shouldbe realisedthat in foodenvironments thereis oftenlittlevalue in tryingto
directlycorrelate surfacecounts to ATPreadings.For a strongcorrelation,the
ratiobetween microbial ATPand fooddebriswouldneedto be constant.Thisis
unlikelyto occurin many foodpremisesand sites,withthe possible exception of
somehandcontact surfaces (Griffithet al., 2000).It is possibleto havefood
Table36.2 Comparisonof microbiologicaland non-microbiologicaltesting
Attribute Microbiological
(cultivation)
ATP Protein
Acceptance Widelyaccepted
by foodindustry
worldwide.
Althoughnot
universally
accepted,it is
widelyacceptedin
the UK and many
othercountries.
Acceptancehas
increasedrapidly
since1995.
Generallyless well
acceptedthanATP
but morerecently
developed
technique.
Method/principle
testing
Microorganisms
derivedfrom
surfacegrowand
multiply.
Laboratory
facilities,or at
minimum,portable
incubationand safe
disposalsystems
required.
ATPderivedfrom
microorganisms
and fooddebris
convertedinto
lightand detected
usinga
luminometer.No
laboratoryfacilities
needed.
Proteinfrom
surfacefooddebris
transferredontoa
swabor equivalent.
Proteindetectedby
a colorimetric
reactionand
comparedwith
colourstandards.
No instrumentation
or laboratory
facilitiesrequired.
Timefor results 18±48hours. 2 minutes. 5±10minutes.
Reproducibilityfor
raw milk
contaminatedsurface
CV 84±300%. CV 9±79%. Not applicable.
Approximaterunning
costs
60±100pence
(in-house).
95±155pence. 95±145pence.
Capitalcosts Variablebut
incubator£130±
2000
Autoclave£600±
10,000.
Luminometer
£900±2500.
Optional
colorimeter
availablefor some
tests.
Staffrequirements Somelevelof
microbiological
training.
Brieftrainingin
test protocol.No
specialised
knowledge
required.
Brieftrainingin
test protocol.No
specialised
knowledge
required.
Improvingsurfacesamplingand detection of contamination 595