the concern for survival of L. monocytogenes can be managed through the HACCP system, which includes the use of validated critical control points (CCPs) and appropriate monitoring and verification procedures for each CCP. Procedures for validating pathogen reduction steps and strategies such as the use of additives to prevent growth, have a long history of use for a variety of foodborne pathogens. The concern for recontamination is managed through the application of GMP procedures, which require thorough and regular adherence due to the prevalence of L. monocytogenes in the environment, ease of dispersal, and ability to grow in the RTE processing environment (Meat Industry Listeria monocytogenes Working group, 2010). Several documents are available for guidance (Tompkin et al., 1999; NFI/NFPA, 2002; CAC, 2007; Meat Industry Listeria monocytogenes Working group, 2010). In addition, workshops sponsored by industry trade associations can be very effective for teaching current best practices within specific segments of industry.
Also helpful to industry is direct on-site observation which is a valuable means to assess compliance with the GMPs that can influence the presence of Listeria spp. (CAC, 2007). It is not possible, however, to predict by direct on-site observation alone, the degree to which Listeria spp. may occur in areas where RTE foods are exposed before final packaging. Many existing food processing facilities were not originally designed for the control of pathogens with the unique characteristics of L. monocytogenes. However, each food processing facility should be managed following best practices recognizing that the control of Listeria spp. is necessary for consumer protection. Modifications can often be made to control Listeria spp. in the environment and to reduce the risk of product contamination. An effective environmental monitoring program, supported by investigative sampling to detect sources of Listeria spp., should be used to identify the changes that may facilitate the control needed to ensure compliance with the criteria (Table 1). Experience indicates that environmental sampling is the most sensitive tool to assess control of the environment and risk of product contamination (Tompkin et al., 1992; Tompkin, 2002).
7.2 Environmental Sampling (Figures 1, 2 and 3)
Figures 1 and 2 outline the steps for sampling FCSs and RTE foods. Figure 3 outlines steps involved in sampling non-FCSs. Guidance for environmental sampling and testing should be conducted according to MFLP-41A and B (Health Protection Branch, 1992; Health Products and Food Branch Microbiological Methods Committee et al., 2006) as well as HPB Method (MFHPB) 30 (Pagotto et al., 2001), respectively, or equivalent microbiological methods, as outlined in Health Canada's Compendium of Analytical Methods. The relative importance of verifying control of the processing environment should be reflective of the risk to consumers if the food becomes contaminated. Of highest concern are i) foods that do not contain validated inhibitors of listerial growth (e.g., lactate, diacetate); ii) foods in which growth of L. monocytogenes to levels >100 CFU/g can occur during the shelf-life of the food; iii) foods which are not subjected to a listericidal treatment in the package before distribution and; iv) foods which are targeted to a sensitive population. The same factors should be considered when establishing the frequency and extent of sampling of the environment. Particularly for foods in which L. monocytogenes can grow during the product's shelf-life, the monitoring and control programs should be sufficiently strong (e.g., regarding sampling selection, frequency of sampling, numbers of samples, method of sampling, etc.) to enable producers and regulatory authorities to conclude when reviewing the data that the foods being produced are not contaminated with L. monocytogenes (CAC, 2007; Meat Industry Listeria monocytogenes Working Group, 2010).
Each establishment's Listeria control program should be designed to reflect current knowledge and experience that L. monocytogenes can be reduced to a level in the environment that ensures product will not become contaminated. However, the possibility exists that Listeria will be re-introduced into areas in which RTE foods are exposed. These factors emphasize the need to maintain an environmental sampling program that is adequate to manage consumer risk in relation to the Category of RTE food being produced (Table 1). It is important to continually strive for negative results by responding to each positive sample with appropriate corrective actions in a timely manner.
Establishments producing RTE foods should design, implement and maintain an environmental sampling program for testing FCS and non-FCS for the presence of Listeria spp. Testing for Listeria spp. and reacting to positive results as if they were L. monocytogenes provides for a more sensitive control program, than would testing for L. monocytogenes alone (Meat Industry Listeria monocytogenes Working group, 2010). It is recommended that Listeria spp. be used for monitoring the environment as outlined in Figures 1, 2 and 3. Listeria spp. provides a broader measure of control. The purpose of the environmental sampling program is to assess the effectiveness of sanitation and other GMPs in RTE processing environments and the potential for product contamination. Also, by detecting and responsibly responding to each positive result, consumer risk can be minimized. Environmental monitoring programs should include routine sampling of FCS that come into contact with exposed RTE foods before final packaging. Sponge/swab samples from surface areas of equipment should be collected during production, typically no sooner than or after 3 hours of operation. Guidance for environmental sampling can be found in the Health Canada's Compendium of Analytical methods, under MFLP-41A and B (Health Protection Branch, 1992; Health Products and Food Branch Microbiological Methods Committee et al., 2006). The number of sites (e.g., 1 - 10) will vary according to the complexity of the processing system or packaging line. 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). Increase in sample sites (FCSs and non-FCSs) and frequency should be considered during and/or after special circumstances (e.g., unsatisfactory results, construction, the installation of new or modified equipment), which may provide an opportunity for control of L. monocytogenes to be lost.
In some situations, food in various stages of processing or aggregate residual food materials can be used as additional samples to further assess the presence of Listeria along a processing line or system. Samples should also be collected from non-FCS as an additional measure of verification. Recent publications (CAC, 2007; Meat Industry Listeria monocytogenes Working Group, 2010) can provide guidance on the establishment of an environmental sampling program.
Investigational sampling differs from the routine environmental program used to monitor control of Listeria. It involves collecting additional samples from sites to help identify more clearly the source(s) of contamination. Investigational sampling is a valuable tool for identifying and eliminating harbourage sites (Tompkin, 2002; CAC, 2007). The benefit of environmental sampling for products given a validated final in-package listericidal treatment is affected by the degree of inactivation delivered by the listericidal process, e.g., cook-in-bag roast beef.
The finding of L. monocytogenes in a RTE food indicates that the establishment's control program is not adequate to prevent product contamination. When reviewing data for trend analysis, contamination of non-FCS with Listeria spp. in areas of the plant environment where RTE foods are exposed to post-process contamination is evidence that the Listeria control is inadequate and will be considered unsatisfactory. It is the responsibility of producers of RTE food to react to all unsatisfactory environmental results in a timely manner and to ultimately achieve Listeria-negative results. A finding of Listeria spp. in the RTE production environment should trigger follow-up actions (e.g., corrective actions coupled with intensified cleaning and sanitizing, timely re-testing of the contaminated area, testing of end-products that were potentially in contact with the positive FCS, in-depth review of the plant's food safety system, etc.). In general, non-FCS contamination with Listeria spp., including L. monocytogenes, usually precedes FCS contamination, thereby highlighting the importance of environmental controls (Tompkin et al., 1999; D'Amico and Donnelly, 2008). The guidance provided in Figures 1, 2 and 3 should be followed.
If two or more samples from the same area or packaging line 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. Persistent contamination of FCS with any Listeria spp. in the RTE plant environment could be an indication of inadequate GMPs. Appropriate follow-up actions are necessary when unsatisfactory results are obtained, taking into account the type and/or location of the sampling sites, and the category of food (see Figures 1, 2 and 3).
All positive results for L. monocytogenes in a RTE food or persistent Listeria spp. (e.g., consecutive positive results for Listeria spp.) on a FCS, should be communicated as soon as possible to the regulatory authority having jurisdiction, as per Figures 1 and 2.
Figure 1: Sampling Guidelines for FCS and Ready-to-Eat Foods in Category 1
Figure 2: Sampling Guidelines for FCS and Ready-to-Eat Foods in Category 2
Figure 3: Sampling Guidelines for non-FCS
7.3 Sampling and Analysis of Finished Ready-to-Eat Foods
For most RTE products, control (i.e., by adequate sanitation and GMPs) and verification of the environment (i.e., by an appropriate environmental sampling plan) is a more desirable approach to control L. monocytogenes. Therefore, a better decision can be made regarding releasing end-products rather than relying on testing individual lots. However, end-product testing is conducted for various reasons, such as customer requirements, evaluation of product contamination when FCS tests positive for Listeria spp. (as stipulated in Figures 1 and 2), periodic testing to determine control of process/GMPs, foreign country requirements, regulatory testing, verification of antimicrobial treatments, incoming product testing, testing of marketed products as part of an investigation and trend analysis, etc. When testing end-products, producers should develop:
- written procedures for end-product testing with details on any hold and test procedures
- sampling procedures
- sampling frequency and size
- methodology and
- proposed follow-up actions
It is recommended that all implicated end-products be held pending results from routine testing, as per Table 1 "Compliance criteria for L. monocytogenes in ready-to-eat (RTE) foods".
Samples of all finished RTE food products submitted for the analysis of L. monocytogenes will consist of 5 sample units of at least 100 g each (Table 1), which are representative of the lot and the production conditions, taken at random from each lot. Sampling of imports, particularly of large shipments, should be applied to identifiable lots of the product. Where the importer is unable to provide information on the identity of different lots, then the entire shipment would be treated as a single lot.
Category 1 RTE foods:
Analysis of Category 1 RTE foods for the presence of L. monocytogenes should be conducted according to HPB Method (MFHPB) 30 (Pagotto et al., 2001) or equivalent microbiological methods, as outlined in Health Canada's Compendium of Analytical Methods. An analytical sample size of 5 X 25g for this specific category of RTE product should be used for routine end-product testing.
Category 2 RTE foods:
For the analysis of all Category 2 RTE foods, a quantitative analysis should be conducted according to Laboratory Procedure (MFLP) 744 (Pagotto et al., 2002) or equivalent microbiological methods, as outlined in Health Canada's Compendium of Analytical Methods. An analytical sample size of 5 X 10g for this specific category of RTE product should be used for routine end-product testing. This will determine the CFU/g, of L. monocytogenes in the food, above the action level (i.e., 100 CFU/g). The detection of L. monocytogenes in a finished Category 2 RTE food requires follow-up as described in Figure 2. The presence of L. monocytogenes at low levels (≤ 100 CFU/g) in a product could be an indication of inadequate application of GMPs, and/or a process that cannot ensure non-detectable levels of L. monocytogenes.
The appropriate regulatory authority should be notified upon any positive end-product results and follow-up actions should be implemented to ensure that the producer has the situation (i.e., including all implicated RTE end-products) under control. Corrective actions, to be undertaken by the company and/or regulatory authorities, such as a review of the company's Listeria control strategy including GMPs, intensive cleaning and sanitation, additional environmental and end-product testing, are all strongly recommended.
Table 1: Compliance Criteria for L. monocytogenes in Ready-to-Eata Foods
|Category||Methods||Sampling||Analysis||Type of analysis||Action level for L. monocytogenes||Nature of concern||Level of Priority|
|1. RTE foods in which growth of L. monocytogenes can occurb before the end of the stated shelf-life (e.g., deli meats, soft cheeses, hot dogs, pâté)||MFHPB-30c||5 sample units (min 100 g or ml each), which are representative of the lot and the production conditions, taken aseptically at random from each lot||5 x 25 g analytical unitsd are either analysed separately or composited||Enrichment only||Detected in 125g e, f||Health Risk 1 g||High|
|2 A) RTE foods in which a limited potential for growth of L. monocytogenes to levels not greater than 100 CFU/g can occurb before the end of the stated shelf-life. A number of factors will be taken into consideration with regards to which foods may fall into this Category (see Section 7.1):
Such foods could include: refrigerated gravlax/cold-smoked rainbow trout and salmon, fresh-cut produce, etc.
|MFLP-74c||Same as above||5 x 10 g analytical unitsd||Direct plating
|> 100 CFU/g i, j||Health Risk 2 g, k||Medium-Low|
|2 B) RTE foods in which growth of L. monocytogenes can not occurh before the end of the stated shelf-life (e.g., ice cream, hard cheese, dry salami, dried-salted fish, varieties of prosciutto ham)||Low|
a- For a definition of RTE foods, see Appendix A.
b- For a definition of RTE foods in which growth of L. monocytogenes can occur, see Appendix A.
c- Published method in the Compendium of Analytical Methods from Health Canada or its equivalent method.
d- The designated analytical unit is taken from each sample unit.
e- MFHPB-30 or equivalent method; presence or absence by enrichment only (Pagotto et al., 2001; Compendium of Analytical Methods).
f- Assuming a log normal distribution, this sampling plan would provide 95% confidence that a lot of food containing a geometric mean concentration of 0.023 CFU/g and an analytical standard deviation of 0.25 CFU/g would be detected and rejected if any of the five samples are positive for L. monocytogenes (CAC, 2009a).
g- For a definition of health risk categories, see Appendix A.
h- For a definition of RTE foods in which growth of L. monocytogenes will not occur, see Appendix A
A RTE food in which growth of L. monocytogenes will NOT occur (CAC, 2009a) includes the following:
- pH < 4.4, regardless of aw
- aw < 0.92, regardless of pH
- combinations of factors (e.g., pH < 5.0 and aw < 0.94)
- frozen foods
The pH and aw should be determined for at least 3 out of 5 analytical units. The growth of L. monocytogenes is presumed to occur, if any one of the analytical units falls outside the range of pH and aw values in which the growth of L. monocytogenes will not occur (as above). For a more complete definition of RTE foods in which growth of L. monocytogenes will not occur, see Appendix A.
i- MFLP-74 or equivalent method; enumeration done by direct plating onto selective agar (Pagotto et al., 2002; Compendium of Analytical Methods).
j- Assuming a log normal distribution, this sampling plan would provide 95% confidence that a lot of food containing a geometric mean concentration of 93.3 CFU/g and an analytical standard deviation of 0.25 log CFU/g would be detected and rejected based on any of the five samples exceeding 100 CFU/g L. monocytogenes (CAC, 2009a).
k- This becomes a Health 1 concern if the product is targeted or distributed to a sensitive population such as the elderly, pregnant women or immunocompromised individuals (AIDS patients, transplant recipients, cancer patients, etc.), or if the product is intended for use in a Category 1 product.
Note: If insufficient, inadequate or no information exists regarding the categorization of the imported RTE food product, it will, by default, be considered a Category 1 food and hence, the sampling plan and method of analysis for Category 1 foods, as specified in Table 1, should be applied. If questions arise, it is the responsibility of the importer to demonstrate what category the RTE food belongs to.
7.4 Importance of Trend Analysis and Quality Assurance Tools
An establishment cannot rely solely on end-product testing to control Listeria. Its food safety management system should apply modern quality control and statistical methods to monitor its processes and detect time and/or spatial patterns (trends) suggestive of contamination sources that can be further investigated and mitigated. Where possible, these should include modern graphical techniques, such as control charts, Pareto diagrams, etc. as well as appropriate descriptive and analytical statistical methods. All data and analysis results should be made available to those in the firm responsible for managing the Listeria control program. Responsibility for updating and disseminating the data should be assigned to one or more individuals within the establishment (e.g., quality assurance, food safety and/or HACCP coordinators). On-going review and analysis of the data for Listeria spp. from routine monitoring programs should be performed to detect trends before major issues develop. Such reviews also provide information on the prevalence of Listeria spp., their fluctuations over time and identify issues to be addressed in a timely manner. Attention should be given to the dates and locations of positive samples to determine if low level and/or sporadic positives occur at certain locations that may have gone unnoticed previously (CAC, 2007). Trend analysis should be used to achieve improved control over time as each establishment gains experience in controlling Listeria and makes appropriate adjustments.
8 Development of Educational Materials for Consumers and Others Involved in Food Handling and Preparation
The aim of developing educational materials is to educate, inform and increase awareness of food hazards associated with RTE foods for consumers in general, and more specifically for seniors and their caregivers, pregnant women, people with weakened immune systems and other potentially high-risk individuals about safe food handling practices, and what they can do to reduce the risk of acquiring foodborne listeriosis. While significant information already has been provided by various levels of government, collaboration between the federal and provincial/territorial and municipal governments, will ensure that consumers receive reliable and consistent information so that they can make better informed choices and/or learn how foods should be properly handled and prepared. To this end, Health Canada will seek the collaboration of the PHAC, the CFIA and the Provinces/Territories for future work in this area.
8.1 Contributions of Health Canada Scientists to Published Information Related to Foodborne Listeriosis
- Clark, C.G., Farber, J.M., Pagotto, F., Ciampa, N., Doré, K., Nadon, C., Bernard, K., Ng, L.-K. and the Canadian Public Health Laboratory Network. (2009). Surveillance for Listeria monocytogenes and listeriosis in Canada, 1995-2004. Epidemiol. Infect., 12: 1-14.
- Farber, J.M., Pagotto, F. and Scherf, C. (2007). Incidence and behaviour of Listeria monocytogenes in meat products. In: Listeria, Listeriosis and Food Safety. Ryser E. T. and Marth E. H. (Eds.), 3rd edition, CRC Press. Pages: 503-570.
- Pagotto, F. Corneau, N. and Farber, J.M. (2006). Listeria monocytogenes infections. In: Foodborne Infections and Intoxications. Riemann, H.P. and Cliver, D.O. (Eds.), 3rd edition, Academic Press. Pages: 313-340.
- Pagotto, F., King, L-K, Clark, C. Farber, J.M. and the Canadian Public Health Laboratory Network. (2006). Canadian Listeriosis Reference Service. Foodborne Pathog. Dis., 3:132-137.
- ILSI Expert Panel. (2005). Achieving continuous improvement in reductions in foodborne listeriosis - a risk based approach. J. Food Prot., 68:1932-1994.
- Farber, J.M., Daley, E.M., Mackie, M.T. and Limerick, B. (2000). A small outbreak of listeriosis potentially linked to the consumption of imitation crab meat. Lett. Appl. Microbiol., 31:100-104.
- Farber, J.M. and Harwig, J. (1996). The Canadian Position on Listeria monocytogenes in Ready-to-eat Foods. Food Control, 7: 253-258.
- Farber, J.M., Ross, W.H. and Harwig, J. (1996). Health Risk Assessment of Listeria monocytogenes in Canada. Int. J. Food Microbiol., 30:145-156
- Lammerding, A.M. and Farber, J.M. (1994). The Status of Listeria monocytogenes in the Canadian Food Industry. Dairy, Food Environ. Sanit., 14: 146-150.
- Farber, J.M. (1993). Current Research on Listeria monocytogenes in Foods: an Overview. J. Food Prot., 56:640-643.
Major Reported Foodborne Listeriosis Outbreaks:
Table 2: Listeriosis Outbreaks Related to Meat and Poultry Products
|Number of cases (deaths)||Foods||References|
|1987-1989||United Kingdom and Ireland||Invasive||355 (94)||Pâté||McLauchlin et al., 1991; Farber and Peterkin, 2000|
|1990||Australia||Invasive||11(6)||Pâté||Watson and Ott, 1990; Kittson, 1992|
|1992||France||Invasive||279 (85)||Jellied pork tongue||Goulet et al., 1993; Jacquet et al., 1995; Salvat et al., 1995|
|1993||France||Invasive||39 (12)||Pork rillettes
(pâté-like RTE meat)
|Goulet, 1995; Goulet et al., 1998|
|1998-1999||U.S.A.||Invasive||108 (14)||Meat frankfurters||Anonymous, 1998; Anonymous, 1999a; Mead et al., 2006|
|1999-2000||France||Invasive||10 (3)||Rillettes (pâté-like RTE meat)||de Valk et al., 2001; Swaminathan et al., 2007|
|1999-2000||France||Invasive||32 (10)||Jellied pork tongue||Dorozynski, 2000; de Valk et al., 2001; Swaminathan et al., 2007|
|2000||U.S.A.||Invasive||30 (7)||Deli turkey meat||Hurd et al., 2000; Olsen et al., 2005|
|2000||Australia||Non- invasive||31||RTE corned beef and ham||Sim et al., 2002|
|2001||U.S.A.||Non-invasive||16||Precooked sliced turkey||Frye et al., 2002|
|2002||U.S.A.||Invasive||54 (8)||Sliceable turkey deli meats||Anonymous, 2002; Gottlieb et al., 2006|
|2008||Canada||Invasive||57 (22)||RTE deli meats||PHAC, 2008|
Table 3: Listeriosis Outbreaks Related to Dairy Products
|Number of cases (deaths)||Foods||References|
|1983||U.S.A.||Invasive||49 (14)||Pasteurized milk||Fleming et al., 1985|
|1983-1987||Switzer-land||Invasive||122 (31)||Soft cheese||Bille, 1990; Büla et al., 1995; Farber and Peterkin, 1991|
|1985||U.S.A.||Invasive||142 (48)||Mexican-style fresh cheese||Anonymous, 1985; Linnan et al., 1988|
|1989-1990||Denmark||Invasive||26 (6)||Blue mould cheese or hard cheese||Jensen et al., 1994|
|1994||U.S.A.||Invasive||45||Chocolate milk||Proctor et al., 1995; Dalton et al., 1997|
|1995||France||Invasive||37 (11)||Raw milk soft cheese||Goulet et al., 1995; Rocourt et al., 1997; Lundén et al., 2004|
|1997||France||Invasive||14||Soft cheeses||Jacquet et al., 1998|
|1998-1999||Finland||Invasive||25 (6)||Butter made from pasteurized milk||Lyytikäinen et al., 2000|
|2000||Canada (MB)||Invasive||25||Flat whipping cream||Pagotto et al., 2006; Pagotto, 2009|
|2000-2001||U.S.A.||Invasive||13||Mexican-style fresh cheese||Boggs et al., 2001; MacDonald et al., 2005|
|2001||Sweden||Non-invasive||> 120||Fresh cheese made from raw milk in a summer farm||Carrique-Mas et al., 2003; Danielsson-Tham et al., 2004|
|2001||Japan||Non-invasive||38||Washed-type cheese||Makino et al., 2005|
|2001||Belgium||Invasive||2||Frozen ice cream cake||Yde and Genicot, 2004|
|2002||Canada (BC)||Invasive||47||Cheese made from pasteurized milk||Pagotto et al., 2006; Pagotto, 2009|
|Invasive||17||Soft and semi-hard raw milk cheese||Gaulin et al., 2003; Pagotto et al., 2006|
|2002||Canada (BC)||Non-invasive||86||Cheese made from pasteurized milk||Pagotto et al., 2006|
|2003||U.S.A.||Invasive||13 (2)||Mexican-style fresh cheese||Carriedo, 2003; Swaminathan and Gerner-Smidt, 2007|
|2005||Switzer-land||Invasive||10 (3)||Soft cheese||Bille et al., 2006|
|2007||U.S.A.||Invasive||5 (3)||Pasteurized flavoured and non-flavoured milk||Cuming et al., 2008|
|2008||Canada (PQ)||Invasive||38 (2)||Cheeses||MSSS, 2009/MAPAQ, 2009|
Table 4: Listeriosis Outbreaks Related to Fish and Seafood Products
|Number of cases (deaths)||Foods||References|
|1989||U.S.A.||Non-invasive||9 (1)||Shrimp||Riedo et al., 1994|
|1991||Australia (Tasmania)||Non-invasive||4||New Zealand produced smoked mussels||Mitchell, 1991; Misrachi et al., 1991; Brett et al., 1998|
|1992||New Zealand||Invasive||4 (2)||Smoked mussels||Baker et al., 1993; Brett et al., 1998|
|1994-1995||Sweden||Invasive||6 (1)||"Gravad" rainbow trout or cold-smoked rainbow trout||Ericsson et al., 1997|
|1996||Canada||Invasive||2||Imitation crab meat||Farber et al., 2000|
|Un-known||Finland||Non-invasive||5||Cold-smoked rainbow trout||Miettinen et al., 1999|
Table 5: Listeriosis Outbreaks Related to Fruit and Vegetable Products
|Number of cases (deaths)||Foods||References|
|1981||Canada||Invasive||41 (17)||Cole slaw mix||Schlech et al., 1983|
|1997||Italy||Non-invasive||1566||Corn and tuna salad||Aureli et al., 2000|
|1998-1999||Australia||Invasive||6 (5)||Commercially prepared fruit salad||Rooney and Sutherland, 2001; Ozfoodnet, 2006|
Table 6: Listeriosis Outbreaks Related to Other Food Products
|Number of cases (deaths)||Foods||References|
|1993||Italy||Non-invasive||23||Rice salad||Salamina et al., 1996;
Farber and Peterkin, 2000
|2003||United Kingdom||Invasive||5||Prepacked sandwiches||Dawson et al., 2006|
|2009||Australia||unknown||8||Chicken wrap||International Food Safety Authorities Network, 2009|
Use of Food Additives, Processing Aids and/or Post-Process Lethality Treatments for Ready-to-Eat Foods:
RTE foods exposed to the environment after their manufacturing process are at greater risk of becoming contaminated by L. monocytogenes. Recently, new RTE product formulations that incorporate Listeria inhibitors to reduce or eliminate the potential for listerial growth have been developed. Alternatively, post-process lethality treatments can also be used to reduce or eliminate L. monocytogenes in RTE foods. Although voluntary, the use of food additives, processing aids and/or post-processing lethality treatments for L. monocytogenes in RTE foods, alone or in combination, is strongly encouraged for this purpose. It remains the responsibility of the industry to demonstrate its ability and willingness to reduce the potential risks associated with RTE foods. It should, however, be noted that only those permitted for use in Canada can be added and/or applied to RTE foods, as per the Food and Drugs Act and Regulations (Department of Justice Canada, 2008).
i) Food additives and/or processing aids:
The use of Listeria inhibitors (classified either as food additives or processing aids under the Food and Drugs Act and Regulations) is one of various steps in the overall approach to minimize the risks associated with L. monocytogenes in RTE foods. During RTE food production, the correct implementation of GMPs will help to prevent the introduction of microbial pathogens and minimize their potential growth. The function of an antimicrobial treatment is to reduce or totally inhibit the growth of L. monocytogenes. Food producers should be aware that the degree of control in these two areas has a significant impact on the overall safety of their RTE foods. For this reason, the application of any listericidal/listeriostatic treatment that is intended to be used should be validated to ensure its effectiveness and consistency (CAC, 2009a). The scientific literature proposes different antimicrobial treatments for RTE foods which can achieve different levels of L. monocytogenes growth inhibition and/or pathogen reduction and, therefore minimize the risks associated with these types of products. Intense research is on-going to find effective Listeria inhibitors that can provide growth inhibition and/or reduction in RTE foods throughout their shelf-lives. Examples of such inhibitors include potassium lactate, sodium acetate, sodium diacetate and sodium lactate. For practical purposes, a food in which L. monocytogenes does not increase in numbers by 1 log CFU/g during the expected shelf-life under reasonably foreseeable conditions of distribution, storage and use, as determined by a direct plating method (i.e., MFLP-74 or equivalent method), is considered not to support growth of the organism. The additional use of Listeria inhibitors in RTE foods may be evaluated by the Food Directorate, HPFB, Health Canada, if sufficient data is provided. Currently approved food additives that can be used to potentially control the growth of L. monocytogenes in foods are listed in Table 7.
Table 7: Food Additives that May Currently be Used as Class II10 Preservatives in Canada
|Additive||Permitted in or upon||Maximum level of use||Date published in Canada Gazette Part I
(Health Canada, 2009)
|Potassium lactate||Processed cooked meat and poultry products. Note that treated cooked solid-cuts of meat or poultry must contain a minimum protein content of 12 %.||Level consistent with GMP||IMA of November 29, 1997
IMA of January 30, 1999
|Sodium acetate||Flakes of meat; sausages of the type salami, wiener, frankfurter, blood sausage, black pudding, blood pudding, blood and tongue sausage; potted meat; meat pâté; liver paste; liver spread; pâté de foie; meat loaf, meat lunch; luncheon meat; cooked ham; corned beef; cooked meat roll; meat pie; brawn; headcheese; meat spread and unstandardizeda foods containing cooked or cured meat or poultry||Level consistent with GMP||IMA of September 20, 2008|
|Sodium diacetate||Flakes of meat; sausages including fresh uncooked sausage, preserved or cured sausage, salami, wiener, frankfurter, blood sausage, black pudding, blood pudding, blood and tongue sausage; potted meat; meat pâté; liver paste; liver spread; pâté de foie; meat loaf, meat lunch; luncheon meat; corned beef; ham, bacon, meat roll; meat pie; brawn; headcheese, meat spread and unstandardizeda cooked and uncooked foods containing meat, poultry and fish||Up to 0.25 % of the final product weight||IMA of September 20, 2008|
|Sodium diacetate||Prepared and preserved fish products, such as smoked fish||Up to 0.25 % of final product weight||IMA of February 14, 2009|
|Sodium lactate||Processed cooked meat and poultry products. Note that treated cooked solid-cuts of meat or poultry must contain a minimum protein content of 12 %.||Level consistent with GMP||IMA of November 29, 1997
IMA of January 30, 1999
ii) Post-process lethality treatments:
The use of a post-process lethality treatment11 (either classified as "novel" or "non-novel" under the Food and Drugs Act and Regulations) can also be part of an overall approach to minimize the risks associated with L. monocytogenes in RTE foods. Such an intervention step can reduce the levels or inactivate any L. monocytogenes found on the surfaces of the product due to post-processing contamination. Examples of post-process lethality treatments include surface heat pasteurization (by steam, hot water, radiant oven heating or infrared technology) and high-pressure processing. At the present time, a post-process lethality treatment for RTE foods that can achieve a minimum 3-log reduction in numbers of L. monocytogenes is recommended. It is important to note that independent of the effectiveness of the post-process lethality treatment, RTE foods should be manufactured according to Good Manufacturing/Hygienic Practices (Houben and Eckenhausen, 2006; Huang and Sites, 2008). A currently approved post-process lethality treatment that can be used to mitigate the risk of L. monocytogenes in RTE foods is shown in Table 8.
Table 8: Post-process Lethality Treatments for L. monocytogenes that May Currently be Used in Canada
|Foods||Post-processing lethality treatment||Application||References|
|RTE meats and poultry packaged in flexible films||High Hydrostatic Pressure||87 000 PSI (600 MPa) for 3 min||Health Canada (2007b)|
In conclusion, the use of a combination of methods, including an antimicrobial treatment and/or a post-process lethality treatment, is recommended to produce a safer RTE product. It should be noted that if both strategies are used in conjunction, a synergistic effect could also potentially be achieved.
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Anonymous. (1985). Epidemiologic notes and reports Listeriosis outbreak associated with Mexican-style cheese - California. CDC-MMWR, 34: 357-359. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/00000562.htm
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Anonymous. (1999b). Listeria cases linked to pâté. Westchester County Department of Health. Available at: http://www.westchestergov.com/health/PR991230.htm (Accessed on November 16, 2009).
Anonymous. (2002). Public Health Dispatch: Outbreak of listeriosis -- Northeastern United States, 2002. CDC-MMWR, 51: 950-951. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5142a3.htm
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Boggs, J.D., Whitwam, R.E., Hale, L.M., Briscoe, R.P., Kahn, S.E., MacCormack, J.N., Maillard, J-M., Grayson, S.C., Sigmon, K.S., Reardon, J.W., Saah, J.R. and EIS officers, CDC. (2001). Outbreak of listeriosis associated with homemade Mexican-style cheese - North Carolina, October 2000 - January 2001. CDC-MMWR, 50: 560-562. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5026a3.htm and in J. Am. Med. Asso., 286(6): 664-665.
Brett, M.S.Y., Short, P. and McLauchlin, J. (1998). A small outbreak of listeriosis associated with smoked mussels. Int. J. Food Microbiol., 43: 223-229.
Büla, C., Bille, J. and Glauser, M.P. (1995). An epidemic of food-borne listeriosis in western Switzerland: Description of 57 cases involving adults. Clin. Infect. Dis., 20: 66-72.
CFIA (Canadian Food Inspection Agency). (2009). Personal communication.
Carriedo, G. (2003). Mexican cheese may cause listeriosis. News release from the city of Laredo Health Department. Available at: http://www.ci.laredo.tx.us/health/News/08-20-03MexicanCheese/Mexican%20Cheese.htm (Accessed on November 16, 2009).
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Dalton, C. B., Austin, C., Sobel, J., Hayes, P.S., Bibb, W. F., Graves, L.M., Swaminathan, B., Proctor, M.E. and Griffin, P.M. (1997). An outbreak of gastroenteritis and fever due to Listeria monocytogenes in milk. N. Engl. J. Med., 336: 100-105.
D'Amico, D.J. and Donnelly, C.W. (2008). Enhanced detection of Listeria spp. in farmstead cheese processing environments through dual primary enrichment, PCR, and molecular subtyping. J. Food Prot., 71: 2239-2248.
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1 The term GMPs in the text is used as a generic term and includes all key conditions and control measures necessary for manufacturers to ensure the safety and the suitability of food during manufacturing.
2 For the purposes of this document, this includes both food contact and non-food contact surfaces.
3 For the purposes of this document, this includes L. monocytogenes.
1 Laboratory Procedure (MFLP) 74 will soon be updated with the intent of increasing its limit of detection. A 1:5 dilution will be required.
5 RTE fresh-cut fruits and vegetables are subject to the provisions of this policy, i.e., raw fresh fruit and vegetables that have been either washed and peeled, either sliced, chopped or shredded prior to being packaged for sale and are intended to be consumed raw and not for further processing or cooking. Examples include: shredded bagged lettuce, coleslaw, fresh-cut melons or fruit salad.
6 Non RTE fresh-cut fruits and vegetables are not subject to the provisions of this policy, i.e., raw fresh fruit and vegetables that have been either washed, peeled, sliced, chopped or shredded prior to being packaged for sale with cooking instructions on the package (e.g., mixed fresh-cut vegetables intended as pizza dressing or intended for use in preparing soup), as well as raw whole fresh fruits and vegetables, i.e., whole fresh fruit and vegetables that have only been trimmed, cleaned, brushed, washed, graded, packaged or otherwise prepared for human consumption (e.g., fresh herbs, whole or trimmed fruit or vegetables, whole leaf vegetables and berries).
7 Exception: For example sushi, which may or may not contain raw fish, is considered a RTE food and hence is subject to the provisions of this policy.
8 For example, canned foods and cook-in-bag products which achieve a minimum 5-log reduction in numbers of L. monocytogenes.
9 For example, it has been demonstrated that shredded/sliced carrots may have an anti-Listeria activity (Beuchat and Brackett, 1990; Nguyen-the and Lund, 1991).
10 A preservative acts to prolong the shelf-life of foods by protecting against deterioration caused by microorganisms or oxidation. A Class II preservative is considered to be an antibacterial agent (Health Canada, 2007a).
11 The use of novel technologies for post-process lethality treatments could be subjected to a comprehensive assessment by the Food Directorate, Health Canada according to the Guidelines for the Safety Assessment of Novel Foods (Health Canada, 2006).
For "non-novel" post-process lethality treatments, it is highly recommended that the microbiological safety and efficacy of these new or improved food processing and handling techniques proposed by the food industry (e.g., steam pasteurization, hot water treatment, radiant oven heating, infrared heating) be assessed by the BMH, Health Canada.
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