question whethertherecan be a single idealassay'equallysuitable for all purposes. Theidealassay'conceptwill therefore be examined in some of the
differentcontexts in whichit might be used.
Assaysfor monitoring effectiveness of allergen risk managementmeasures
A typicalapplicationof suchan assay wouldbe to assess effectively different
line cleaning measures,for instance. A primaryrequirementwouldbe that it is
sensitive enoughto detect relevant levelsof allergen,and that it possesses
adequate accuracy, providinga true measure of the analyte. A highdegree of
precisionis not as importantas accuracy, however. Highspecificity is alsoa
requirement,as foodproducts willoftencontain a numberof proteins from
differentsources.Detection of irrelevant proteins couldleadto inappropriate
decisionswithregardto allergen management,implementingmore stringent
measuresthan necessary, or leading to defensive labelling, if the analysis
suggests the problem cannot be overcome. However, in addition to the
appropriatetechnicalparameters,the assayalso needsto be designedfor those
whowillbe the primary users. In the factory environment,these will not
necessarilybe people withspecialised laboratorytraining.Theassaydesign
must therefore be sufficiently robustfor use by non-laboratorypersonnel,and
formats such as calibratedtest strips, for instance, are worthinvestigating.
Similarly,experience of the development of in-home diagnosticassaysusedfor
clinical monitoring mayholdvaluablelessons.
Assaysfor measuringresidualallergen in finishedproducts
Although measuring residual allergenin finishedproducts is not a common
applicationof assays,thereare occasions whenit is necessary.Thesemay be, for
instance, wherea processfailureleadsto the conclusion that thereis a high
probability of residual allergen beingpresentat a level likelyto endanger
allergic individuals, or where therehavebeenreportsof reactions to the product.
While this typeof applicationrequires of an assay many of the same properties
as described for monitoringassays,the assayis likely to be performedby
laboratorypersonnel,ratherthanin a factory,and therefore `user-friendliness',
whilealwaysdesirable, is of a lowerpriority.
Assaysfor investigating compliance
Where limits havebeenset on the residual allergen amountsin foodproducts,
the assaymust meetmorestringent requirementsin somerespects thanin the
previous instances.Sensitivityand specificityare key elements as before,while
precisionis moreimportantthanfor otherassays,giventhe potential legal
implicationsof the test detecting allergen. In particular, the assay should havea
low incidence of falsepositives.
Assaysfor measuringsingleallergenic proteins
Manyassayshavebeendeveloped for single allergenic proteins.Whilethese can
sometimes serve for the purposes described above, they have many
372 Handbookof hygiene controlin the foodindustry