usedin foods, suchas colourscould obviously also interfere withthe per-
formance of assaysbasedon colorimetric end-points,depending on theirfate
during extraction.Changesto proteins due to processing
Food processingprobablyposesthe greatest challengeswithrespect to allergen
detection, particularly for the most common type of assay, namely
immunoassays. Processingcan altereitherthe allergenicityof a protein,or its
ability to be detected in the food matrix, either because of changes in
immunoreactivityor in the interactionsbetween the protein and the matrix, or
indeed both.Thus,fermentationof milkwithcertainstrains of lactobacilli
reduces the IgE-bindingcapacityof the productcompared withnativemilk,
suggesting a reduction in its ability to provoke reactions. Under these
circumstances, detectionof loweramountsof milk protein wouldbe a true
reflectionof a reduction in hazardto the allergic individual.A similar situation
occurs in the caseof the appleallergen,whichis knownto be heat-labile.^19
However, assayscan also significantly underestimate the contentof heat-treated
milkproteins,as a resultof what mustbe assumedto be altered recognition of
the protein analyte, since a total protein assay yielded total recovery
(unpublishedresults). Similar findingswere reported by Koch et al.^20 for
roasted peanutproteins.Clinical dataon reactivityto heatedmilkand peanut
proteinssuggest that under thosecircumstancesthe apparent reduced protein
content doesnot reflect a reduction in hazardto the allergicperson.These
examples illustrate the needfor a thoroughunderstandingof the pitfalls of an
assay before it is usedto generate datathat will be usedin risk assessment.
23.5 Futuretrends
The needfor detectionof allergenic residues has nowbeenestablished as the
importance of food allergy as a public health problem has become
acknowledged.Several current trendsare likely to influencethe development
and application of allergendetection.Oneis the developing legalframework,
whichwill ultimately lead to defined actionlevels. Anotheris the determination
of NOAELs for manyof the mainallergenic foods. A thirdmaybe the needfor
ways of monitoringallergenicity of particular foods, as theyare modified to
reduce theirallergenicity.Finally, whileit not currentlyfeasible, pressurefrom
allergic peopleand theirsupportgroupsfor the meansof monitoring foodsfor
the presenceof cross-contactallergensmaylead to developmentof some rapid
assays. The likely influenceof eachof thesetrends will be examined separately.
The legal frameworkwithrespect to foodallergensis developingfast,with
Switzerland,Japan,Australia/NewZealand and the European Unionbringing in
legislationspecifying whichallergenicfoodsmust be declared. Thelistsare
usually based on the list of allergensin the Codex General Standard on
Labelling,but extendit to coverallergensof regionalimportancesuchas celery
374 Handbookof hygiene controlin the foodindustry