21.10.1 Heat-treated foods
Heat-treatedfoodsthat are designedto be microbiologicallystable mustbe heat
treated to an extent that will prevent the outgrowth of microorganisms underthe
conditions,includingpackaging,and duringthe period,in whichthe foodsare
intended to be stored.All low-acidfoodshavingin any part of thema pH value
of 4.5 or aboveand intended for storageundernon-refrigerated conditionsmust
be subjectedto the minimumbotulinumprocess, i.e. one that will reducethe
probabilityof survivalofClostridium botulinumsporesby at least12 decimal
reductionsunlessthe formulationor wateractivityor both,of the foodis such
that it can be demonstratedthat growth of strainsor formsof the organism
cannotoccur.21.10.2 Chilledfoods
Chilled foods, which offer high risk of potential growth of pathogenic
organisms,needthe moststringenthygieneprecautions.Product safety must
be determinedby the proper considerationof ingredients'hygienic quality,
product formulation/characteristics, processing parameters, intended use of
product, storage and distribution conditions, manufacturing hygiene and
intended shelf-life.
21.10.3 Frozenfoods
Frozen foodsare criticallydependent for theirsafepreservationon stringent
hygiene and carefulmaintenance of the coldchain,i.e. an organisedsystem
governingthe conditionsunderwhichfrozenfoodsare storedand handled by the
producer, distributor and retailer, and whichensure that temperaturesmaintained
during storage, distribution and sale are thoseconsistentwith the maintenance of
quality and safety.
21.10.4 Dryfoods
Dry foodsand processes involvingdry materials haveproblemsassociatedwith
dust, particularlythose of cleaning, the possible creationof an explosivedusty
atmosphere and the risks of cross-contamination by dust particles. It is
important,therefore,to containdust as far as possible in an enclosedsystemand,
withthe aid of dust removaland extraction systems, to maintain a highstandard
of cleanliness.The generalenvironmentof the plant and equipment including
ledges and girders, etc. shouldbe regularly cleaned and an effective air
extraction systemshouldbe installed. Such a systemshould discharge througha
filter and at a pointsituated so as to minimise the risksof the discharge being
ableto contaminateother plantor products. Dust extraction systems shouldbe
properly maintained,cleanedand serviced; theybecomeheavily coatedinside
duct-work,and cleaningand filterchanging can create a verydustyatmosphere.
Dusty atmospheresshould be considered as potentially dangerous explosion
338 Handbookof hygiene controlin the foodindustry