easily than are Bacillus spores. Chlorine
concentrations of less than 50 ppm lack
antimicrobial activity against Listeria mono-
cytogenes, but exposure to more than 50
ppm of this sanitizer effectively destroys this
pathogen. This lethal effect of most chlorine
compounds is enhanced, with an increase in
free available chlorine, a decrease in pH, and
an increase in temperature. However, chlo-
rine solubility in water decreases and corro-
siveness increases with a higher temperature,
and solutions with a high chlorine concen-
tration and/or low pH can corrode metals.
Chlorine compounds have the following
advantages over other sanitizers:
●They are effective against a variety of
bacteria, fungi, and viruses.
●They include fast-acting compounds
that will pass the Chambers test at a
concentration of 50 ppm in the required
30 seconds.
●They are the cheapest sanitizers (if
inexpensive chlorine compounds are
used).
●Equipment does not have to be rinsed if
200 ppm or less is applied.
●They are available in liquid or granular
form.
●They are unaffected by hard-water salts
(except when slight variations, due to
pH, exist).
●High levels of chlorine may soften gas-
kets and remove carbon from rubber
parts of equipment.
●Toxic by-products are not produced.
●They are less corrosive than chlorine.However, they have some disadvantages:
●They are unstable and drive off rather
rapidly with heat or contamination with
organic matter.
●Their effectiveness decreases with
increased solution pH.
●They are corrosive to stainless steel and
other metals.●They must be in contact with food-han-
dling equipment, especially on any type
of dishes, for only a short time to pre-
vent corrosion.
●They deteriorate during storage when
exposed to light or to a temperature
above 60°C.
●Solutions at a lower pH can form toxic
and corrosive chlorine gas (Cl 2 ).
●Concentrated in the liquid form, they
may be explosive.
●Chlorine is irritating to the skin and
mucous membranes.
●The environmental impact is question-
able because of the formation of poten-
tially toxic organochlorine by-products.
This concern is based on research results
that indicate chlorine reacts with natu-
rally occurring organic materials pri-
marily humic acids, and water which
result in the formation of suspected car-
cinogenic trihalomethane compounds
(Anon., 2003).Iodine Compounds
The mode of antibacterial action of
iodine has not been studied in detail. It
appears that diatomic iodine is the major
active antimicrobial agent, which disrupts
bonds that hold cell proteins together and
inhibits protein synthesis (Anon., 1996). Gen-
erally, free elemental iodine and hypoiodous
acid are the active agents in microbial destruc-
tion. The major iodine compounds used for
sanitizing are iodophors, alcohol-iodine
solutions, and aqueous iodine solutions. The
two solutions are normally used as skin dis-
infectants. The iodophors have value for
cleaning and disinfecting equipment and sur-
faces, and as a skin antiseptic. Iodophors are
also used in water treatment.
The iodophor complex releases an interme-
diate triciodide ion, which, in the presence of
acid is rapidly converted to hypoiodous acid