microorganism and establishingrisk are fundamentalto developingcoherent
science-based sanitization strategies.
It wouldbe idealif the yeast, molds,viruses,and bacteria,associated with
foodprocessing,respondedequallyto the variousmethodsof sanitization and
disinfection.The fact is, however, that theydo not. Amongthe bacteria, for
example, there is great disparity in susceptibility to chemical and heat
treatments.As a rule, Gram-positivebacteria tendto be moreresistant to heat
and chemicals thanare theirGram-negativecounterparts.Thisdisparityis evi-
dentevenwithin species: considerthatSalmonellaentericaserovarSenftenberg
(D 72 à0.09min)is severaltimes more resistantto heatthanisSalmonella
entericaserovar typhimurium (D 72 à 0.003 min) in the identical heating
medium (Adams and Moss,1995). This inequalitymust be takeninto account
before makinga decision regardingsanitization methods. Thermaland chemical
sanitizingare the preferredmethodsof the foodprocessing industry.
Thermalsanitization methods
Thermalsanitizing withhot wateris commonplacein COPcleaning operations.
Hot wateris a veryeffective broadspectrum sanitizer,disinfectant, or sterilant.
It is effectiveagainst yeast,molds, viruses,bacteria, and bacterial spores.
Achieving the desired lethality or level of inactivation is dependent on
temperature,pH, and exposure time.Hot wateris easilyappliedand has great
penetratingability. It is minimally corrosiveand therefore compatiblewiththe
widerangeof metals and plasticsusedin foodprocessing.Hot watersanitizing
is a slowprocess as it mustallowfor bothcome-upand cooldowntimes. Hot
watersanitizing also has the disadvantagesof forming or contributing to film
formation, and also shorteningthe life of certainequipment.As a general
recommendation,hot watersanitizingrequires a watertemperatureof 180 ÎF
(82 ÎC) witha minimumexposure timeof 20 min.
Chemicalsanitization methods
It is often writtenof the ideal chemical sanitizerthat it shouldbe approvedby
regulatoryofficials for foodcontactsurfaceapplication;it should havea wide
range or scopeof activity and rapidly destroy microorganisms. Theideal
sanitizermust also be stableat conditionsof use and storage. It should be soluble
and possess somedetergencywhilehavinglow toxicityand corrosivity. It will
become abundantly clearafteran evaluationof the chemicalsdiscussed in this
section that thereis no single compoundfor the job of sanitization.
Chemicalsanitization is somewhat more complicatedthanthermal methods.
As previously noted thereis greatdisparityin the responseand susceptibilityof
microorganisms to chemical treatments. The effectiveness of chemical
sanitizingis dependent on concentrationas deliveredand exposure time. Other
factors that may limit the effectiveness of chemical sanitizing include
temperatureand the presences of foodor detergent films.Surfacesthat contain
biofilmscannotbe effectivelysanitized.
458 Handbookof hygiene controlin the foodindustry