Coliform Counting — ISO 4832 / ISO 21528

What Is Coliform?

Coliform count is the determination of the number of a group of bacteria used as a hygiene indicator. Enterobacteriaceae encompasses a larger family and is preferred over coliform in modern hygiene assessment. Both are grown and counted on selective media.

Purpose of Coliform

The aim is to evaluate production hygiene and recontamination after heat treatment. The presence of Enterobacteriaceae in a heat-treated product indicates inadequacy of the process or post-process contamination.

Which Products Is Coliform Applied To?

Pasteurized milk and dairy products
Heat-treated meat products
Ready meals and cold chain products
Drinking and domestic water
Ice cream and desserts

In Which Sectors Is Coliform Used?

FoodAgricultureRetailEnvironment

Standards Related to Coliform

TS ISO 4832 (coliform counting — colony counting technique)
TS EN ISO 21528-1/-2 (Enterobacteriaceae detection and counting)
TS EN ISO 9308-1/-2 (E. coli and coliform in water)
TS EN ISO 7218 (genel kurallar)

Coliform Conditions

Culture medium: Selective media defined in the standard
Incubation: At standard defined temperature and time
Verification: Biochemical confirmation on suspicious colonies

Equipment for Coliform

Sterile cabinet and incubators
Autoclave and media preparation system
Membrane filtration device (for water samples)
Colony counter

Sample Requirements for Coliform

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.
Water samples must be delivered to the laboratory in a sterile container and within a defined time.
Neutralization is required for chlorinated water samples
Sample quantity is determined according to the sampling plan

Duration of Coliform

Incubation time is defined in the standard; Additional time is added in cases where verification is required.

Coliform Procedure

1The sample is prepared and diluted aseptically.
2Planting is done on selective medium; Membrane filtration is applied to water samples.
3It is incubated at defined temperature and time.
4They are considered typical colonies.
5If necessary, biochemical confirmation is performed.
6The result is calculated as cfu/g, cfu/mL or cfu/100 mL.

Coliform Acceptance Criteria

Acceptance criteria are microbiological criteria defined on a food category basis in (EU) 2073/2005. The regulation distinguishes two types of criteria: the food safety criterion (can the product be placed on the market) and the process hygiene criterion (is the production process under control). Which one applies depends on the product category and is confirmed by the text of the applicable regulation.

Evaluation of Results

The Enterobacteriaceae result is more informative than coliform because it covers a broader group and more reliably captures contamination after heat treatment. The presence of these bacteria in raw products is an expected situation.

Coliform Report

Specimen identification and batch information
Applied standard and medium
Incubation conditions
Result and measurement uncertainty
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
(EU) 2020/2184 Drinking Water Directive

Food Testing — What Does This Testing Field Cover?

The section below describes the field that the Coliform 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 Coliform

Koliform mu Enterobacteriaceae mi istemeliyim?

It determines the legislation and specifications. (EC) 2073/2005 mostly uses Enterobacteriaceae in its process hygiene criteria; coliform continues to be requested in some specifications as a traditional indicator.