What Is Total Aerobic Count?
Total aerobic mesophilic bacteria count is the determination of the total number of live bacteria that can grow in the sample at a certain temperature. The sample is diluted, inoculated into the medium, incubated and the colonies formed are counted. The result is given as colony forming units per gram or milliliter (cfu/g or cfu/mL).
Purpose of Total Aerobic Count
The aim is to evaluate the overall microbiological quality of the product and the state of production hygiene. A high count alone does not indicate the presence of a pathogen; It indicates a disruption in the hygiene chain.
Which Products Is Total Aerobic Count Applied To?
- Milk and dairy products
- Meat and meat products
- Ready meals and cold chain products
- Unlu mamuller
- Fruit vegetables and fresh products
In Which Sectors Is Total Aerobic Count Used?
Standards Related to Total Aerobic Count
- TS EN ISO 4833-1 (cast plate method, 30 °C)
- TS EN ISO 4833-2 (spread plate method, 30 °C)
- TS EN ISO 6887 series (sample preparation and dilution)
- TS EN ISO 7218 (general rules for microbiological examination)
Total Aerobic Count Conditions
- Incubation
- At standard defined temperature and time
- Dilution
- Decimal dilution series according to ISO 6887
- count range
- Plaques within the countable colony range defined in the standard are evaluated.
Equipment for Total Aerobic Count
- Sterile cabin and microbiology laboratory
- Incubators
- Autoclave and media preparation system
- Stomacher (sample homogenizer)
- Colony counter
Sample Requirements for Total Aerobic Count
- 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.
- Sample quantity is determined according to the analysis plan
- Date, time and temperature of collection should be recorded
- The number of samples taken from the same batch must be in accordance with the sampling plan
Duration of Total Aerobic Count
The result cannot be given before the incubation period defined in the standard is completed. This period is determined by the method itself and cannot be shortened.
Total Aerobic Count Procedure
- 1The sample is weighed and homogenized under aseptic conditions.
- 2A decimal dilution series is prepared.
- 3Planting is done on the medium from the dilutions.
- 4Plates are incubated at the defined temperature and duration.
- 5Colonies on plates within countable range are counted.
- 6The result is calculated as cfu/g or cfu/mL with the dilution factor.
Total Aerobic Count 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 total count is an indicator of quality, not safety: in fermented products, a high count is normal and expected from the product. The result cannot be interpreted without considering the product category.
Total Aerobic Count Report
- Sample description, batch and receiving information
- Standard and method applied
- Incubation conditions
- Result (cfu/g or cfu/mL) 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 authorisationsRelated Regulations
- Regulation (EC) 2073/2005 on Microbiological Criteria for Foodstuffs
- Food Hygiene Regulation (EC) 852/2004
Food Testing — What Does This Testing Field Cover?
The section below describes the field that the Total Aerobic Count 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 Total Aerobic Count
Does a high total count mean the product is defective?
Not necessarily. High counts are expected in fermented products and raw foods. The count is evaluated based on the product category and the criteria defined for that category.
Does a total count replace pathogen screening?
It doesn't pass. Pathogens such as Salmonella and Listeria may be present in low numbers and do not appear in the total count. If a pathogen is sought, a method specific to that pathogen should be applied.