Use of technology according to purpose

DNA detection methods such as polymerase chain reaction or PCR may not indicate the presence of allergenic proteins, so a negative PCR result does not guarantee the absence of proteins.

For this reason, the use of protein or peptide detection methods is preferable, although the European Directive 2007/68/EC states that all food allergen derivatives contained in the product must appear on the label, without distinguishing between proteins or other compounds such as metabolites or DNA.

Recommended technologies for typical applications: Because it is a quantitative technique, enzyme-linked immunosorbent assay (Elisa) analysis is recommended for verification of cleaning processes or for testing of components or finished products.

Lateral flow devices or LFD's can be used on site for routine cleanliness verification checks, but should be confirmed on a regular basis by ELISA analysis.

If the result of the protein-based method is ambiguous, the result obtained from the PCR test can be used as an auxiliary confirmation. However, given the sensitivity of the PCR test to certain allergens, this would be acceptable when the ELISA result is greater than 10-20 mg/kg (ppm).

The use of the PCR test is only recommended when no other protein-based detection technology is available, such as for the detection of nuts other than walnuts, hazelnuts or almonds or for the detection of celery.

LFDs should be used on-site, for routine cleanliness verification inspections or for testing for the purpose of a finished product release.

Mass spectrometry (MS) methodology is not a conventional technique and should be used if results obtained with conventional methods are divergent, and a second confirmatory test is required.

Methods based on protein detection:

• Protein is the main target in detection, because most of the food allergens listed in appendix iii of directive 2007/68 /ce are proteins, except sulfite and sulfur dioxide.

Methods based on protein detection can be divided into two categories.

Immunological methods:

• This type of method is based on antibodies. An antibody, similar to the one that causes allergic reaction in humans, is used to detect proteins.

• Typical methods are the enzyme-linked immunosorbent assay (ELISA) and lateral flow devices (LFD) known as test strips.