23.4 Roleof allergendetectionand otherconsiderations
23.4.1 Whydo we needdetectionmethods?
Methodsfor the detectionof allergenic residues can be deployedfor a variety of
uses.In industry, these will includewhatis effectively the exposureassessment
part of risk assessment. Typical activities would be assessmentof the extent of
cross-contactat different points,as part of a HACCP study and subsequently
validation of the measuresput in place to controlthe extentof low level
homogeneouscross-contact.Extendingup the supply chain,suchmethodscould
also be usedto confirmsuppliers'statements abouttheiringredients,as part of
the audit of their processes, while downstream, product analysis could be
envisaged where incidents haveoccurred,or there is a suspicion that allergenic
residues mayexceed specification.Similarly, confirmationthatresidues are
present, and in what amount would be an important starting point for
investigation of incidents.However, industry is not the onlypotentialuserof
detection methods. Public authorities need to provideevidenceto support
compliance activities,and demonstrationof the presenceof residual allergen in
products whichare not supposed to containthemcan forma strongpart of such
evidence. Allergic consumers mayalso be potentialusers of suchmethods,
althoughnoneis currently suitablefor this typeof application.
Different users probably require different methods with different
characteristics,withrespect to detection limits,quantitation,robustnessand
ease of use.Riskassessment activities imply quantitative evaluations, and
requiremethodsthat measureaccuratelyand reliablythe residues of interest,
evenin complexmatrices. In HACCP studies, althoughdesirable, it is probably
not essential for the methodto be easy to use. In contrast, enforcement
authorities willonlyin practicebe interestedin quantitationif the relevant
regulations specifyan actionlevel.If no level is specified, it wouldpresumably
be sufficient for a methodto havean adequate detection limitand to be known
not to produce falsepositives.For potentialallergicusers,a key requirementis
no falsenegatives, as wellas an adequate limitof detection.
23.4.2 What shouldassaysfor allergenic residuesdetect?
The allergenicactivity of a foodusually dependson a rangeof proteins, and it
has beenshown many times that the pattern of responseof allergic people to the
different proteins can differ considerably.^12 It has also beenshown more
recentlyboth in allergicpatients^13 and in experimental animals^14 that the overall
responseto an allergenicfoodis a summationof the responses to the individual
proteins. The implicationof thoseobservationsis that immunoassays for food
allergensshould essentially be consideredas meansof quantitatingthe relevant
protein(s),ratherthan measuring allergenicactivity in the food,whichwill differ
for eachallergic patient.Anotherimplication is thatquantitation of single
allergenic proteins maybe valuable if one is tryingto monitor the effectof
processing on suchproteins,but may give highlymisleadingresults if usedin an
assaydirectedat otherpurposes, suchas the estimation of the extentof cross-
Managingrisksfromallergenicresidues 369