Handbook of Hygiene Control in the Food Industry

Disinfection can be performed by using physical (steam, ultraviolet,
irradiation)or chemical methods. In general,physicalmethodsare preferred
as theyare very reliable and leaveno residues behind. However, physical
methodscannotalwaysbe applied owingto restrictionssuchas temperature,
safety of personnel and designof the equipment.In those cases chemical
disinfectants are used(Krop, 1990).
In this chapterthe modeof actionof the maindisinfectants, the behaviour/
responseof pathogenicbacteria towards chemical disinfectants and some future
developmentsare discussed. The effect of physicalmethodsis not discussed.

4.2 Factorsinfluencingthe effectivenessof cleaningand

disinfection

A widerangeof disinfectants is availablethat can be dividedin the following

groups(see also Table4.1):

∑ halogen-releasing agents(HRA);

∑ quaternaryammonium compounds(QAC);

∑ peroxygens;

∑ alcohols;

∑ aldehydes;

∑ (bis)phenols;

∑ biguanides.

Eachof the differentgroupshas its ownapplicationswithin the foodindustry

and its own restrictions in use. It is importantto realisewhatthe proposedeffect

of a disinfectantis on a target-organismand whatpossible protection mecha-

nismsare present withinthe organism.In the following sections,the different

compounds,theirmodeof actionand theirapplicationsare discussed.

Table4.1 Disinfectantsand theirmodeof action

Biocide Modeof action Target

Halogen-releasingagents Halogenation/oxidation Nucleicacids,proteins

Quaternaryammonium Electrostatic(ionic) Cellsurface,enzymes,

compounds(QACs) interaction proteins

Peroxygens Oxidation Lipids,proteins,DNA

Alcohols(ethanol) Proteindenaturation Plasmamembrane

Aldehydes Alkylationreaction Cellwall

(bis)Phenols Penetration/partition Phospholipidbilayer

phospholipidsbilayer

Biguanides Electrostatic(ionic) Cytoplasmicmembrane

interaction (bacteria)/plasma

membrane(yeasts)

70 Handbookof hygiene controlin the foodindustry