Sampling For Allergen Analysis
PART 1: The sampling procedure
Sampling of food and food products for allergen testing must be done according to a suitable standard operating procedure (SOP). This ensures that a representative sample is obtained, and that reliable results representing the whole product are produced. If the correct sampling techniques are not employed, results generated by the laboratory may be meaningless.
How does the food quality team decide on a suitable SOP for sampling?
Unfortunately, one sampling plan does not fit all companies. The reason for the analysis will define a company’s sampling plan. Sampling procedures should be decided on once the quality assurance team has completed a risk assessment, in which the starting question would be: ‘What is the purpose of this analysis?’
The flow diagram ‘Sampling for Allergen Testing’, in Figure 1 below, gives an example of the reasons for allergen analysis, and of what questions the QA team should include in their thinking process when drawing samples.
Figure 1: Sampling for allergen testing
When intending to validate or verify allergen control – say, in the case of detecting if equipment has been suitably cleaned – quality-control personnel may consider sending rinse water as a sample matrix, rather than final product. Here, the FACTS swabbing kit may be a helpful sampling tool, to detect if the cleaning action has reached the hard-to-clean places in equipment.
When detecting allergen contamination as one element of an allergen-risk assessment, it is not only important to consider the concentration of the cross-contact allergen in the final product; even more important would be to consider the form. Is it particulate, or readily dispersible?
Imagine that the red dots in the diagram below represent peanut contamination, and the circles show equally-sized samples removed from the batch for peanut detection. It is clear from the diagram that only Portion 2 will test positive for peanut, while Portion 1 will deny its presence. In this case it is important to submit a composite sample, made up of different samples taken from the same batch. This should ensure, as far as possible, that a representative sample has been obtained.
FACTS have created air-dust kits that assist in assessing the risk of contamination from airborne allergens. Ask FACTS for more information regarding the swab and air-dust kits available.
It is important to note that the VITAL® tool requires precautionary labelling automatically if particulate contamination is a possibility. For more information about precautionary labelling and the VITAL® tool, please contact FACTS.
Figure 2: Particulate dispersion of allergen contaminant
According to regulation R. 146, if an allergen-free claim is to be made on packaging, allergen analysis must be done on the final product in order to support the allergen-free claim. In this case, it would be advisable to select a composite sample of three products. Please remember that in order to make an allergen-free claim, it is not sufficient only to complete the analysis; due diligence must also be shown if there is a risk of allergen cross contamination. This means a risk assessment must be completed, in which it would be important to validate or verify that cleaning has been done, and to investigate possible allergen contamination.
PART 2: The testing laboratory partner
Ensuring that sampling is completed correctly is half the battle won; next is to ensure that the analysis is completed using best practice. Quality control in a laboratory is regarded very highly, as this is an indication of accuracy and reproducibility of results. Quality control may include (but is not limited to) duplicate testing and making use of controls.
As far as possible, samples should always be tested in duplicate, which enables the use of statistical analyses of replicate readings to test reproducibility. This increases confidence in the results, and provides evidence for either accepting or rejecting data. When replicate results are not in agreement, one of the two data points must be invalid, and a sample retest is required.
Working closely with the food industry over the past decade, to help customers understand how to control allergens and to identify the origins of seemingly unexplainable allergen contamination, we have learned that continuously finding variances in results more often than not reveals the presence of unequally spread or particulate contamination. Thus, testing samples in duplicate – besides being regarded as good laboratory practice, and playing an important role in a laboratory’s quality control – can also provide key insights into the form that contamination takes.
Duplicate testing, a comprehensive sampling strategy, and laboratory quality controls all play a crucial role in detecting traces of food allergens. It is essential to follow each step, to ensure that accurate and reliable results are obtained.
Other than the sampling procedure, it is equally important to guarantee the integrity of the samples to be sent to the testing laboratory. This can be done by ensuring proper labelling of samples, maintaining storage temperatures as indicated by the manufacturer, and proper sealing of samples, to avoid contaminating other products or being contaminated by other samples.