microbiological quality of food-contact materials.For dairyproducts, the so-
called `Dairyman'sstandard' statesthe limitfor microbiological contaminants in
liquidpackagingmaterial (250cfu gˇ^1 ). TheFoodand Drug Adminstration
(FDA) standard (FDA, 1991)alsostates that microbial numbersshouldnot
exceed 1 cfu cmˇ^2 or 250 cfu gˇ^1. Thetotalnumbers of yeasts,mouldsand
bacteria accepted must be low,and no pathogenicbacteria,including entero-
bacteria andEscherichia coli, should be detected (May,1994).A German DIN-
10082 standard (1996)sets a limitof six yeastsand two mouldsdmˇ^2 for
greaseproofpaper.
Legalaspectsare important,but equally importantare the demandsand
requirementsset by the customers, the foodindustry, whichmost oftenare
clearly tighter thanthe legal onesand presupposean active Hazard Analysis
Critical Control Point (HACCP)programme to confirmthe safetyof paper
products usedin foodapplications.In additionthe hygiene and safetydemands
set by the company itselfto givethe impressionof a companythat considers
safety aspectsseriously havebecomean importantmarketing argument, e.g. in
the pulpindustry.
24.2 Potential microbiological problems withpackaging
Production of fibre-basedfoodcontact materials includeseveralphases in which
microbiological problemscan occur.However it mustbe stressed that the threat
of microbial contamination frompackagingmaterials is moretheoretical, while
fooditself is alwaysthe mostprominent source of microbial contamination.
There are no publishedcaseswhere microorganismsoriginatingfrompackaging
material havemigrated into the food,multiplied thereand causedillness of a
human. However there are cases when microorganisms originating from
packagingmaterials havespoiledthe foodproduct. Paperand boardmachines
offer microorganismsa favourableenvironmentto growand multiply,and hence
theirnumbers may be quitehighwithout causing significantproblems for
runnabilityor end-product safety. Therefore,it is moreimportantto determine
the natureof the microorganisms(e.g.pathogen,slime producer,toxinformer,
producer of off-odours)thantheirexactnumbers.
Microbiological problemsin the paperindustry can be grouped as follows:
∑ Microorganisms causing spoilage of raw materials, sincemany micro-
organismsbreak downcellulosefibres,starch,caseinand rosinsizings,e.g.
PantoeaagglomeransandBacillussubtilisspoil starch.
∑ Microorganisms causingproblems in the process: producers of slimeand
deposits, e.g.Burkholderiacepacia,Deinococcusspp. andBacillusspp.
∑ Microorganisms threatening process safety: microorganisms harmful to
human healthin raw materials,processenvironmentand end-products,e.g.
Bacillus cereus, KlebsiellapneumoniaeandStaphylococcus aureus.
∑ Microorganisms reducing the quality of end-product: microorganisms
harmful to human health and their metabolic products (toxins),
380 Handbookof hygiene controlin the foodindustry