Listeria Analizi — ISO 11290-1 / ISO 11290-2

What Is Listeria?

Listeria monocytogenes analysis is carried out in two ways: DETECTION (ISO 11290-1) investigates whether the bacteria is present in a defined sample amount; COUNT (ISO 11290-2) determines the amount, if any. Which approach to use depends on whether the product supports Listeria growth and the regulatory criteria.

Purpose of Listeria

The aim is to control the risk of Listeriosis, which can grow even in cold weather and is particularly severe in pregnant women, the elderly and immunocompromised people. The cold chain is not protective for this bacteria; this distinguishes it from other pathogens.

Which Products Is Listeria Applied To?

Ready-to-eat meat and fish products
Soft and ripened cheeses
Sliced delicatessen products
Prepared salads and sandwiches
frozen vegetables

In Which Sectors Is Listeria Used?

FoodAgricultureRetail

Standards Related to Listeria

TS EN ISO 11290-1 (Detection of Listeria monocytogenes and Listeria spp.)
TS EN ISO 11290-2 (counting method)
TS EN ISO 16140 series (alternative method verification)
TS EN ISO 20976-1 (challenge test — reproductive potential)

Listeria Conditions

sample quantity: In determination, the amount defined in the standard and legislation; usually 25g
Enrichment: In semi-selective and selective media, under standard-defined conditions
Census: Direct sowing on selective medium
End of shelf life: Criterion evaluation must be valid throughout shelf life

Equipment for Listeria

Sterile cabinet and incubators
Real-time PCR system
Stomacher and autoclave
Selective media and validation kits
Challenge test infrastructure

Sample Requirements for Listeria

The sample must be sent unopened and in its original packaging, maintaining the cold chain. Whether the sampling method is representative of the batch determines the validity of the result; The result from a single unit is not enough to make a decision about the party.
For end-of-shelf-life evaluation, the product is stored throughout its shelf life.
Sampling plan must comply with legislation
Production environment swab samples can also be evaluated

Duration of Listeria

The detection method takes several days due to the enrichment steps. If an end-of-shelf-life evaluation or challenge test is performed, the period is extended as long as the shelf life of the product.

Listeria Procedure

1The specimen is prepared aseptically.
2Semi-selective enrichment is performed for detection.
3Selective enrichment and cultivation on selective media are applied.
4Typical colonies are verified and species identification is made.
5For counting, the sample is plated directly on selective medium.
6The result is reported as present/absent or cfu/g.

Listeria Acceptance Criteria

(EC) 2073/2005 defines Listeria monocytogenes as a food safety criterion for ready-to-eat foods and stipulates different criteria depending on whether the product supports the growth of Listeria. A stricter approach applies to products that support fertility. The applicable criteria are confirmed from the text of the statute.

Evaluation of Results

The criterion must be met throughout the shelf life; The result obtained on the production day alone is not sufficient. Whether the product supports Listeria growth is shown by ISO 20976-1 challenge testing or mathematical modeling, and this evaluation should be included in the file.

Listeria Report

Sample description, batch and production date
Amount of sample analyzed
Standard and method applied
Result (present/absent or cfu/g)
End of shelf life assessment, if any, results
benchmark

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

(EC) 2073/2005 Microbiological Criteria Regulation

Food Testing — What Does This Testing Field Cover?

The section below describes the field that the Listeria test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Food testing shows that a product is safe for consumption and contains what its label states. The family works along three axes: microbiological safety, chemical safety and nutritional composition. All three require different laboratory infrastructure, a different body of methods and a different turnaround time.

The most distinctive feature of the field is TIME PRESSURE. A steel specimen can wait on a shelf; a raw milk or fresh meat sample cannot. The time the sample was taken, the transport temperature and how long it takes to reach the laboratory directly determine the validity of the result. In food microbiology the cold chain record is therefore an inseparable part of the test report.

On the microbiological side there are two different questions and they must not be confused. DETECTION of a pathogen is a qualitative question: is Salmonella present in the sample or not? ENUMERATION of indicator organisms is a quantitative question and an indicator of production hygiene. The absence of a pathogen in a product does not show that hygiene is good; if the total mesophilic aerobic count is high, there is a problem in the process.

On the chemical side, pesticide residues, mycotoxins, heavy metals, additives, veterinary drug residues and process contaminants (acrylamide, furan, PAH) are measured. Multi-residue methods in this area (QuEChERS-based LC-MS/MS and GC-MS/MS) can screen hundreds of active substances in a single analysis; limits are defined separately for each product–substance pair.

On the composition side, protein, fat, moisture, ash, fibre, sugar profile, fatty acid composition, vitamin and mineral content are determined. These values are the basis of the nutrition declaration on the label and the tolerance ranges are defined in legislation — the difference between the declared value and the measured value must stay within that tolerance.

There is NO CE marking on food, and this shapes how the field works. Conformity is demonstrated through operating a HACCP-based food safety system, complying with labelling rules and not exceeding contaminant, residue and microbiological limits. A test result produces evidence not for a certificate but for a functioning system.

Allergen management carries particular weight. The presence of an undeclared allergen in a product is one of the most frequent causes of food recalls. Analysis here runs together with cleaning validation: it is shown that the line has been cleaned adequately after a production run containing an allergen and that the risk of cross-contamination is under control.

Voluntary schemes have become effectively mandatory in this field. Retail chains require their suppliers to hold a certificate under a GFSI-recognised scheme (BRCGS, IFS, FSSC 22000); without it, getting onto the shelf is practically impossible.

Method groups in this field

Pathogen detection
Detection of Salmonella, Listeria monocytogenes, Campylobacter, Cronobacter and Shiga toxin-producing E. coli; culture-based and molecular methods.
Indicator counts
Total mesophilic aerobic count, Enterobacteriaceae, coliforms and E. coli, coagulase-positive staphylococci, yeasts and moulds, lactic acid bacteria, sulphite-reducing Clostridia.
Pesticide and veterinary residues
Multi-residue screening by LC-MS/MS and GC-MS/MS with QuEChERS extraction.
Mycotoxins and contaminants
Aflatoxins, ochratoxin A, deoxynivalenol, patulin; heavy metals (ICP-MS), acrylamide and PAH compounds.
Nutritional composition
Kjeldahl protein, fat and fatty acid profile, moisture, ash, dietary fibre, sugar profile, vitamin and mineral analyses.
Allergens and authenticity
Gluten, milk, egg, nut and soy allergen analyses; molecular methods for species identification and adulteration detection.

Commonly confused in this field

Sampling is half the result. A sample transported at the wrong temperature or delayed gives an invalid result even if it is analysed correctly in the laboratory.
The absence of a pathogen does not show that hygiene is good; indicator counts give separate information and the two are read together.
A result from a sample taken from a lot can be generalised to the whole lot only if the sampling plan was set up statistically.
Limits are defined in separate regulations by product group and are updated regularly; a conformity decision based on an outdated limit table may be wrong.
For exports, the limits of the destination country may differ from EU limits; the same product may be compliant in one market and non-compliant in another.

Which decisions these results support

Verification of the HACCP plan and process monitoring
The basis for the nutrition declaration and allergen information on the label
Health certificates before export and compliance with destination market limits
Supplier and lot-based acceptance control
Shelf-life studies and determining storage conditions
Producing evidence for audits under GFSI-recognised schemes

Related Tests

Frequently Asked Questions About Listeria

Our product is stored in the cold, isn't the risk of Listeria low?

Backwards. Listeria monocytogenes is one of the few pathogens that can grow at refrigerator temperatures. The cold chain is not protective for this bacteria; long shelf life increases risk.

Challenge test ne zaman gerekir?

When it is necessary to demonstrate whether the product supports the growth of Listeria. This determination must be justified in the file as it changes the criteria to be applied; ISO 20976-1 defines the method for this.