These Principles are intended to give guidance on the establishment and application of microbiological criteria for foods at any point in the food chain from primary production to final consumption.
The safety of foods is principally assured by control at the source, product design and process control, and the application of Good Hygienic Practices during production, processing (including labelling), handling, distribution, storage, sale, preparation and use, in conjunction with the application of the HACCP system. This preventive approach offers more control than microbiological testing because the effectiveness of microbiological examination to assess the safety of foods is limited. Guidance for the establishment of HACCP based systems is detailed in the Codex Guidelines for the Application of HACCP. Microbiological criteria should be established according to these principles and be based on scientific analysis and advice, and where sufficient data are available, a risk analysis appropriate to the foodstuff and its use. Microbiological criteria should be developed in a transparent fashion and meet the requirements of fair trade. They should be reviewed periodically for relevance with respect to emerging pathogens, changing technologies, and new understandings of science.
A microbiological criterion for food defines the acceptability of a process, a product or a food lot, based on the absence or presence, or number of microorganisms, and/or quantity of their toxins/metabolites, per unit(s) of mass, volume, area or lot.
2.1 A microbiological criterion consists of:
a statement of the microorganisms of concern and/or their toxins/metabolites and the reason for that concern. (see § 5.1);
the analytical methods for their detection and/or quantification (see § 5.2);
a plan defining the number of field samples to be taken and the size of the analytical unit (see § 6);
microbiological limits considered appropriate to the food at the specified point(s) of the food chain (see § 5.3);
the number of analytical units that should conform to these limits.
2.2 A microbiological criterion should also state:
the food to which the criterion applies,
the point(s) in the food chain where the criterion applies,
any actions to be taken when criterion is not met.
2.3 When using microbiological criteria for assessing products it is essential, in order to make the best use of money and manpower, that only appropriate tests be applied (see § 5) to those foods and at those points in the food chain that offer maximum benefit in providing the consumer with a food that is safe and suitable for consumption.
3.1 Microbiological criteria may be used to indicate the microbiological status of raw materials, ingredients and end-products at any stage of the food chain as appropriate. They may be relevant to the examination of foods, including raw materials and ingredients, of unknown or uncertain origin or when other means of verifying the efficacy of HACCP based systems and Good Hygienic Practices are not available.
Generally, microbiological criteria may be applied to define the distinction between acceptable and unacceptable raw materials, ingredients, products, lots, or processes by regulatory authorities and/or food business operators.
Microbiological criteria can be used to check compliance with hygienic and microbiological safety provisions in regulations.
Mandatory microbiological criteria shall be limited to those products and/or points of the food chain where no other more effective tools are available, or where they are expected to improve the degree of protection offered to the consumer. Where these are appropriate they shall be product-type specific and only applied at the point of the food chain as specified in the regulation.
Depending on the assessment of the risk to the consumer, the point in the food chain and the product-type specified, the regulatory control actions may be sorting, reprocessing, rejection or destruction of product, and/or further investigation.
Criteria used for this application may be contained in a Codex Standard, may form part of a technical regulation as defined by the World Trade Organization Agreement on the Application of Sanitary and Phytosanitary Measures, or any other legal requirement.
In addition to checking compliance with regulatory provisions (see § 3.1.1) microbiological criteria may be applied by food business operators to examine end-products as one of the measures to verify and/or validate the efficacy of the HACCP system.
Such criteria will be specific for the product, the production-line or -site. They may be stricter than the criteria used for regulatory purposes and should, as such, not be used for legal action.
They may also be used by the processor to assess products and raw materials of unknown origin or those not known to have been produced according to Good Hygienic Practices and by applying HACCP principles.
3.2 Microbiological criteria as described here, are not normally suitable for monitoring Critical Limits as defined in the Codex Guidelines for the Application of HACCP. Monitoring procedures must be able to detect loss of control at a Critical Control Point (CCP). Monitoring should provide this information in time for corrective actions to be taken to regain control before there is a need to reject the product. Consequently, on-line measurements of physical and chemical parameters are often preferred to microbiological testing because results are often available more rapidly and at the production site.
Moreover, the establishment of Critical Limits may need other considerations than those described in this document.
4.1 The hygiene, including safety, of foods should be ensured through the application of Good Hygienic Practices, and the development and implementation of a HACCP plan or an equivalent HACCP-based system.
A microbiological criterion should be established and applied only where there is a definite need and where its application is practical. Such need is demonstrated, for example, by epidemiological evidence that the food under consideration may represent a public health hazard and that a criterion is meaningful for consumer protection, or by the result of a risk analysis. The criterion should be technically attainable by applying good manufacturing practices (codes of practice).
4.2 To fulfil the purposes of a microbiological criterion, consideration should be given to:
the evidence of actual or potential hazards to health;
the microbiological status of the raw material(s);
the effect of processing on the microbiological status of the food;
the likelihood and consequences of microbial contamination and/or growth during subsequent handling, storage and use;
the category(s) of consumers concerned;
the cost/benefit ratio associated with the application of the criterion;
the intended use of the food.
4.3 The number and size of analytical units per lot tested should be as stated in the sampling plan and should not be modified. A lot should be not be subjected to repeated testing, in order to bring the lot into compliance.
5.1.1 For the purpose of this document these include:
bacteria, viruses, yeasts, moulds, and algae;
parasitic protozoa and helminths;
their toxins/metabolites.
5.1.2 The microorganisms included in a criterion should be widely accepted as relevant - as pathogens, as indicator organisms or as spoilage organisms - to the particular food and technology. Organisms whose significance in the specified food is doubtful should not be included in a criterion.
5.1.3 The mere finding, with a presence-absence test, of certain organisms known to cause foodborne illness (e.g. Clostridium perfringens and Vibrio parahaemolyticus) does not necessarily indicate a hazard.
5.1.4 Where pathogens can be detected directly and reliably, consideration should be given to testing for them in preference to testing for indicator organisms. If a test for an indicator organism is applied, there should be a clear statement whether the test is used to indicate unsatisfactory hygienic practices or a health hazard.
5.2.1 Whenever possible, only methods for which the reliability (accuracy, reproducibility, inter-and intra-laboratory variation) has been statistically established in comparative or collaborative studies in several laboratories should be used. Moreover, preference should be given to methods which were validated for the commodity concerned preferably in relation to reference methods elaborated by international organizations.
While methods should be the most sensitive and reproducible for the purpose, methods to be used for in-plant testing might often sacrifice to some degree sensitivity and reproducibility in the interest of speed and simplicity. They should, however, have been proved to give a sufficiently reliable estimate of the information needed.
Methods used to determine the suitability for consumption of highly perishable foods, or foods with a short shelf-life, should be chosen wherever possible so that the results of microbiological examinations are available before the foods are consumed or exceed their shelf-life.
5.2.2 The microbiological methods specified should be reasonable with regard to complexity, availability of media, equipment etc., ease of interpretation, time required and costs.
5.3.1 Limits used in criteria should be based on microbiological data appropriate to the food and should be applicable to a variety of similar products. They should therefore be based on data gathered at various production establishments operating under Good Hygienic Practices and applying the HACCP system.
In the establishment of microbiological limits, any changes in the microflora likely during storage and distribution (e.g. decrease or increase in numbers) should be taken into account.
5.3.2 Microbiological limits should take into consideration the risk associated with the microorganisms, and the conditions under which the food is expected to be handled and consumed. Microbiological limits should also take account of the likelihood of uneven distribution of microorganisms in the food and the inherent variability of the analytical procedure.
5.3.3 If a criterion requires the absence of a particular microorganism, the size and number of the analytical unit (as well as the number of analytical sample units) should be indicated.
5.3.3 It should be borne in mind that no feasible sampling plan can ensure complete absence of a particular organism in a lot, and thus that criteria cannot assure the safety of a lot.
6.1 A sampling plan includes the sampling procedure and the decision criteria to be applied to a lot, based on examination of a prescribed number of sample units and subsequent analytical units of a stated size by defined methods. Sampling plans should be administratively and economically feasible.
In particular, sampling plans should take into account:
the severity of the hazard and an assessment of the likelihood of its occurrence (risk),
the susceptibility of the target group of consumers
The heterogeneity of distribution of microorganisms
the acceptable quality level ( AQL, percentage of defective sample units) and the desired statistical probability of accepting a defective lot.
For many applications 2-or 3-class attribute plans may prove useful. (See Annex I or ICMSF, Microorganisms in Foods, 2. Sampling for Microbiological Analysis. Principles and Specific Applications, 2nd Edition, 1986).
6.2 The statistical performance characteristics or operating characteristics curve should be provided in the sampling plan. The sampling method should be defined in the sampling plan. The time between taking the field samples and analysis should be as short as reasonably possible, and during transport to the laboratory the conditions (e.g. temperature) should not allow increase or decrease of the numbers of the target organism, so that the results reflect - within the limitations given by the sampling plan - the microbiological conditions of the lot.
7.1 The test report shall give the information needed for complete identification of the sample, the sampling plan, the test method, the results and, if appropriate, their interpretation.
