Before collecting samples from the handling environment, answers should be found to the following questions, if possible:
- What is the purpose of sample collection?
- Which microorganisms are of interest?
- Who collects the samples and do they have specific competences?
- Are the sampling tools fit for purpose?
- How to collect samples?
- Which room, area, zone to collect samples from?
- When to collect samples (during, before, or after production)?
- How often to collect samples?
- How many samples must be collected per day?
- What are the conditions of packing, labelling, and transporting samples?
LABRIS uses two types of methods for analysing samples of the handling environment: qualitative and quantitative.
Qualitative analysis methods are used for detection the microorganisms which cause illness in humans (e.g. Salmonella spp. Listeria spp., pathogenic Escherichia coli) or opportunistic microorganisms (e.g. staphylococci, E. coli) and the results are presented in the form of determining the absence (not found) or presence (found) thereof. In order to detect those microorganisms, the sampling area should be as large as possible, advisably within the range from 1,000 cm2 to 3,000 cm2, and the most preferred sample collection method is the abrasive sponge method.
Quantitative analysis methods are mostly used for the quantification of hygiene indicators (e.g. Enterobacteriaceae, aerobic microorganisms, yeasts and moulds) and the results are presented in colony-forming units (CFU) per surface area defined or item examined. This approach is most common in the assessment of the efficiency of cleaning processes and disinfection.
LABRIS offers the following sampling kits for sampling:
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A kit for collecting samples from large surfaces (> 100 cm2) by using the so-called abrasive sponge method. The kit consists of a sponge moistened with buffered peptone water and a pair of disposable plastic gloves packed in a resealable bag. |
Salmonella spp. |
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The kit for collecting samples from smaller areas (< 100 cm2) by using the swabbing method includes sampling tubes with 5 ml of peptone salt solution and a swab. This is used where it is not possible to collect samples with a sponge. |
Pathogenic microorganisms and opportunistic microorganisms (Escherichia coli, staphylococci) |
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Sampling tubes containing 10 ml of peptone salt solution and a swab are used for quantification of hygiene indicators by using the swab method. In the case of using the double swab sampling technique, we also recommend to request a dry, sterile swab with a wooden stem. |
Aerobic microorganisms |
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All regional departments issuing sampling kits. If possible, sampling tools should be kept cool and protected from direct sunlight before collecting samples. After sampling, the samples should be taken to the laboratory as soon as possible. During transportation, samples should be kept and transported in conditions which ensure the viability of microorganisms, but may not cause changes in their count – at a temperature between 1 °C and 8 °C. The best manner for this is to use a thermal box with cooling elements.
Additional information: customer service [email protected]
Collecting samples
Samples are collected from the production or processing environment on the basis of the requirements of EVS EN ISO 18593 ‘Microbiology of the food chain – Horizontal methods for surface sampling’.
A common practice for the quantification of microorganisms is the so-called wet and dry swab technique.
- Gloves should be worn during sampling to prevent the contamination of the sample with the microbiota of the skin of the person collecting the samples. Then, the hands of the person collecting samples with gloves must be properly disinfected with a cloth moistened with alcohol.
- A template sterilised in an autoclave or with gamma radiation is used to collect samples from an area of a specific size. If the re-usable template is used, it should be cleaned with a cloth moistened with alcohol and disinfected before each sampling. At that, it must be made sure that the template is dry before sampling (no visual residues of alcohol on the surface).
- One wet and one dry swab are used for sampling. The wet swab is used to cover the sampling surface, allowing microbe cells to move from the surface to the so-called liquid phase. Then, the liquid with microbes is collected with the dry swab.
- The sterile swab is pressed firmly against the surface sampled and the sample is collected from the surface by turning the stem of the swab around its axis between the fingers and thumb.
- The wet swab is rubbed with circular movements over the entire area within the template in three directions: horizontally, then vertically, and finally diagonally.
- The same technique is repeated with the dry swab. The dry swab should collect all the moisture left on the surface by the wet swab.
- Then, the wet and dry swab are both placed in a tube with peptone salt solution, with the stem of the dry swab broken at the required height.
- The sampling tube is sealed properly and labelled with the data, description of the sampling area, size of the sampling area, and other information, if necessary. The surface area of the sampling area must be specified if the results must be provided in colony-forming units per unit area (CFU/cm²).
- Even though the diluent used does not contain any nutrients important for the growth of microbes, it is advisable to clean and disinfect the surfaces again after sampling.
Those food business operators who prepare ready-to-eat food which may be hazardous to health due to Listeria monocytogenes must collect samples for Listeria monocytogenes analyses from the processing areas and equipment within the framework of the sampling plan.
Samples are collected from the processing environment on the basis of the requirements of EVS EN ISO 18593 ‘Microbiology of the food chain – Horizontal methods for surface sampling’.
Sampling is also regulated by the guidelines developed by the European Union Reference Laboratory.
Further information about the requirements applicable to L. monocytogenes can also be found from the website of the Agriculture and Food Board.
The departments of LABRIS issue Petri dishes with the microbiological culture medium for the collection of air samples by using the sedimentation technique:
- PCA medium for enumeration the total microorganism count;
- DRBC medium for the enumeration of yeasts and moulds.
The Petri dishes required for air samples are issued on pre-order. The orders must be sent to the following email address: [email protected].
Last updated: 03.10.2024
