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].