5 NaClO 2 +4HCl→4 ClO 2 +5NaCl
+2H 2 O
NaOCl+HCl→NaCl+HOCl
HOCl+2NaClO 2 →ClO 2 +2NaCl+H 2 OMeinhold (1991) reported that ClO 2 is
being used in cleaning and sanitizing
through foam generation. This sanitizer
can be produced through combining chlo-
rine salt and chlorine or hypochlorite and
acid, followed by the addition of chlorite.
Biodegradable foam containing 1- to 5-ppm
ClO 2 can be produced and is effective with a
shorter contact time than the quats or
hypochlorites. Chlorine dioxide is effective
against a broad spectrum of microorgan-
isms, including bacteria, viruses, and spore-
formers. As a chemical oxidant, the residual
activity significantly inhibits microbial rede-
velopment. It is active over the broad pH
range normally encountered in food facilities
and more tolerant of organic matter than
chlorine. This compound is less corrosive
than other chlorine sanitizers because of the
low concentration necessary to be effective
and produces less “undesirable” chlorinated
organics. The major disadvantages of chlo-
rine dioxide include cost, difficulty of han-
dling, sensitivity to light and temperature,
and potential safety and toxicity limitations.
The U.S. Food and Drug Administration
(FDA) has approved the use of stabilized
chlorine dioxide for sanitizing of food pro-
cessing equipment. Anthium dioxide is a
compound with 5% aqueous solution of sta-
bilized chlorine dioxide supplied with a pH
of 8.5 to 9.0. Free ClO 2 is the potential bio-
cidal agent in the solution. Although
anthium dioxide does exhibit bacteriostatic
properties, it is not nearly as effective as free
ClO 2. The active biocide is free ClO 2 , even
though the stabilized ClO 2 at pH 8.5, is
mildy bacteriostatic. The anthium dioxide
complex is a combination of oxygen and
chlorine joined as ClO 2 in aqueous solution,
which provides a longer residual effect than
other chlorine sanitizers. Industrial applica-
tions include a no-rinse sanitizer at 100 ppm,
poultry chill tanks at 3 to 5 ppm, and drink-
ing water treatment.
Oxinehas gained recent interest as a sani-
tizer. It differs from generated ClO 2 as it is
formulated from scratch, using a proprietary
process, as opposed to being converted from
chlorite. Increased microbial kill is possible
by adjusting the ratio of chlorite and chlorine
dioxide, and of other oxychlorine species,
through the formation of oxine. Oxine is sta-
bilized through dissolving it into a propri-
etary aqueous solution and essentially
converting it into its “salt” form (Flickinger,
1997). An activator, such as food-grade acid,
is needed for this binary product to lower the
pH and retrieve the gas. The major applica-
tion of this compound is as a surface sani-
tizer that is effective against biofilms. Recent
testing conducted with E. coli O157:H7
revealed that oxine destroys this pathogen at
6 ppm (Flickinger, 1997).
Acidified sodium chlorite (ASC), and
antimicrobial agent generated by mixing
concentrated sodium chlorite solution with
a generally-recognized-as-safe acid at
sodium chlorite concentrations of 500 to
1200 ppm, is approved by the U.S. Food
and Drug Administration for use with poul-
try, red meat, comminuted meat products,
and processed fruits and vegetables to
reduce bacterial contamination. It is also
approved by EPA as a pesticide for use on
food contact surfaces. This sanitizer can also
be incorporated in water or ice at concentra-
tions of 40 to 50 ppm to wash, rinse, thaw,
transport, or store seafood.
When chlorine compounds are used in
solutions or on surfaces where available
chlorine can react with cells, these sanitizers
are bactericidal and sporicidal. Vegetative
cells are more easily destroyed than are
Clostridiumspores, which are killed moreSanitizers 173