1. Chemistry Of Cleaning & Sanitizing Generally soil and deposit are the same
terms define any organic, inorganic or
Science starts with definitions. mixture of organic and inorganic
compounds on a given surface.
Cleaning is the complete removal of soils
from surfaces. Cleaning processes are The primary source of soil is from the food
unnatural because all surfaces are product being handled. However, minerals
constantly being soiled. In order to get a from water residue and residues from
clean surface, it is necessary to work cleaning compounds contribute to films
against nature. left on surfaces. Microbiological biofilms
also contribute to the soil buildup on
The clean surface is defined as being free surfaces.
from soil, free from bad odours, be non-
greasy to the touch and have no visible Since soils vary widely in composition, no
oxidation. one detergent is capable of removing all
types. Many complex films contain:
Soil Identification combinations of food components, surface
oil or dust, insoluble cleaner components,
Soil1 is the state of being covered with and insoluble hard-water salts. These films
unclean things. vary in their solubility properties
depending upon such factors as heat effect,
Category Tree: age, dryness, time, etc.
state It is essential that personnel involved have
╚condition; status an understanding of the nature of the soil
╚sanitary condition
╚dirtiness; uncleanness
to be removed before selecting a detergent
╚ soil, dirt, filth, grime, stain, grease or cleaning regime. The rule of thumb is
that acid cleaners dissolve alkaline soils
(minerals) and alkaline cleaners dissolve
Soil2 is foreign matter that happens to be in acid soils and food wastes. Improper use of
the wrong place. For example, yogurt is detergents can actually "set" soils, making
food, but if it's poured on carpet, it is them more difficult to remove (e.g., acid
considered soil. cleaners can precipitate protein). Many
films and biofilms require more
Soil3 is any unwanted matter on the surface sophisticated cleaners which are amended
of an object that one desires to be clean. with oxidizing agents for removal.
Deposit is the phenomenon of sediment or The physical condition of the soil also
gravel accumulating. effects its solubility. Freshly precipitated
soil in a cool or cold solution is usually
Category Tree: more easily dissolved than an old, dried, or
baked-on deposit, or a complex film.
phenomenon
╚natural phenomenon
╚geological phenomenon
╚deposit, sedimentation, alluviation
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2. Cleaning Methods 3. Manual Cleaning
1. Clean-in-Place (C.I.P.) Removal of soil when the equipment is
totally disassembled. Soil removal is
Some parts of the processing machinery effected with chemical solutions and water
such as pipework, heat exchangers , tanks, rinses with the assistance of one or a
fillers etc. must be cleaned immediately combination of brushes, nonmetallic
after the production cycle has finished so scouring pads and scrapers, and high or
that when the next production cycle starts, low pressure hoses, with cleaning aids
the system should be cleaned. manipulated by hand.
C.I.P. signifies Cleaning In Place which Sanitization
means that the removal of soil from
product contact surfaces in their process When the surfaces are cleaned, visible soils
position by circulating, spraying, or are removed. But invisible soils such as
flowing chemical solutions and water bacteria, yeast, mold, etc. can continue to
rinses onto and over the surfaces to be living.
cleaned and the production equipment is
cleaned without being dismantled. It is a Sanitization is killing of microorganisms
totally automatic cleaning sequence with which are living on food contact or non-
no manual involvement. product contact surfaces.
CIP relies on the principal of applying a Cleaned surfaces can sanitized. For
suitable detergent or solvent at a suitable example before the using of hand sanitizer,
flow, pressure, temperature and you should wash your hand. Firstly soils
concentration for the correct length of on hands remove and then germs are
time. The science is based on applying the killed. Because soils can be nutrients for
required amount of energy to the germs and they can hide under soils.
equipment to ensure that it is cleaned. The
energy is primarily provided by the Sanitization includes 3 levels.
solution temperature (thermal energy), the
use of detergent or solvent (chemical 1. Sanitization
energy) and the application of suitable 2. Disinfection
pipeline velocities or pressures (kinetic 3. Sterilization
energy).
1.Sanitization
2. Clean-Out-of-Place (COP)
Sanitize refers to the reduction of
COP or in its full form, Cleaning Out of microorganisms levels considered safe
Place, is defined as a method of cleaning from a public health viewpoint. When we
equipment items by removing sanitize surface, we do not kill all
disassembled items from their operational vegetative bacteria or spores we only
area and taking them to the cleaning station reduce vegetative microorganism amounts
for cleaning. under safe level.
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3. 2. Disinfection Energy Equation For Cleaning
Disinfect refers to killing of all vegetative There’s actually an equation that
microorganisms. ( not spores ) determines the total amount of energy it
takes to properly clean something:
3.Sterilization
Sterilize refers to killing of all living
Mechanical Energy
organisms.
The official definition (Association of Thermal Energy Total Energy
Official Analytical Chemists) of sanitizing
for food product contact surfaces is a (Cleaning)
Chemical Energy
process which reduces the contamination
level by 99.999% (5 logs) in 30 sec.
The official definition (AOAC) for non- There are three types of energy that
product contact surfaces requires a combine to create a clean surface.
contamination reduction of 99.9% (3 logs). Mechanical energy comes from you,
The standard test organisms used are: scrubbing away. It is external forces.
Staphylococcus aureus and Escherichia While scrubing with sponge , you exert on
coli . soil to leave it on surfaces. Thermal energy
comes from the temperature of the
Water Chemistry and Quality cleaning solution. At the optimum cleaning
solution temperature alkali or acidic
Water comprises approximately 95-99% of cleaning solutions are more effective.
cleaning and sanitizing solutions. Their solubility and chemical activity
increase. Chemical energy is what the
Water functions to: chemicals in cleaning products bring to the
equation. Mechanical and thermal energy
 carry the detergent or the sanitizer vary with chemical energy.
to the surface
Detergents’ cleaning formulas provide
 carry soils or contamination from chemical energy through :
the surface.
 Wetting of the surface and soil
The impurities in water can drastically  Emulsification of oils
alter the  Saponification, or creating water
effectiveness of a detergent or a sanitizer. soluble soaps with basic or alkaline
Water hardness is the most important compounds
chemical property with a direct effect on
 Softening of water to neutralize the
cleaning and sanitizing efficiency. (Other
impurities can effect the food contact negative effects of calcium and
surface or may effect the soil deposit magnesium hard water
properties or film formation.)  Adding enzymes and/or bleach to
attack stains
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4.  Cleaning with solvents in c) Alkaline deposits such as films left by
combination with or in place of improper rinsing after use of an
water alkaline cleaner.
These factors are often used together to d) Minerals and rock formation. ( Sand,
maximize effects. I will mention these silt, clay )
factors next papers.
Oftentimes acidic cleaners are used to
There are 3 parameters that gets the dirty remove inorganic deposits. Minerals are
surface 100% clean which keeping the often cleaned with general purpose
balance with each other. For example if cleaners.
you don’t want to scrub very hard, but still
want the same Total Energy (cleaning), 1.2 Organic Soil
you need to raise either the Thermal energy
or the Chemical energy. Matter that once “lived” and that does
contain carbon.
Soil Classifications
a) Fat & Grease ( Body oils and animal
There are 3 main classifications of soils: fat )
1. Type of Soil b) Carbonhydrates & Proteins ( sugar,
honey, chocolate, jelly, chicken, milk,
2. Solubility Characteristics of Soil beef, … etc.)
3. Types of Cleaning Compounds c) Living matter ( mold, yeast, bacteria)
These classes are helpful about Most of the time organic soils are best
understanding cleaning processes. They removed using alkaline cleaners or
are parts of one part. solvents.
1. Type of Soil 1.3 Petroleum Soils
1.1 Inorganic Soil Motor oils, axle greases, wax, gums and
other products made from petroleum.
Matter that was never "alive", and thus These soils contain no water - in fact they
contain no carbon. repel water - and thus do not have a pH.
They often require another petroleum
a) Hard-water deposits such as water based solvent to remove them.
spots, calcium and magnesium
carbonates (Scale and lime deposits ) 1.4 Combination Soils
b) Metallic deposits such as rust, These are soils that contain an organic plus
corrosion, and oxidation. an inorganic soil and/or a petroleum
substances. These soils are difficult to
remove because they are hard to identify.
Proper identification is critical. Most
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5. combination soils are removed with a very minerals. Soils of this type present no
concentrated, highly built combination technical problem because their removal is
type cleaners - alkalines and solvents or merely a dissolving action. The greater part
acids and solvents. of food soil can either by suspended in
water or can simply be removed from a
surface by the force of a water spray. Any
soils not directly soluble in water will be
left behind as a thin film or as a deposit.
2.2 Acid-soluble Soils
Acid-soluble soils are soluble in acidic
solutions with a pH below 7.0. Deposits
It is important to select the appropriate include films of oxidized iron (rust), zinc
solvent and the correct cleaning compound carbonates (ZnCO3), calcium oxalates
for removing a specific soil. An acid- [Ca(COO)2], metal oxides (iron and zinc)
cleaning compound is most appropriate for on stainless steel, waterstone (reaction
the removal of inorganic deposits. An between various alkaline cleaners and
alkaline cleaner is more effective in chemical constituents of water having
removing organic deposits. If these classes noncarbonate hardness), hard-water scale
are subdivided, it is easier to determine the [Calcium carbonates (CaCO3) &
specific characteristics of each type of soil Magnesium carbonates (MgCO3) ], and
and the most effective cleaning compound. milkstone (a waterstone and milk film
Table 1–1 gives a breakdown of soil interaction, precipitated by heat on a metal
subclasses surface).
Table 1-1 Classification of Soil Deposits 2.3 Alkali-soluble Soils
Type of Soil Soil Subclass Alkali-soluble soils are basic media with a
Hard-water deposits pH above 7.0. Fatty acids, blood, proteins,
Metallic deposits and other organic deposits are solubilized
Inorganic soil
by an alkaline solution.
Alkaline deposits
Food deposits 2.4 Insoluble Soils
Organic soil Petroleum deposits
Nonpetroleum Soils insoluble in the cleaning solution are
deposits insoluble throughout the range of normal
cleaning solutions. However, they must be
2. Solubility Characteristics of Soil loosened from the surface on which they
are attached and subsequently suspended in
2.1 Water-soluble Soils the cleaning media.
These soils will dissolve in tap water and
in other solvents that do not contain a
cleaning compound. They include many
inorganic salts, sugars, starches, and
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6. Table 1-2 Solubility Characteristics of Soap & Detergent Chemistry
Food Soils
To understand what is needed to achieve
Surface Deposit Solubility effective cleaning, it is helpful to have a basic
knowledge of soap and detergent chemistry.
Sugar Water-soluble
Fat Alkali-soluble As you know water comprises approximately
Protein Alkali-soluble 95-99% of cleaning and sanitizing solutions.
Starch Water & Alkali
Soluble Water functions to:
Monovalent Salts Water & Acid
 carry the detergent or the sanitizer to the
Soluble surface
Polyvalent Salts Acid Soluble
 carry soils or contamination from the
surface.
3. Types of Cleaning Compounds
Water has a property called surface tension.
Soil deposits are characteristically complex In the body of the water, each molecule is
in nature and are frequently complicated surrounded and attracted by other water
by organic soils being protected by molecules. However, at the surface, those
deposits of inorganic soils, and vice versa. molecules are surrounded by other water
molecules only on the water side. A tension is
Therefore, it is important to identify created as the water molecules at the surface
correctly the type of deposit and to use the are pulled into the body of the water. This
most effective cleaning compound or tension causes water to bead up on surfaces,
combination of compounds to effectively which slows wetting of the surface and inhibits
remove soil deposits. It is frequently the cleaning process.
essential to utilize a two-step cleaning
procedure that contains more than one
Cleaning compound to remove a
combination of inorganic and organic
deposits. Table 1–3 illustrates the types of
cleaning compounds applicable to the
broad categories of soil.
Table 1-3 Types of Cleaning Compounds
for Soil Deposits
Type of Soil Required Cleaning
Compound
Inorganic soil Acid-type cleaner
Molecules inside a water drop are attracted in
Organic soil
all directions. Drops on the surface are
Nonpetroleum Alkaline-type attracted to the sides and inwards.
cleaner
Petroleum Solvent-type
cleaner
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7. After raining you can see surface tension a
drop of water onto a branch. The drop will hold
its shape and will not spread.
In the cleaning process, surface tension must
be reduced so water can spread and wet Different wetting states of a droplet
surfaces. Chemicals that are able to do this
effectively are called surface active agents, or
surfactants. They are said to make water
"wetter."
SOAPS
Soaps are produced during the chemical
Consider a liquid droplet at rest on a flat, solid
reaction known as saponification which is the
surface. The angle formed by the solid surface
reaction between a fat or oil and a base (strong
and the tangent line to the upper surface at the
alkali), producing glycerol and a salt (soap)
end point is called the contact angle(θ).
fat or oil + base -----> glycerol + salt (soap)
Soaps are usually sodium or potassium salts of
long-chain fatty acids.
Soaps are detergents in the sense that they
help clean oily and greasy dirt from fabrics,
The contact angle is a result of the metals, our skin and hair. We restrict the term
interface/surface tensions (surface free soap to the sodium salts of long-chain
energies) between liquid and solid surrounded carboxylic acids. A carboxylic acid is marked
by vapor. by the presence of a carboxyl group, -CO2H.
With the anion of the carboxyl group balanced
Measurement of the contact angle of a water
by a sodium cation and tied by a covalent bond
droplet is a quick and simple way to evaluate
to a long chain of -CH2- groups that terminate
cleanliness of a solid surface as below:
in a CH3- group, we have a soap molecule. We
can generalize the molecular structure of a
soap molecule as
CH3 - (CH2)n - CO2 - Na2+
CH3 - (CH2)n - resembles quite closely the long
chains of the hydrocarbon molecules. Like the
molecules of gasoline and mineral oil, this part
of the soap molecule tends to dissolve readily
From the contact angle, physical properties of in materials that are or that resemble
interaction between solid and liquid like hydrocarbons, but not in water. All these long
wettability, affinity, adhesiveness and chains of -CH2- groups of soaps and of
repellency can be studied. Typical evaluations hydrocarbons and hydrocarbon-like materials
are as shown below:
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8. intermingle easily, but they don't mix readily In a triglyceride molecule, three fatty acid
with the H2O molecules of water. The other molecules are attached to one molecule of
end of the molecule, though is ionic: glycerine. There are many types of
triglycerides; each type consists of its own
O particular combination of fatty acids.
||
+
-C - O - Na Fatty acids are the components of fats and oils
that are used in making soap. They are weak
Like sodium acids composed of two parts:
chloride and
other ionic A carboxylic acid group consisting of one
compounds, that hydrogen (H) atom, two oxygen (O) atoms, and
ionic end tends to one carbon (C) atom, plus a hydrocarbon chain
dissolve in water, attached to the carboxylic acid group.
but not in Generally, it is made up of a long straight chain
hydrocarbon of carbon (C) atoms each carrying two
solvents. As a hydrogen (H) atoms.
result, one
molecule has two
opposite and
contradictory
tendencies. A
hydrophilic
structure is
attracted towards
Alkali (Base)
water molecules
but shun
An alkali is a soluble salt of an alkali metal like
hydrocarbons
sodium or potassium. Originally, the alkalis
and other oily
used in soapmaking were obtained from the
and greasy
ashes of plants, but they are now made
substances. A
commercially
hydrophobic
structure shuns
water but mixes The common alkalis
easily with those used in soapmaking are
very oily, greasy sodium hydroxide
substances that (NaOH), also called
repel the caustic soda; and
hydrophilic, or potassium hydroxide (KOH), also called
charged, part. caustic potash.
How Soaps are Made
Fats and Oils Saponification of fats and oils is the most
widely used soapmaking process. This method
The fats and oils involves heating fats and oils and reacting
used in soapmaking them with a liquid alkali to produce soap and
come from animal water (neat soap) plus glycerine.
or plant sources.
Each fat or oil is
made up of a
distinctive mixture of several different
triglycerides.
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9. When the alkali is sodium hydroxide, a sodium
soap is formed. Sodium soaps are "hard"
soaps. When the alkali is potassium hydroxide,
a potassium soap is formed. Potassium soaps Step 2 Converts greasy and oily dirt into
are softer and are found in some liquid hand micelles that become dispersed in the soapy
soaps and shaving creams. water
The carboxylate end of the soap molecule is Now, as the hydrophilic heads of the soap
attracted to water. It is called the hydrophilic molecules remain surrounded by water
(water-loving) end. The hydrocarbon chain is molecules, the soap micelles break up and the
attracted to oil and grease and repelled by hydrophobic hydrocarbon tails, which had
water. It is remained in the interior of the spherical
known as the micelles, become embedded in the grease.
hydrophobic With this greasy dirt providing as compatible a
(water-hating) chemical environment for the hydrophobic tails
end. as the water provides for the hydrophilic
heads, the tails are just as much at home in
the grease as the heads are in the water.
Cleaning Action of Soaps
Step 3 Keeps the grease micelles in
Step 1 Decreases the water's surface tension, suspension, thereby preventing them from
making it a better wetting agent. coalescing back to large globules of grease
that could be redeposited on a clean surface.
Soap first lowers suface tension so that the
water carrying the micelles, clusters of soap Agitation now breaks the grease into
molecules in which the hydrocarbon chains are micelles whose surfaces are covered by the
attracted to each other by Van der Waals negatively charged carboxylate groups, the
forces (dispersion forces, London forces, weak hydrophilic -CO2- groups of the embedded
intermolecular forces), can get to the dirt. soap molecules. The grease droplets repel
When the soap micelles reach the embedded each other and remain suspended in the wash
dirt, the soap molecules that form these water instead of coalescing and redepositing
micelles once again find themselves at a on the material being cleaned. In the end, the
surface suspended droplets go down the drain with the
wash water. (While all this is going on the
sodium ions move about freely and
independently in the wash water.)
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10. an insoluble precipitate known as soap film or
scum.
Soap film does not rinse away easily. It tends
to remain behind and produces visible deposits
on clothing and makes fabrics feel stiff. It also
attaches to the insides of bathtubs, sinks and
washing machines.
Some soap is used up by reacting with hard
water minerals
to form the film.
This reduces
the amount of
soap available
for cleaning.
Even when
As a cleaning agent, soap suffers from two clothes are
main drawbacks: washed in soft
water, some
1. It does not function well in acidic solutions hardness
because of the formation of insoluble fatty acid. minerals are
introduced by
- +
the soil on
CH3(CH2)16COO Na (aq) +HCl(aq) clothes. Soap
molecules are
not very
+ -
versatile and
CH3(CH2)16COOH(s) + Na (aq) + Cl (aq) cannot be
adapted to
today's variety
2+
2. It forms insoluble precipitates with Ca and of fibers, washing temperatures and water
Mg2+ ions present in hard water, forming a conditions.
scum .
Synthetic detergents are increasingly being
- + 2+ used instead of soaps because they do not
2CH3(CH2)16COO Na (aq) + Ca (aq)
suffer from these disadvantages to the same
extent.
- 2+ +
[CH3(CH2)16COO ]2Ca (s) + 2Na (aq)
Additives such as sodium carbonate and
phosphates can help offset these effects.
How Water Hardness Affects Cleaning
Action
Although soap is a good cleaning agent, its
effectiveness is reduced when used in hard
water. Hardness in water is caused by the
presence of mineral salts - mostly those of
calcium (Ca) and magnesium (Mg), but
sometimes also iron (Fe) and manganese
(Mn). The mineral salts react with soap to form
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