be increased through increased temperature
of the cleaning compound and water or
high-pressure spray, which can aid in cutting
heavy soil deposits from the surface.
The second subprocess is soil dispersion in
the cleaning solution. Dispersion is the dilu-
tion of soil in a cleaning solution. Soil that is
soluble in a cleaning solution is dispersed if
an adequate dilution of cleaning medium is
maintained and if the solubility limits of the
soil in the media are not exceeded. The use of
fresh cleaning solution or the continuous
dilution of the dispersed solution with fresh
solution will increase dispersion.
Some soils that have been loosened from
the surface being cleaned will not dissolve in
the cleaning media. Dispersion of insoluble
soils is more complicated. It is important to
reduce soil to smaller particles or droplets
with transport away from the cleaned sur-
face. In this application, mechanical energy
supplied by agitation, high-pressure water, or
scrubbing is needed to supplement the action
of cleaning compounds in breaking down
the soil into small particles. A synergistic
action of the energy reduction activity of the
cleaning compound and the mechanical
energy can break the soil into small particles
and separate it from the surface.
The last subprocess is the prevention of
redeposition of dispersed soil. Redeposition
can be reduced by removal of the dispersed
solution from the surface being cleaned.
Other reduction methods are continued agi-
tation of the dispersed solution while still in
association with the surface to stop settling
of the dispersed soil; prevention of any reac-
tion of the cleaning compound with water
on the soil (note that soft water containing
sequestering agents will reduce the possibil-
ity of forming hard-water deposits from
soap present in the cleaning compound or
formed through fat saponification); elimina-
tion of any residual solution and dispersed
soil that may have collected on the surface
by flushing or rinsing the cleaned surface;
and maintenance of soil in a finely dispersed
condition to avoid further entrapment on
the cleaned surface.
Adsorption of surface-active agents on
the surface of soil particles causes similar
electrical charges to be imparted to the par-
ticles. This condition prevents aggregation of
larger particles because like-charged parti-
cles repel each other. Surface redeposition is
minimized because a similar repulsion exists
between surfactant-coated particles and the
surfactant-coated clean surface.
A systems approach to cleaning encom-
passes equipment for mechanical energy,
cleaning compounds to reduce the energy
holding the soil to the surface, and sanitizing
compounds to destroy microbial contamina-
tion associated with soil deposits. Successful
soil removal depends on cleaning proce-
dures, cleaning compounds, water quality,
high-pressure application of the cleaning
media, mechanical agitation, and tempera-
ture of cleaning compounds and media.The Role of Cleaning Media
Wateris the cleaning medium most fre-
quently used for soil removal. Other cleaning
media may include airfor removal of pack-
aging material, dust, and other debris where
water is not an acceptable cleaning medium.
Additional media may include solvents,
which are incorporated in the removal of
lubricants and other similar petroleum prod-
ucts. The primary water requirements for
food processing operations are that it must
be free from disease-producing organisms,
toxic metal ions, and objectionable odors
and taste. Since food processing establish-
ments do not normally have an ideal water
supply, cleaning compounds must be tai-
lored to the individual water supply and type
of operation.
The major functions of water as a cleaning
medium include:Cleaning Compounds 145