acetic acid and QAS, it can be cost-re-strictive to small enterprises.
Ozone is a potent sanitizer, albeit
very unstable, so it consequently must
be generated onsite. In addition to the
relatively high cost of the generator, the
solubility of ozone is low with saturation
occurring between 3–5 ppm, although
Sanitizer Disadvantages
Condensing steam • Only applied to localized areas
• Requires application in
combination with physical force
(i.e., pads or brushes)
• Denatures proteins (greater
adhesion to surfaces)
• Expensive
• Long contact times required
• Denatures protein
• Expensive
• Stable in hard or soft water by-products
• No generation of resistant • pH-dependent
mutants • Corrosive
• Widely applied • Sequestered by organics
• Inexpensive • Hazardous to handle
• Generates chlorine gas if mixed
with acid
Chlorine dioxide • Hazardous to handle
• Degraded at temperatures >50 °C
• Sensitive to light
• Expensive
• Greater oxidation power
compared to bleach
Iodine • Active at low concentrations • Decomposes under alkaline pH
• Less affected by organics • Stains surfaces
• Stable in hard or soft water • Poor solubility in water
• Active against viruses
Quarternary • Active in broad temperature
ammonium salts range
• Less affected by organics
• Active under alkaline pH
• Residual activity (non-post-
rinse sanitizer)
Ionic (inorganic acids • Compatible with low pH
with surfactant) • Unaffected by water
hardness
• Non-corrosive
• Low odor generation
Advantages
• Chemical-free
• Non-corrosive
• Chemical-free
• Penetrates crevices
• Easy to apply
• Minimal generation of
by-products
• Applied at low
concentrations
higher concentrations can be achieved if
the gas is applied under pressure. Once
applied, ozone depletes over a 15-
minute period but is more rapidly depleted in the presence of organics. New
innovations in ozone technology include the development of units to generate aqueous solutions containing
nanobubbles of the strong oxidizing gas.
It is well established that nanobubbles are effective at stabilizing gas in solution due to surface tension effects.
However, the effect is only observed
when the bubbles are in nanometer
scale. In the case of ozone, bubble size is
reportedly in the micrometer range, so
one can predict that stability would be
compromised. In addition, nanobubbles
would not improve stability of ozone in
the presence of organics. There have
been no independent studies of the sanitization efficacy of nanobubbles compared to conventional ozonated water.
• Sequestered by surfactants
• Unstable in hard water unless
chelating agent is applied
• Residual activity (fermentation
failure)
Table 2: Types of Sanitizing Agents Applied in Plant Sanitation
• Only active within pH 2–3
• Ineffective against yeast and mold
• Foams
• Sequestered by cationic surfactants
• Expensive
• Residual activity
• Low activity in pH > 4
• Ineffective against yeast and mold
• Corrosive to metals and plastics
• Residual activity
• Broad spectrum • Pungent odor
antimicrobial activity • Unstable under alkaline pH
• Non-foaming • Expensive
• Active at low concentrations
• Stable in organics
• Effective against biofilms
• Biodegradable
Ozone • No chemical residue • Unstable
• Low by-product • Rapidly sequestered by organics
generation • No residual activity
• Broad range of antimicrobial • Expensive
activity
Fatty acids
(carboxylic acids)
• Stable in organics and
high temperatures
• Low foaming
Peroxides
(peroxyacetic acid)
Verification of Procedures
Upon completion of sanitation, there
is a need to verify (confirm) that the procedures have been effective. The simplest approach is to undertake a visual
assessment to ensure that no debris remains and standing water has been removed. Of course, visual assessment
cannot be used to estimate the microbial
loading of the sanitized surface. It is possible to indirectly assess the efficacy of
sanitation by performing protein residue
tests. Although cheaper and more rapid
than microbiological testing, the sensitivity of the test is low. In contrast,
adenosine triphosphate (ATP) testing is
both rapid and sensitive, although it is
more costly than microbiological testing.
Microbiological testing can be performed using prepared contact plates
that are pressed onto surfaces to collect
microbes and incubated prior to colony
counting. Swabs can also be used in
combination with dehydrated agar
plates. Here, the swab is pre-wetted and
streaked over the contact area surface.
The choice of microbes to screen for
is dependent on the types of food products produced. Total aerobic counts provide a general assessment of the bacterial
populations present. Fecal indicators (
Escherichia coli, coliforms and Enterobacte-riaceae) provide information on the
