Guidance Document on Ready-to-Eat Smoked Fish and Multi-Ingredient Products Containing Smoked Fish

1. Purpose and scope

This document is intended to provide guidance to food safety regulators and food manufacturers to mitigate the potential microbiological risks associated with ready-to-eat smoked fish^Footnote a and multi-ingredient products containing smoked fish. This is due to the potential contamination and/or growth of certain foodborne pathogens of concern i.e., Clostridium botulinum and Listeria monocytogenes. This document also provides guidance on inactivation methods for parasites that may contaminate the fish tissue. The specific development of processing parameters is to be established by the manufacturer in order to produce a safe product. Regulatory agencies such as the Canadian Food Inspection Agency (CFIA) and/or provincial/territorial governments may also have specific requirements (e.g., additional controls over processing parameters), that would need to be met.

On April 4, 2017, a draft version of this guidance document was made available for consultation to the larger stakeholder community, via the Health Canada website. Comments were accepted until June 2, 2017. This final document includes changes incorporated as a result of the comments received.  

2. Definitions

In the context of this guidance document, the following definitions apply:

• 2.1  Cold smoking: "Is a process of treating fish with smoke using a time/temperature combination that will not cause significant coagulation of the proteins in the fish flesh but that will cause some reduction of the water activity" (CAC, 2013).
• 2.2  Commercially sterile: "The condition obtained in a food that has been processed by the application of heat, alone or in combination with other treatments, to render the food free from viable forms of microorganisms, including spores, capable of growing in the food at temperatures at which the food is designed normally to be held during distribution and storage" (Government of Canada, 2018a).
• 2.3  Durable life: "The period, commencing on the day on which a prepackaged product is packaged for retail sale, during which the product, when it is stored under conditions appropriate to that product, will retain, without any appreciable deterioration, its normal wholesomeness, palatability, nutritional value and any other qualities claimed for it by the manufacturer" (Government of Canada, 2018a).
• 2.4  Durable life date: "The date on which the durable life of a prepackaged product ends" (Government of Canada, 2018a).
• 2.5  Fish: Fish refers only to finfish for the purpose of this document. Shellfish, crustaceans and other marine animals are not included under the definition of fish in this document (modification of CFIA, 2015).
• 2.6  Frozen: "Congealed with cold" (Biology online, 2005).
• 2.7  Hermetically sealed container: "A container designed and intended to be secure against the entry of microorganisms, including spores" (Government of Canada, 2018a).
• 2.8  Hot smoking: "Is a process in which fish is smoked at an appropriate combination of temperature and time sufficient to cause the complete coagulation of the proteins in the fish flesh" (CAC, 2013).
• 2.9  Low-acid food: "A food, other than an alcoholic beverage,  where any component of the food has a pH greater than 4.6 and a water activity greater than 0.85" (Government of Canada, 2018a).
• 2.10  Multi-ingredient products containing smoked fish: Examples of such products (which could be either homogeneous or heterogeneous) include:  mousses, pâtés, dips, soups, quiches, stuffed olives, sandwiches, all of which contain smoked fish. Smoked fish in oil would also be considered a multi-ingredient product containing smoked fish.
• 2.11  Multiple hurdle approach: Refers to a combination of interventions applied to food aimed at preserving its safety and quality throughout its shelf-life.
• 2.12  pH: "A measure of acidity and alkalinity of a solution that is a number on a scale on which a value of 7 represents neutrality and lower numbers indicate increasing acidity and higher numbers increasing alkalinity and on which each unit of change represents a tenfold change in acidity or alkalinity and that is the negative logarithm of the effective hydrogen-ion concentration or hydrogen-ion activity in gram equivalents per litre of the solution" (Merriam-Webster Dictionary, 2018).
• 2.13  Proteolytic: Producing the hydrolysis of proteins, i.e., "capable of digesting meat particles, casein, and coagulated egg albumin" causing the production of off-odors (Hatheway, 1993; Lund and Peck, 2000).
• 2.14  Ready-to-eat foods: "Ready-to-eat foods are those not requiring any further preparation before consumption, except perhaps washing/rinsing, thawing or warming" (Health Canada, 2011).
• 2.15  Refrigeration: "Exposure to a temperature of 4^oC or less but does not mean frozen" (Government of Canada, 2018a).
• 2.16  Shipping container: "A receptacle, package or wrapper in which containers of food are placed for transportation" (Government of Canada, 2018a).
• 2.17  Spore: "A primitive usually unicellular often environmentally resistant dormant or reproductive body produced by plants, fungi, and some microorganisms and capable of development into a new individual either directly or after fusion with another spore" (Merriam-Webster Dictionary, 2018).
• 2.18  Water activity (a_w): "The ratio of the water vapour pressure of a food to the vapour pressure of pure water, at the same temperature and pressure" (Government of Canada, 2018a).

3. Background

Health Canada's Bureau of Microbial Hazards has updated its position on ready-to-eat smoked fish and multi-ingredient products containing smoked fish. This guidance (also refer to Appendix A) is based on Sections 4 and 7 of the Food and Drugs Act (Government of Canada, 2018b), Sections B.21.025 and B.27.002 of the Food and Drug Regulations (Government of Canada, 2018a). It also includes guidance for (refrigerated) smoked fish not covered under B.21.025, as well as for multi-ingredient products containing smoked fish under B.27.002.

C. botulinum, L. monocytogenes and certain parasites can be found in ready-to-eat smoked fish and multi-ingredient products containing smoked fish, due to the common prevalence of these microorganisms in fish (raw material) and the processing conditions used to make these products (Dodds, 1993; FAO, 1999; USFDA, 2011). As these pathogens can be present in ready-to-eat smoked fish and ready-to-eat multi-ingredient products containing smoked fish, it is important for food manufacturers and food safety regulators to apply measures to mitigate the microbiological risks associated with these products.

4. Relevant food regulations

4.1 Ready-to-eat smoked fish

Section B.21.025 of the Food and Drug Regulations (Government of Canada, 2018a) states:

"No person shall sell marine and fresh water animals, or marine and fresh water animal products, that are packed in a container that has been sealed to exclude air and that are smoked or to which liquid smoke flavour or liquid smoke flavour concentrate has been added unless:

• a) the container has been heat-processed after sealing at a temperature and for a time sufficient to destroy all spores of the species Clostridium botulinum; or
• b) the contents of the container contain not less than 9% salt, as determined by official method FO-38, Determination of Salt in Smoked Fish, dated March 15, 1985; or
• c) the contents of the container are customarily cooked before eating; or
• d) the contents of the container are frozen and the principal display panel of the label of the container carries the statement "Keep Frozen Prior to Use" in the same size type used for the common name of the contents of the container."

Furthermore, Section B.27.002 of the Food and Drug Regulations (Government of Canada, 2018a) also needs to be considered in parallel to B.21.025, when applicable. Section B.27.002 states that:

• "(1) No person shall sell a low-acid food packaged in a hermetically sealed container unless the food is commercially sterile.
• (2) Subsection (1) does not apply in respect of a low-acid food packaged in a hermetically sealed container where
  • (a) the low-acid food is kept under refrigeration and the statement "Keep Refrigerated" and "Garder au froid" is carried on the principal display panel of the label of its container, as well as on the label of its shipping container; or 
  • (b) the low-acid food is kept frozen and the statement "Keep Frozen" and "Garder congelé" is carried on the principal display panel of the label of its container, as well as on the label of its shipping container."

4.2 Ready-to-eat multi-ingredient products containing smoked fish

Some ready-to-eat multi-ingredient products containing smoked fish may fall under the definition of low-acid foods packed in hermetically-sealed containers and therefore have to meet the requirements of Section B.27.002 of the Food and Drug Regulations (Government of Canada, 2018a). When not processed to commercial sterility, and if not kept frozen at all times, these ready-to-eat multi-ingredient products containing smoked fish should be kept under refrigeration, be labelled as such (i.e., with the statement "Keep Refrigerated" and "Garder au froid^Footnote b"), and carry a stated shelf-life (e.g., durable life date shown as "best before" date on the package) as per Sections B.27.002 and B.01.007 of the Food and Drug Regulations, respectively (Government of Canada, 2018a). Knowledge concerning the interaction of safety factors in products containing smoked fish may permit refrigerated storage of these products, provided control over microbiological hazards is achieved. Safety factors include, but are not limited to, heat processes, reduced pH and/or reduced water activity.

5. Control of pathogens

The pathogens of concern discussed in this guidance document i.e., C. botulinum, L. monocytogenes and parasites, are those whose presence is to be taken into consideration  in the product due to the common prevalence of these microorganisms in fish (raw material) or the processing conditions that could lead to contamination of these foods (Dodds, 1993; FAO, 1999; USFDA, 2011). The guidance presented herein describes the parameters that should be met in the finished product that will prevent the growth and toxin production by C. botulinum, provides criteria to minimize the potential for contamination and/or growth of L. monocytogenes and provides strategies to inactivate parasites that may be present.

5.1 Clostridium botulinum

Fish is most likely to be contaminated with non-proteolytic strains of C. botulinum type E (Dodds, 1993), but smoked fish, and especially multi-ingredient products containing smoked fish, may be contaminated with both proteolytic and non-proteolytic strains of C. botulinum, depending on the ingredients that are used in the formulation of the product. Therefore, the risk of botulism intoxication resulting from growth and toxin production of all possible strains of C. botulinum must be controlled (Eklund, 1993).

Inhibition of growth of the non-proteolytic strains of C. botulinum (which includes type E) is accomplished by any of the following criteria: storage temperature to be kept at less than 3°C, pH less than 5.0 or water activity less than 0.97. Inhibition of growth of proteolytic strains of C. botulinum is accomplished by any of the following criteria: storage temperature to be kept at less than 10°C, pH less than 4.6 or water activity less than 0.94 (Austin, 2001; Johnson, 2007).

5.1.1 Ready-to-eat smoked fish

For smoked fish, Section B.21.025 of the Food and Drug Regulations (Government of Canada, 2018a) specifically delineates control measures for C. botulinum, and specifically applies to smoked fish that is "packaged sealed to exclude air", as mentioned in part 4.1 of this document. "Packaged sealed to exclude air" is defined as a package where the product (i.e., smoked fish) is placed in and wrapped with packaging material that has an oxygen permeability of less than 2 000 cc/m²/24h^Footnote c at 24^oC and 1 atm. Therefore, smoked fish placed and wrapped in a film having an oxygen permeability equal to or greater than 2 000 cc/m²/24h^Footnote c at 24^oC and 1 atm is not considered to be packaged sealed to exclude air and is therefore considered to be packaged aerobically. Smoked fish sold in the aerobic packaging described above are not subject to the provisions of B.21.025, and thus may be sold in the refrigerated state, provided the following additional conditions are met:

• the smoked fish is continuously refrigerated and held at a temperature of 4^oC or less and is labelled as such (i.e., with the statement "Keep Refrigerated" and "Garder au froid^Footnote b "); and
• the smoked fish has a refrigerated shelf-life of ≤ 14 days from the date at which it was initially packaged and is labelled with a durable life date (best- before-date); and
• the smoked fish is placed and wrapped in a single layer of film, which has an oxygen permeability equal to or greater than 2 000 cc/m²/24h^Footnote c at 24^oC and 1 atm; and
• the processors and/or retailers using such films keep records of the type of films used and their permeability^Footnote d.

The inhibition of the growth and toxin production by C. botulinum in ready-to-eat smoked fish is accomplished using a multiple hurdle approach (i.e., ≤ 14-day shelf-life and strict refrigerated storage temperature control). Furthermore, aerobic spoilage microorganisms are expected to grow under oxygen permeable films. Their growth may result in signs of spoilage noticeable to the consumers prior to the potential growth and toxin production by C. botulinum. Care should be taken to avoid stacking the packages in a manner that will inhibit the oxygen permeability (i.e., full contact of adjacent packages or labels over large surface areas of the films should be avoided).

5.1.2 Ready-to-eat multi-ingredient products containing smoked fish

It is the responsibility of industry to produce safe food, in accordance with Section 4 of the Food and Drugs Act (Government of Canada, 2018b).

In order to control C. botulinum, such products should be kept refrigerated at 4^oC or less and be labelled with a statement "Keep Refrigerated" and "Garder au froid^{Footnote b}"). Each component in a multi-ingredient product containing smoked fish should have:

• a pH^Footnote e of less than 5.0; or
• a water activity^Footnote e of less than 0.97^Footnote f; or
• received a thermal treatment resulting in a 6D logarithmic reduction of spores of non-proteolytic strains of C. botulinum (e.g., 90^oC, 10 min) (USFDA, 2011)

The use of the multiple hurdle approach will result in a food where the control of C. botulinum is achieved. Strict refrigeration temperatures (i.e., 4°C or less), in combination with the pH, water activity or thermal treatment parameters listed above, will control the growth and toxin production of proteolytic and non-proteolytic strains of C. botulinum. These products must be stored at refrigeration temperatures at all times in order to control the growth of proteolytic strains of C. botulinum.

5.2 Listeria monocytogenes

Listeria monocytogenes is considered to be a microorganism likely to occur in the smoked fish processing environment and consequently can also be found on the finished product. L. monocytogenes has been frequently isolated from smoked fish (FAO, 1999; FSA, 2008; Uyttendaele et al., 2009; Kovačević et al., 2012; Lambertz et al., 2012; González et al., 2013).

L. monocytogenes can grow aerobically or anaerobically. Important characteristics of this microorganism are its ability to grow at temperatures of -0.4 to 45^oC, pH values of 4.4 or greater and water activities of 0.92 or higher (ICMSF, 1996). In addition, Health Canada's Policy on Listeria monocytogenes in ready-to-eat foods (Health Canada, 2011) highlights a combination of factors in which growth of L. monocytogenes can/cannot occur in ready-to-eat foods (also refer to Appendix A).

5.2.1 Ready-to-eat smoked fish and multi-ingredient products containing smoked fish

Ready-to-eat smoked fish and multi-ingredient products containing smoked fish should comply with Health Canada's Policy on Listeria monocytogenes in ready-to-eat foods (Health Canada, 2011). The 2011 Health Canada's Policy on Listeria monocytogenes in ready-to-eat foods promotes a global approach to Listeria control (e.g., uses a combination of inspection, environmental sampling and finished product testing to verify the control of L. monocytogenes in ready-to-eat foods). As such, processors should strive for negative results on food contact surfaces as well as finished products and respond to each positive sample with appropriate corrective actions in a timely manner.

Cold-smoked fish: L. monocytogenes has been found to survive the cold-smoking process since the temperatures used during cold smoking do not result in a reduction in the number of L. monocytogenes (Eklund et al., 1995). Therefore, processors must implement strict control measures to address this hazard during processing. These control measures include a stringent sanitation and strict employee hygiene plan, and the implementation of overall good manufacturing practices. To verify the effectiveness of these controls, environmental sampling to detect Listeria spp. and finished product testing to detect L. monocytogenes should be used as a verification procedure in a processor's food safety plan (Health Canada, 2011).

Hot-smoked fish: Temperatures reached during the hot-smoking process of fish will result in some reduction of L. monocytogenes, if present. However, post-processing contamination of hot-smoked fish can occur and L. monocytogenes may grow on hot smoked fish at a rate as fast as, or faster than what has been observed on cold-smoked fish due to the decreased competition from other microorganisms (USFDA, 2011). Good manufacturing practices and a robust food safety plan are important for preventing and detecting post-processing contamination of hot-smoked fish by L. monocytogenes (Health Canada, 2011).

In addition, although voluntary, the use of food additives^Footnote g, processing aids and/or post-lethality treatments can be used for the control of L. monocytogenes in ready-to-eat smoked fish and multi-ingredient products containing smoked fish.

5.3 Parasites

Some helminth parasites, if present at larval stages in smoked fish, can pose a risk to consumers provided that no other treatment to eliminate them is used. Parasites of concern in smoked fish products include nematodes (e.g., Anisakis spp. and Pseudoterranova spp.), cestodes (e.g., Diphyllobothrium spp.) and trematodes (e.g., Clonorchis spp., and Opisthorchis spp.) (USFDA, 2011).

While the hot-smoking process is generally considered sufficient to kill parasites (CAC, 2013), many parasites can survive the cold-smoking process (Gardiner, 1990). Parasites in fish can be killed by:

• Freezing the fish, pre- or post- smoking, at -35^oC or below for a period of not less than 15 h or at -20^oC for a period of not less than 168 h (7 days)  (CAC, 2013); or
• Cooking the fish to a minimum internal temperature of 70^oC (e.g., some hot-smoking processes) and holding the product at that temperature for not less than 1 min (Vidaček et al., 2010).

6. References

• Austin, J. W. (2001). "Clostridium botulinum". In: Food Microbiology: Fundamentals and Frontiers, 2^nd edition (ed., M.P. Doyle , L.R. Beauchat and T.J. Montville.),  ASM Press, Washington, D.C. pp. 329-349.
• Biology online. (2005). (Accessed October 26, 2016).
• CAC (Codex Alimentarius Commission). (2009). Guidelines on the Application of General Principles of Food Hygiene to the Control of Listeria monocytogenes in Foods - Annex II Microbiological Criteria for Listeria monocytogenes in Ready-to-Eat Foods (Accessed on October 26, 2016).
• CAC (Codex Alimentarius Commission). (2013). Standard for Smoked Fish, Smoke-Flavoured Fish and Smoke-dried Fish. Codex Standard: 311-2013 (Accessed on October 26, 2016).
• CFIA (Canadian Food Inspection Agency). (2015). Fish Products Inspection Manual – Definitions (Accessed on October 26, 2016).
• Dodds, K. L. (1993). "Clostridium botulinum in Foods". In: Clostridium botulinum - Ecology and control in foods, (ed., A.H.W. Hauschild and K.L. Dodds), Marcel Dekker, Inc., New York, pp. 53-68.
• Eklund, M. W. (1993). "Control in fishery products". In: Clostridium botulinum Ecology and control in foods, (ed., A.H.W. Hauschild and K.L. Dodds), Marcel Dekker, Inc., New York, DC. pp. 209-232.
• Eklund, M. W., Poysky F.T., Paranjpye, R.N., Lashbrook, L.C., Peterson, M.E. and G.A. Pelroy. (1995). Incidence and sources of Listeria monocytogenes in cold smoked fishery products and processing plants. Journal of Food Protection, 58(5):502-508.
• FAO (Food and Agriculture Organization of the United Nations). (1999). Report of the FAO expert consultation on the trade impact of Listeria in fish products. Fisheries Report No. 604. (Accessed on October 26, 2016).
• FSA (Food Standards Agency). (2008). A microbiological survey of retail smoked fish with particular reference to the presence of Listeria monocytogenes. Project Code: B18022.
• Gardiner, M. A. (1990). Survival of Anisakis in cold smoked salmon. Canadian Institute of Food Science and Technology Journal, 23:143-144.
• González, D., Vitas, A.I., Díez-Leturia, M. and I. García-Jalón. (2013). Listeria monocytogenes and ready-to-eat seafood in Spain: Study of prevalence and temperatures at retail. Food Microbiology, 36: 374-378.
• Government of Canada. (2018a). Food and Drug Regulations (Accessed on April 30, 2018).
• Government of Canada. (2018b). Food and Drugs Act (Accessed on April 30, 2018).
• Hatheway, C.L. (1993). "Clostridium botulinum and other clostridia that produce botulinum neurotoxin". In: Clostridium botulinum - Ecology and control in foods, (ed., A.H.W. Hauschild and K.L. Dodds), Marcel Dekker, Inc., New York, pp. 3-20.
• Health Canada. (2011). Policy on Listeria monocytogenes in ready-to-eat foods (Accessed on October 26, 2016).
• Health Canada. (2012). 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) (Accessed on October 26, 2016).
• Health Canada. (2016). List of Permitted Preservatives (Accessed on October 26, 2016).
• Health Canada. (2018). The Compendium of Analytical Methods (Accessed on April 30, 2018).
• ICMSF (International Commission on Microbiological Specifications for Foods). (1996). Listeria monocytogenes. In: Microorganisms in Foods 5. Characteristics of Microbial Pathogens, Blackie Academic & Professional, London (ISBN 0412 47350 X), pp. 141-182.
• Johnson, E. A. (2007). "Clostridium botulinum". In: Food Microbiology: Fundamentals and Frontiers, 3^rd edition (ed., M.P. Doyle and L.R. Beauchat), ASM Press, Washington, D.C. pp. 401-421.
• Kovačević, J., McIntyre, L. F., Henderson, S. B. and T. Kosatsky. (2012). Occurrence and distribution of Listeria species in facilities producing ready-to-eat foods in British Columbia, Canada. Journal of Food Protection, 75(2): 216-224.
• Lambertz, S. T., Nilsson, C, Brådenmark, A., Sylvén, S., Johansson, A., Jansson, L.M. and M. Lindblad. (2012). Prevalence and level of Listeria monocytogenes in ready-to-eat foods in Sweden 2010. International Journal of Food Microbiology, 160: 24-31.
• Lund, B. M. and M.W. Peck. (2000). "Clostridium botulinum". In: The Microbiological Safety and Quality of Food – Volume II, (ed., B.M. Lund, T. C. Baird-Parker and G.W. Gould), Aspen Publishers, Inc., Gaithersburg, Maryland, pp. 1057-1109.
• Merriam-Webster Dictionary. (2018). (Accessed on April 30, 2018).
• USFDA (United States Food and Drug Administration). (2011). Fish and Fishery Products Hazards and Controls Guidance, 4^th edition. pp. 245-291; pp. 315-330; pp. 417-437 (Accessed on October 26, 2016).
• Uyttendaele, M., Busschaert, P., Valero, A., Geeraerd, A. H., Vermeulen, A., Jacxsens, L., Goh, K. K., De Loy, A, Van Impe, J. F. and F. Devlieghere. (2009). Prevalence and challenge tests of Listeria monocytogenes in Belgian produced and retailed mayonnaise-based deli-salads, cooked meat products and smoked fish between 2005 and 2007. International Journal of Food Microbiology, 133: 94-104.
• Vidaček, S., De Las Heras, C., Solas, M.T., Mendizábal, A., Rodriguez-Mahillo, A.I. and M. Tejada. (2010). Antigenicity and viability of Anisakis larvae infesting hake heated at different time-temperature conditions.  Journal of Food Protection, 73:62-68.

Appendix A: Summary of the control for pathogens in ready-to-eat smoked fish and multi-ingredient products containing smoked fish

Inactivation of parasites:

• Freezing:  ≤ -35^oC for ≥ 15 hours or ≤ -20^oC for ≥ 7 days (e.g., pre- or post-smoking)
• Heating: ≥ 70^oC for ≥ 1 min  (e.g., hot smoking)

Prevention of the growth and toxin production by C. botulinum

1) Smoked Fish (B.21.025 and/or B.27 of the Food and Drug Regulations)

• Frozen until use
• Refrigeration (≤ 4^oC) and shelf-life ≤ 14 days with packaging of an oxygen transmission rate ≥ 2000 cc/m²/24h^Footnote c at 24^oC, 1 atm
• Room temperature, if commercially sterile
• Room temperature, if all components have water activities ≤ 0.85

2) Multi-ingredient foods containing smoked fish (B.27 of the Food and Drug Regulations)

• Frozen until use
• Refrigeration (≤ 4^oC) and pH of all components < 5.0
• Refrigeration (≤ 4^oC) and water activity of all components < 0.97
• Refrigeration (≤ 4^oC) and 6D logarithmic reduction of spores of non-proteolytic strains of C. botulinum (e.g., 90^oC for 10 min) of all components
• Room temperature, if commercially sterile
• Room temperature, if all components have water activities ≤ 0.85

Minimize contamination and/or growth of L. monocytogenes
Coverage of the Policy on Listeria monocytogenes in ready-to-eat foods (2011)

• Environmental sampling plan should be established
• Compliance criteria  should be met:
  • Action level (Category 1^Footnote h): Detected in 125 g for ready-to-eat food in which growth of L. monocytogenes can occur
  • Action level (Category 2A^Footnote i or 2B^Footnote j): > 100 CFU/g^Footnote k for ready-to-eat foods in which growth of L. monocytogenes cannot occur or is limited

Labelling requirements, if applicable (B.01.007 of the Food and Drug Regulations)

• Durable life date
• Instructions for the proper storage of the prepackaged product