5 Fundamentals of Allergen Analysis #3: Choosing the appropriate method of analysis

Allergen surveillance plays a key role within any allergen management plan. Whether setting the plan in place or carrying it out, we need methods of allergen detection. This helps us not only to evaluate the measures we need to apply but also to verify the effectiveness of the plan and, of course, to monitor the allergen status of all ingredients, materials and products. It is therefore essential that the methods selected to check for allergens are well suited to our purposes. 

It is tempting to think that choosing a method should be as simple as finding one that detects the allergen of interest and has a reasonably low limit of detection. No matter whether you intend to perform the method in-house or send your samples to an external laboratory, there is more to it than just picking one with a low LOD.

Do you need quantitative or qualitative results for your food allergen tests?

The first thing to determine is whether you need qualitative or quantitative results. This will depend on the purpose of the test. It is also important for the simple reason that qualitative methods are usually faster and more economical than qualitative ones. If you have set a certain value for the amount of allergen acceptable in a certain material, a qualitative method might be enough during routine testing. Both qualitative and quantitative methods can help you validate the procedure.

It is important to check what the actual analyte of the method is. Though the aim of a method may be to determine a particular allergen, the actual analyte is sometimes just part of that allergen; for example, instead of detecting milk, the method will actually detect only casein or beta-lactoglobulin. Make sure you understand the implications for your product and confirm that the detection of this analyte is appropriate.

Determine the LOD and LOQ for your method with the portion size of your product in mind!

Be sure to determine the actual LOD and LOQ of the method for your specific matrix. Some matrices present LODs significantly different from the ones stated in the method’s instructions. This is because, in most cases, that value corresponds to the LOD in blank buffer. 

If you are using allergen threshold levels as guidance, there is an extra layer of complexity: you first have to determine the LOD and LOQ for the portion size of your product. Leaving aside that there are no universal thresholds and that values might vary by 100-fold from guideline to guideline, a simple example will elucidate this problem: the portion size for some cookies is around 20 g while that for a cereal bar could be closer to 200 g. If you were to check the egg content of these products, you might need LODs/LOQs of 215 ppb or 21.5 ppb, respectively. Thus, a method suitable for one product won’t do the trick for the other.

Finally, and as previously described, the matrix can present challenges that affect the recovery of the allergen. Be sure you pick a method that provides a percentage of recovery within a previously defined, acceptable range for your matrix (usually 60-140 % is recommended for food allergens), and adjust your acceptance criteria accordingly.