Microbiological limits

Just give me the limit already!

An International perspective:

When it comes to conducting a hazard analysis, microbiological risks and their associated limits are often difficult to define. Although everybody in industry recognises the need for microbial limits, newcomers often do not have the technical knowledge in the field to accurately write up specifications for their products. This inevitably results in a search for regulations, as one would for contaminants such as pesticides and heavy metals. However, consistent and specific micro limits are often hard to find. Unfortunately microbiological guidelines are predominantly set up for a limited list of products, in general for single agricultural products. Therefore it is difficult to find a specification for more complex foods such as baked pasta dishes or cooked stews.

One of the major reasons why microbiological specifications are generally conservative, is because microbiological testing is seen as a tool that contributes to food safety, but is fundamentally supported by other facets such as product and process design (European Commission, 2016). Microbiological testing needs to take into account various factors, one of which is the ability of the product to support the growth of the bacteria being tested for.

Internationally, Codex Alimentarius is advised by the Joint FAO/WHO Expert Meetings on Microbiological Risk Assessment (JEMRA). JEMRA uses a risk based model to advise Codex on new and emerging microbiological risks, which in turn advises signatories to Codex.

The European Union issued regulations on the microbiological criteria for foodstuffs in 2005. The regulations cover mainly pathogens and not indicator organisms and stipulate methodology for testing. The European regulation gives details regarding the number of samples to be tested and how many of these samples can exceed the limit, if any. For example, for sprouts, within 5 samples, no sample may contain Salmonella in 25 g when tested according to EN/ISO 6579 (Official Journal of the European Union, 2005).

The Food and Drug administration (FDA) of the United States of America has a variety of regulations and guidance documents published that cover aspects of microbiological testing, but not a single standard. These cover items such as seafood [1], fruit juice [2] and low acid canned foods [3]. It is therefore recommended that manufacturers exporting, or looking for reference documentation, do a product specific search on the FDA website. The FDA also publishes the “Bad Bug Book” that covers various pathogens and their growth conditions [4]. It is a useful guide for professionals in the food industry having to write specifications.

The Australia New Zealand food standards authority has a microbiological standard (1.6.1), published as part of their food standards. The document includes similar information as with the European regulation, but covers fewer products. It is also interesting to note that the standard not only covers pathogens, but also indicators of poor hygiene such as coliforms (FSANZ, 2000).

It is important that microbiological specifications be applied to the entire shelf life of the product and not just at the time of production. Product developers need to take into account the physical and chemical parameters of the product during storage that could support growth. In addition, abuse of the product by the consumer, such as incorrect storage temperature should also be considered when setting up micro limits. Thus, although the legal requirements must be consulted, the risk of the product and its storage must also be carefully considered. It always remains the responsibility of the producer to supply safe food even in the absence of legislation.

Article by: Norah Hayes

References:
1. FDA. 2010. Compliance Program Guidance Manual: Import Seafood Products Compliance Program – 7303.844. Available from: <http://www.fda.gov/downloads/Food/ ComplianceEnforcement/UCM219993.pdf>. [25 April 2016].
2. FDA. 2015. Compliance Program Guidance Manual: Juice HACCP Inspection Program – 7303.847. Available from: <http://www.fda.gov/Food/ComplianceEnforcement/ FoodCompliancePrograms/ucm236946.htm>. [25 April 2016].
3. FDA. 2010. Compliance Program Guidance Manual: Domestic Acidified and Low-Acid Canned Foods – 7303.803A. Available from: <http://www.fda.gov/ downloads/Food/ComplianceEnforcement/ UCM406274.pdf>. [25 April 2016].
4. FDA. 2012. Bad Bug Book, Foodborne Pathogenic Microorganisms and Natural Toxins. Second Edition. Available from: <http://www.fda.gov/downloads/Food/ FoodborneIllnessContaminants/UCM297627.pdf>. [25 April 2016].

Microbiological limits

Mycotoxic Foods

Screen Shot 2016-05-11 at 9.35.03 AM
Aflatoxin B1 chemical structure

Mycotoxins are potentially serious contaminant in foods. These toxins are produced by fungi when storage conditions favour fungal growth, such as in damp grain. Mycotoxins are not easily destroyed by thermal processes that would kill fungi, such as cooking or freezing. As such, prevention of fungal contamination of foods is critical as these toxins can cause illnesses or even death. The most significant mycotoxins include aflatoxins, citrinin, ergot alkaloids, fusarium, ochratoxin, and patin [1]. South African limits for mycotoxin levels in certain foods have been set for Ergot sclerotia, patulin and aflatoxin [2].

Ergot alkaloids are produced by Claviceps species and affect grass species, including cereals. The toxin causes Ergotism which affects the blood supply to the limbs and central nervous system. It is suspected that the Salem witchcraft allegations arose from rye infected with Claviceps resulting in convulsive ergotism. In South Africa grains must contain less than 0.05% Ergot sclerotia by mass.

Patulin is an antiobiotic produced by the soft rot blue mould, Penicillium expansum found on fruit infected. It is toxic to humans and the South African limit for patulin is 50 μg/l in apple juice and other beverages containing apple derivatives.

The risks of mycotoxin contamination are controllable if products are sampled and tested correctly, and health authorities and manufacturers respond appropriately.

Manufacturers must be aware of the legal limits for mycotoxins that must be abided by. As always, manufacturers have the responsibility to ensure their food products are safe.

As a manufacturer, it would be your responsibility to set up specifications covering potential contaminants not only for your finished product, but also raw materials. It is vital to cover all regulations when compiling your specifications, but also to look at, based on industry experience, the chemical, physical and microbial contaminants associated with your product.

Aflatoxin conundrum

Aflatoxins, of which aflatoxin B1 is the most toxic, are more strictly regulated than other mycotoxins. This is due to the risks of chronic, low-level exposure which may result in numerous conditions including immune suppression and even cancer. Studies suggest that increased exposure to aflatoxin increases risk of cancer, especially liver cancer [1]. No ready-to-eat food in South Africa may contain more than 10 μg/kg of aflatoxin (with aflatoxin B1 < 5 μg/kg).

Unfortunately, the fungi that produces aflatoxins grows on maize and peanuts, which are both staple foods. Peanuts are high in protein and due to its high nutritional value is frequently used in nutritional programmes in poorer communities. In 2001 greater than 30 times the legal limit of aflatoxin B1 was found in non-commercial peanut butter used in an Eastern Cape Primary School Nutrition Programme [3]. This potentially increasing cancer risk for millions of school children from 1994.

High levels of aflatoxin can be due to manufacturers’ ignorance, or in some cases the unethical practice of combining contaminated, with uncontaminated product to reduce the level of aflatoxin in the final
product.

Articles by: Gillian de Villiers, co-authored by Norah Hayes

References:
1. Clin. Microbiol. Rev. July 2003 vol. 16 no. 3 497-516 Mycotoxins, J.W. Bennett, and M. Klich
2. Regulations governing tolerance for fungus produced toxins in foodstuffs R.1145 of 2004, October 8.
3. MRC policy brief. August 2001 Aflatoxin in peanut butter (http://scienceinafrica.com/health/aflatoxin-peanut-butter-mrc-policy-brief)

Suppliers

My supplier did what?

Many manufacturers are unaware of the extent to which the safety of their end product is dependent on their suppliers. Like the man in the image to the left, each producer in the food chain plays a vital role in holding the chain together to maintain food safety and legality of the end product.

As a food manufacturer you may have asked yourself questions to the tune of “I produce chocolate brownies, why should I worry about pesticides or heavy metals!” – The problem is that our suppliers often aren’t aware of the legal limits of contaminants related to their products. This is often exacerbated when buying raw materials from distributors or importing products, as these legal limits sometimes differ from country to country.

It is important to realise that these limits set by the South African government are not guidelines and that it is a criminal offence to sell product that does not meet the legal limits. Ultimately the onus is on the manufacturer to ensure that their supplier provides them with product that is safe and legally compliant.
So what’s the solution? Firstly, know the legal limits of the products being supplied to you, and secondly if your supplier is supplying product that is legal. To assist producers a set of tools are available to monitor and manage suppliers and include product specifications, certificates of analysis (CoA), supplier assessments, questionnaires, audits and lab tests. To be effective these tools require you as the producer to know what questions to ask your suppliers. Let’s take a brief look.

First, what are the legal limits? We will cover some of the regulations in this issue of Chimera News, but if you have specific questions about the regulations for your product, give us a call.

Ask your suppliers for a specification for each product they supply you with. At minimum these will contain the ingredients, allergens and legal limits for contaminants applicable to the product.

Request a CoA for each batch of product. This is a record showing that the product conforms. If legal limits exist these must appear on the CoA or a laboratory report issued with the CoA.

Supplier assessments, questionnaires and audits assess the supplier’s level of compliance to food safety standards. Ask your supplier what food safety certifications they have, if any, and if they comply to good manufacturing practices (GMP).

Lastly, lab tests can be used to verify conformity, but are expensive and most effective when combined with a risk assessment to determine products that are at greatest risk. Where possible place the responsibility for raw material testing on the supplier.

These are just some of the tools available to help producers manage their end of the supply chain more effectively.

Article by: David James Scott