Guidance on Mitigating the Health Risk Associated with Clostridium botulinum in Plant and Mushroom Products Stored in Oil

1.  Purpose and scope

This document is intended to provide guidance to food safety regulators, manufacturers and importers with respect to the control of C. botulinum in plant and mushroom products stored in oil or infusing oils. This guidance document applies to any plant and mushroom product that has been covered in oil, which can be found in a sealed package, displayed for sale at the retail level. Plant products include fresh, brined, roasted, dehydrated and re-hydrated vegetable and fruit matter, herbs and spices.

Food safety enforcement bodies at the federal, provincial and territorial level may use this guidance document as a reference to assess compliance with general requirements of food safety legislation or regulations, in particular, compliance with Sections 4 and 7 of the Food and Drugs Act (Government of Canada, 2018a).

On May 29, 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 July 28, 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 Anaerobic organism:

An organism that does not require oxygen for growth and metabolism" (Biology online, 2008).

2.2 Commercially sterile:

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, 2018b).

2.3 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, 2018b).

2.4 Multiple hurdle approach:

Refers to a combination of interventions applied to food aimed at preserving its safety and quality throughout its shelf-life.

2.5 Organoleptic:

Any sensory properties of a product, involving taste, colour, odour and texture.

2.6 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).

2.7 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).

2.8 Refrigerated:

Exposure to a temperature of 4°C or less, but does not mean frozen (Government of Canada, 2018b).

2.9 Hermetically sealed container:

Container designed and intended to be secure against the entry of microorganisms, including spores (Government of Canada, 2018b).

2.10 Water activity (a_w ):

Ratio of the partial vapour pressure of water of the food to that of pure water at the same temperature and pressure (Government of Canada, 2018b).

3. Roles and responsibilities

3.1 Industry

It is the industry’s role and responsibility to comply with all applicable legislative and regulatory requirements which include Sections 4 and 7 of the Food and Drugs Act (Government of Canada, 2018a) and to develop and implement good manufacturing practices and controls that are conducive to the production of safe plant and mushroom products stored in oil.

3.2 Government

Health Canada has a responsibility to identify the nature and assess the level of risk associated with the consumption of contaminated food products and develop food safety standards and guidance documents to help minimize the risk of foodborne illnesses. It is the role of the Canadian Food Inspection Agency (CFIA) and provincial/territorial governments to oversee the food industry to ensure that it meets its food safety responsibilities, including the application of effective and timely management strategies appropriate to the risk, when required. The role of the Public Health Agency of Canada (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 foodborne illness outbreaks. PHAC also plays an active role in food surveillance across the country, e.g., FoodNet, a multi-partner program designed to detect changes in trends in human enteric disease and in levels of pathogen exposure from food, animal and water sources in Canada.

3.3 Consumers

In addition to government agencies and food industries working diligently at minimizing the exposure to pathogens, consumers also have an important role to play. That role calls for Canadians to learn and adopt safe food handling, responsible food selection and safe preparation practices (Health Canada, 2008; Health Canada, 2013). To this end, Health Canada and other regulatory authorities develop science-based educational material to inform consumers about the hazards associated with foods, and how to minimize the risks associated with foodborne disease.

4. Background

Various fresh, dried or dehydrated fruits, vegetables, mushrooms, herbs and spices have historically been stored in oil to extend their shelf-life and/or flavour the oil. Products include sun-dried tomatoes, lupini beans, hot peppers, mushrooms, artichoke hearts, olives, garlic, onion and spices.

Plant and mushroom products stored in oil pose a safety concern, especially since information about the manufacturing process or how potential hazards have been addressed and prevented is not readily available. In addition to the manufacturing process for these products, insufficient information on labels (for example, the lack of “keep refrigerated”) could lead to safety issues.

Storage requirements on the label may be inadequate or fail to notify the consumer if the plant or mushroom products stored in oil should be refrigerated. Depending on the processing of the product, the storage conditions vary (see Appendix 1 for more details about refrigeration). In addition, some types of products that require refrigeration during storage but appear to be shelf-stable to the consumer, may be manufactured using traditional shelf-stable recipes which have been modified (e.g., reducing salt levels) without due consideration for the food safety risks. The manufacturer may have assumed that refrigeration alone was a sufficient barrier to compensate for a change in formulation, but has not assessed the effects of temperature abuse or conducted the appropriate microbiological shelf-life studies.

Botulism cases caused by garlic and other products stored in oil, such as eggplants and mushrooms, have increased the concern in recent years over the safety of plant and mushroom products stored in oil. Some of the outbreaks attributed to these foods are listed in Table 1.

Due to the nature of their use, it is possible that plant and mushroom products stored in oil could be held at room temperature for extended periods of time. While preservation steps such as fermentation, acidification, drying, adequate heating and refrigeration are used to mitigate the risks of foodborne illness associated with these products, some vegetable and mushroom products stored in oil are not prepared, handled or stored properly and thus may present a greater hazard to the consumer.

Following the 1985 botulism garlic-in-oil outbreak in North America, the United States Food and Drug Administration (U.S. FDA) took steps to prevent future outbreaks by requiring that, in addition to refrigeration, microbial inhibitors or acidifying agents be added to these products (Morse et al., 1990). The outbreak (Table 1) prompted Health Canada to seek voluntary industry compliance with incorporation of a microbial hurdle approach in addition to refrigeration for garlic-in-oil products to control the growth of C. botulinum.

To mitigate the risk of foodborne illness associated with the consumption of plant and mushroom products stored in oil, Health Canada developed a guideline for the manufacturing of plant and mushroom products in 1997. This guidance document provides greater clarity to the microbial hazards being controlled and the processing criteria necessary to control these hazards.

5. Microorganisms of concern

Outbreaks involving fresh fruits and vegetables have shown that many different species of pathogenic microorganisms may be present that could result in foodborne illness. However, the processing and storage conditions for plant and mushroom products stored in oil have resulted in foodborne outbreaks related to only one major pathogen, Clostridium botulinum.

5.1  Clostridium botulinum

Clostridium botulinum has been linked to reported foodborne illness outbreaks associated with plant and mushroom products stored in oil (Table 1). The oil surrounding the plant and mushroom product creates an anaerobic environment suitable for the growth of C. botulinum. Foodborne botulism is caused by ingestion of food contaminated with pre-formed botulinum neurotoxin, usually type A, B, E or F (Austin, 2001; Johnson, 2007) and is a descending, symmetrical, flaccid paralysis. The first signs may include gastrointestinal disturbances (e.g., vomiting, diarrhoea and nausea), followed by ocular effects (e.g., droopy eyelids, sluggish response of pupils to light, blurred and double vision) to flaccid neuromuscular paralysis (e.g., difficulty in speech, swallowing and breathing). Respiratory failure often results in death within 3-5 days if left untreated (Sugiyama, 1990). The incubation period for botulism is approximately 12 to 36 hours, depending on the amount of toxin ingested.

C. botulinum is a Gram-positive, rod-shaped soil bacterium that is ubiquitous in the environment (Austin, 2001; Parkinson and Ito, 2007). Strategies to inhibit the growth of C. botulinum include controlling the pH and/or a_w conditions in the food. However, in foods intended to be stored at room temperature, it is necessary to heat the food at a temperature and time that would ensure the destruction of all vegetative cells and spores of C. botulinum (i.e., process to achieve commercial sterility). One such process is called pressure canning/retorting^{Footnote 1} and is applied to low-acid canned foods.

There are seven serotypes of C. botulinum. However, only groups I and II cause human disease and are of concern in these products (Hatheway, 1993; Austin, 2001), see Table 2. Spores of Group I, or proteolytic strains of C. botulinum can germinate and grow in conditions where the pH is ≥ 4.6 and the a_w is ≥ 0.94, but does not grow at refrigeration temperatures (≤4°C) (i.e., minimum temperature of growth is 10°C). Spores of Group II, or non-proteolytic strains of C. botulinum can germinate and grow in conditions where the pH is ≥ 5.0 and the a_w is ≥ 0.97, and can grow slowly at refrigeration temperatures (i.e., minimum growth temperature is 3°C) (Austin, 2001). 

The U.S. FDA estimated that as few as 1-5 spores of proteolytic C. botulinum, producing type A or B toxins may have grown and produced toxin in the garlic-in-oil product involved in the 1985 outbreak (Solomon and Kautter, 1988). Botulinum neurotoxin was detected after 75 days in the product stored at room temperature, with the product remaining organoleptically acceptable. In Canada, a total of 36 people were diagnosed with botulism after ingesting chopped garlic in soybean oil. This was characterized as the second largest outbreak of botulism reported in North America (St. Louis et al., 1988), which prompted Health Canada to seek voluntary industry compliance with the incorporation of a microbial hurdle approach (i.e., acidification and refrigeration) for garlic-in-oil products to control the growth of C. botulinum. Growth and toxin production by C. botulinum has been confirmed in outbreaks in a number of commercially prepared garlic-in-oil products (Krusell and Lohse, 2003; Morse et al., 1990; St Louis et al., 1988). As a result of the outbreaks, the U.S. FDA prohibited the manufacture of garlic-in-oil products which are only protected by refrigeration, therefore acidifying agents must be added to such products to ensure safety (Morse et al., 1990).

Some other plant and mushroom products stored in oil are considered to present a similar level of risk of causing botulism as garlic-in-oil products. Illness data from other countries have implicated a variety of commercially prepared and home-preserved plant and mushroom products stored in oil (e.g., mushrooms (CDR, 1998; Gyle, 1999); eggplant (MMWR, 1995); peppers (Barker et al., 1977) and pesto (Chiorboli et al., 1997)) as a source of botulism. The potential to develop toxin without apparent evidence of spoilage, puts these products into a high-risk category.

5.2  Yeasts and moulds

Yeasts and moulds may grow in some foods in sealed packages even if the pH is less than 4.6, if the food has not been treated by heat or inhibitors/hurdles (for example, additives) to prevent their growth. Yeast and moulds grow under aerobic conditions and are not expected to grow under anaerobic conditions. Production methods should ensure that the growth of yeast and mould is controlled. If yeasts or moulds grow, they can increase the pH sufficiently to permit the growth of foodborne pathogens such as C. botulinum (Huhtanen et al., 1976; Wade and Beuchat, 2003). On the other hand, growth of yeast and moulds will not affect the a_w of the product. Yeasts and moulds can grow at temperatures ranging from 10 to 35°C (very few species can grow below and above this range), at pH values from 2 to above 9 (Tournas et al., 2001), and at a_w values greater than 0.61 (Beuchat, 1983).

6.  Guidance for the safe manufacture of plant and mushroom products stored in oil

The controls outlined in Appendix 1 are given as a guideline to manufacturers of plant and mushroom products stored in oil. Products which comply with these criteria are considered to represent a low risk of causing foodborne illness. Products that do not meet the criteria in Appendix 1 should be evaluated on a case-by-case basis, to ensure the manufacturing of safe products. Additional information may be required from the manufacturer, such as the results of challenge test studies or published scientific studies supporting the safety of their products. Processing and storage parameters should ensure that hazards likely to occur have been addressed and mitigated.

6.1  Control measures

There are a number of options which will allow for the safe production of these plant and mushroom products stored in oil. They include: controlling water activity and/or pH, using inhibitor agents (for example, food additives) and/or applying a thermal treatment. Refrigeration is also an option, however, prolonged refrigeration alone is not recommended because domestic refrigerators, as well as refrigeration at retail and during transport, cannot be guaranteed to maintain a temperature ≤ 4°C (Nguyen et al., 2014). There is also the possibility that recommendations on product storage may not be followed by the consumer.

Plants and mushrooms naturally have a pH > 4.6 and a_w > 0.94, and must either be properly acidified (to a pH equilibrium of < 4.6), dried/brined (to a a_w < 0.94) or thermally processed before being covered with oil so that the finished product (plant or mushroom in oil) is not conducive to C. botulinum growth.

Given the health risks associated with the potential contamination of plant and mushroom products in oil with C. botulinum, it is recommended that all domestic and imported products adhere to at least 1 of the seven processing and storage scenarios outlined in Appendix 1. These scenarios are in accordance with Division B.27 of the Food and Drug Regulations (Low-Acid Foods Packaged In Hermetically Sealed Containers, Government of Canada, 2018b) and/or Sections 4 and 7 of the Food and Drugs Act (Government of Canada, 2018a), as appropriate to the specific product. Furthermore, appropriate labelling (e.g., date markings and storage instructions) should be ensured/applied, as per the Food and Drug Regulations (Government of Canada, 2018b) and the Consumer Packaging and Labelling Act (Government of Canada, 2018c). Should the finished product parameters and storage conditions be inconsistent or fall outside of the stated limits throughout the shelf-life of the products, these products could be potentially hazardous.

The a_w and pH values of products in oil may be difficult to measure accurately depending upon a number of factors such as food type and instrument. Occlusion by the oil portion may prevent the ‘display’ of water vapour pressure and oils can foul and contaminate the pH electrode. Proper sample preparation such as separation of the oil from the rest of the product (plants or mushrooms), as described in MFLP-66 (Health Canada, 2014a) and MFHPB-03 (Health Canada, 2014b), is an important step to ensure accurate measurement of the a_w and pH values.

The processing and storage parameters set out in Appendix 1 may be used for the safe production of plant and mushrooms products stored in oil. The products whose characteristics do not match those listed in Appendix 1 are considered to have the potential to produce an unsafe food if the manufacturer is not able to demonstrate that the hazards associated with the products are controlled. To this end, processors wanting to establish different processing and storage parameters for the manufacture of plant and mushroom products-in-oil should be able to demonstrate safety of their products. The Bureau of Microbial Hazards, Food Directorate, Health Canada, may be consulted to conduct/provide guidance on the safety evaluation on these products. To evaluate safety and process control throughout production lots to be examined, supporting documentation should be provided on the safety controls being used, along with laboratory analysis results of the following:

• product pH;
• water activity (a_w );
• water phase salt; and
• detection/enumeration of pathogens using an acceptable sampling plan and methods in which the “application” section is appropriate for the intended purpose.

Should the information provided is not considered adequate to determine the safety of the products, additional data supporting the safety of the food would be requested (e.g., C. botulinum challenge studies data (Health Canada, 2010)). Processors are encouraged to obtain expert advice prior to the initiation of laboratory studies in order to discuss the nature and data required.

6.2  Assessing plant and mushroom products stored in oil

In order for regulatory authorities to conduct a proper health risk assessment, a complete description of all ingredients should be provided. It should be indicated whether fresh or dried plant and mushroom ingredients are used. The actual storage temperature should be noted, as well as the storage temperature recommended on the label. The "Best Before" date and lot number should also be noted. Where possible, analytical results should be obtained from at least five sample units per lot for the following determinations: pH, water activity and water phase salt.

To assess the level of risk posed by these products, additional information such as microbiological data and time-temperature profile records (e.g., heat-process, storage temperatures) should be submitted as part of a health risk assessment to determine the level of risk. If it is a new product or a new process, the manufacturer should ensure the safety of the product and thoroughly document the details about their process.

7. References

• Austin, J. W. (2001). Clostridium botulinum. In: Food Microbiology: Fundamentals and Frontiers 2nd edition. (E.d. M.P. Doyle et al.), ASM Press, Washington, D.C. pp. 329-349.

• Barker, W.H., Weissman, J.B. and V.R. Dowell. (1977). Type B botulism outbreak caused by a commercial food product. JAMA. 237(5): 456-459.

• Beuchat, L.R. (1983). Influence of water activity on growth, metabolic activities and survival of yeast and molds. J. Food Prot., 46(2): 135-141.

• Bilusic, M., Pattathil, J., Brescia, M., McHugh, W., Zaboski, M. and B. Schanzer. (2008). Recurrent bulbar paralysis caused by botulinum toxin type B.Clin. Infect. Dis., 46(8): e72-e74.

• Biology online. (2005-2008). Available at:  http://www.biology-online.org/dictionary/Main_Page (Accessed July 6, 2016).

• CDR (Communicable Disease Report) Weekly. (1998). Botulism associated with home-preserved mushrooms. Public Health Laboratory Service. Vol 8 No 18, 1 May.

• Chioroboli, E., Fortina, G. and G. Bona. (1997). Flaccid paralysis caused by botulinum toxin type B after pesto ingestion. Pediatr. Infest. Dis. J., 16: 725-726.

• Florida Department of Health. (1999). Foodborne Illness Surveillance and Investigation Annual Report, Florida, 1999. pp. 22-24.

• Government of Canada. (2018a). Food and Drugs Act. Available at: http://laws-lois.justice.gc.ca/eng/acts/f-27/ (Accessed on April 30, 2018).

• Government of Canada. (2018b). Food and Drug Regulations. Available at: http://laws-lois.justice.gc.ca/eng/regulations/c.r.c.,_c._870/ (Accessed on April 30, 2018).

• Government of Canada. (2018c).  Consumer Packaging and Labelling Act.  Available at:  http://laws-lois.justice.gc.ca/eng/acts/C-38/  (Accessed on April 30, 2018).

• Gyle, N. (1999). Type A botulism intoxication associated with home-prepared mushroom. Connecticut, 1998. Conn. Epi., 19:9-10.

• Hatheway, C. L. (1993). Clostridium botulinum and other clostridia that produce botulinum neurotoxin. In: Clostridium botulinum, Ecology and control in foods (Eds. Hauschild A. H. W. and K. L. Dodds) Marcel Dekker, Inc., New York, USA. pp. 3-20.

• Health Canada. (2008). Garlic in oil. Available at: http://publications.gc.ca/collections/collection_2008/hc-sc/H50-3-2E.pdf (Accessed on August 15, 2017).

• Health Canada. (2010). Clostridium botulinum Challenge Testing of Ready-to-Eat Foods. Available at: https://www.canada.ca/en/health-canada/services/food-nutrition/legislation-guidelines/policies/clostridium-botulinum-challenge-testing-ready-foods-2010.html (Accessed on August 15, 2017).

• Health Canada. (2013). Food safety tips for vegetable and herbs stored in oil. Available at: http://healthycanadians.gc.ca/eating-nutrition/healthy-eating-saine-alimentation/safety-salubrite/fruits-vegetables-legumes-fruits/oil-huile-eng.php (Accessed on October 25, 2016).

• Health Canada. (2014a). MFLP-66. Determination of Water Activity using the Decagon Aqualab. In: Compendium of Analytical Methods, Volume 3. Available online at: https://www.canada.ca/en/health-canada/services/food-nutrition/research-programs-analytical-methods/analytical-methods/compendium-methods/laboratory-procedures-microbiological-analysis-foods-compendium-analytical-methods.html (Accessed on August 15, 2017).

• Health Canada. (2014b). MFHPB-03. Determination of the pH of Foods Including Foods in Hermetically Sealed Containers. In: Compendium of Analytical Methods, Volume 2. Available online at: https://www.canada.ca/en/health-canada/services/food-nutrition/research-programs-analytical-methods/analytical-methods/compendium-methods/methods-microbiological-analysis-foods-compendium-analytical-methods.html (Accessed on August 15, 2017).

• Health Canada. (2017). List of Permitted Food Additives. Available at: https://www.canada.ca/en/health-canada/services/food-nutrition/food-safety/food-additives/lists-permitted.html (Accessed on August 15, 2017).

• Huhtanen, C.N., Naghski, J., Custer, C.S. and R.W. Russell. (1976). Growth and toxin production by Clostridium botulinum in moldy tomato. Appl. Envir. Microbiol., 32(5):711-715.

• Jalava, K., Selby, K., Pihlajasaari, A., Kolho, E., Dahlsten, E., Forss, N., Bäcklund, T., Korkeala, H., Honkanen-Buzalski, T., Hulkko, T., Derman, Y., Järvinen, A., Kotilainen, H., Kultanen, L., Ruutu, P., Lyytikaïnen, O. and M. Lindström. (2011). Two cases of food-borne botulism in Finland caused by conserved olives, October 2011. Euro Surveill., 16(49): pii=20034.

• Johnson, E.A. (2007). Clostridium botulinum. In: Food Microbiology: Fundamentals and Frontiers, Third edition (eds. M.P. Doyle and L. R. Beuchat). ASM Press, Washington, D.C., U.S.A. pp. 401-421.

• Krusell, L. and N. Lohse.  (2003). A case of human botulism in Denmark after consumption of garlic in chilli oil dressing produced in Germany. Euro Surveill. 7(7):2163. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=2163. (Accessed July 25, 2012).

• 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. 

• MacDonald, K.L., Spengler, R.F., Hatheway, C.L., Hargrett, N.T. and M.L. Cohen. (1985). Type A botulism from sauteed onions. Clinical and epidemiologic observations. JAMA. 253(9):1275-1278.

• Merriam-Webster Dictionary. (2018). Available at: http://www.merriam-webster.com/ (Accessed on April 30, 2018).

• MMWR (Morbidity Mortality Weekly Report). (1995). International Notes Type B botulism associated with roasted eggplant in oil – Italy, 1993. MMWR Weekly. 44 (02); 33-36.

• Morse, D.L., Pickard, L.K., Guzewich, J.J., Devine, B.D., and M. Shayegani. (1990). Garlic-in-oil associated botulism: episode leads to product modification. Am. J. Public Health, 80(11):1372-1373.

• Nguyen, L., Bussey, J., Catford, A., and J. Austin. (2014). Modelling the effect of temperature and time on time-to-toxin production of Clostridium botulinum in preserved garlic. Health Canada Science Forum 2014.

• Parkinson, N.G. and K.A. Ito. (2007). Clostridium botulinum. In: Foodborne Infections and Intoxications. Third edition (eds. H.P. Riemann and D.O. Cliver). Academic Press Inc., San Diego, CA. pp. 485-521.

• PHAC (Public Health Agency of Canada). (2007). Public Health Agency of Canada Strategic Plan 2007-2012, Information - Knowledge - Action. Available at: http://www.phac-aspc.gc.ca/publicat/2007/sp-ps/index-eng.php (Accessed on July 7, 2012).

• Pingeon, J.M,, Vanbockstael, C., Popoff, M.R., King, L.A., Deschamps, B., Pradel, G., Dupont, H., Spanjaard, A., Houdard, A., Mazuet, C., Belaizi, B., Bourgeois, S., Lemgueres, S., Debbat, K., Courant, P., Quirin, R., and P. Malfait. (2011).Two outbreaks of botulism associated with consumption of green olive paste, France, September 2011. Euro Surveill., Volume 16 Issue 49.

• Roberts, E., Wales, J.M., Brett, M.M., and P. Bradding. (1998). Cranial-nerve palsies and vomiting. Lancet, 352(9141):1674.

• Solomon, H.M. and D.A. Kautter. (1988) Outgrowth and Toxin Production by Clostridium botulinum in bottled chopped garlic. J. Food Prot., 51(11):862-865.

• St Louis, M.E., Peck, S.H.,  Bowering, D.,  Morgan, G.B., Blatherwick, J.,  Banerjee, S., Kettyls, G.D., Black, W.A., Milling, M.E., Hauschild, A.H., et al. (1988) Botulism from chopped garlic: delayed recognition of a major outbreak. Ann. Intern. Med., 108 (3):363-368. 

• Sugiyama, H. (1990). Botulism. In: Foodborne diseases, (ed. D.O. Cliver). Academic Press Inc., San Diego, CA.

• Tournas, V., Stack, M.E., Mislivec, P.B., Koch, H.A., and R. Bandler. (2001). BAM: Yeasts, Molds, and Mycotoxins. Available at: http://www.fda.gov/Food/FoodScienceResearch/LaboratoryMethods/ucm071435.htm. (Accessed on March 19, 2019).

• U.S.  FDA (Food and Drug Administration. (2011). Fish and Fishery Products Hazards and Controls Guidance. Available at: http://www.fda.gov/downloads/food/guidanceregulation/UCM251970.htm. (Accessed on March 19, 2019).

• Viray, M. A., Wamala, J., Fagan, R., Luquez, C., Maslanka, S., Downing, R., Biggerstaff M., Malimbo M., Kirenga J.B., Nakibuuka J., Ddumba E., Mbabazi W. and D.L. Swerdlow. (2014). Outbreak of Type A Foodborne Botulism in a Boarding School – Uganda, 2008. Epidemiology and infection. 142 (11): 2297–2301.

• Wade, W.N. and L.R. Beuchat. (2003). Proteolytic fungi isolated from decayed and damaged raw tomatoes and implications associated with changes in pericarp pH favourable for survival and growth of foodborne pathogens. J. Food Prot., 66(6):911-917.

Appendix 1: Processing and storage parameters for the safe manufacturing of plant and mushroom products stored in oil^{Footnote *}