D-1000 Cleaner / Sanitizer 20%
Glutaraldehyde solution.
Definitions
Cleaning
Cleaning is the complete
removal of food soil using appropriate detergent chemicals under
recommended conditions. It is important that personnel involved have
a working understanding of the nature of the different types of food
soil and the chemistry of its removal.
Cleaning Methods
Equipment can be categorized
with regard to cleaning method as follows:
-
Mechanical Cleaning.
Often referred to as clean- in-place (CIP) . Require no
disassembly or partial disassembly.
-
Clean-out-of-Place (COP).
Can be partially disassembled and cleaned in specialized COP
pressure tanks.
-
Manual Cleaning.
Requires total disassembly for cleaning and inspection.
Sanitization
It is important to
differentiate and define certain terminology:
-
Sterilize refers to
the statistical destruction and removal of all living organisms.
-
Disinfect refers to
inanimate objects and the destruction of all vegetative cells (not
spores).
-
Sanitize refers to
the reduction of microorganisms to levels considered safe from a
public health viewpoint.
Appropriate and approved
sanitization procedures are processes and, thus, the duration or
time as well as the chemical conditions must be described. The
official definition (Association of Official Analytical Chemists) of
sanitizing for food product contact surfaces is a process which
reduces the contamination level by 99.999% (5 logs) in 30 sec.
The official definition for
non-product contact surfaces requires a contamination reduction of
99.9% (3 logs). The standard test organisms used are:
Staphylococcus aureus
and
Escherichia coli .
General types of sanitization
include:
-
Thermal Sanitization
involves the use of hot water or steam for a specified temperature
and contact time.
-
Chemical Sanitization
involves the use of an approved chemical sanitizer at a specified
concentration and contact time.
Water Chemistry and Quality
Water comprises approximately
95-99% of cleaning and sanitizing solutions. Water functions to:
The impurities in water can
drastically alter the effectiveness of a detergent or a sanitizer.
Water hardness is the most important chemical property with a direct
effect on cleaning and sanitizing efficiency. (Other impurities can
effect the food contact surface or may effect the soil deposit
properties or film formation.)
Water pH ranges generally from
pH 5 to 8.5. This range is of no serious consequence to most
detergents and sanitizers. However, highly alkaline or highly acidic
water may require additional buffering agents.
Water can also contain
significant numbers of microorganisms. Water used for cleaning and
sanitizing must be potable and pathogen-free. Treatments and
sanitization of water may be required prior to use in cleaning
regimes. Water impurities which effect cleaning functions are
presented in Table 1.
Cleaning
Properties of Food Soils
Food soil is generally defined
as unwanted matter on food-contact surfaces. Soil is visible or
invisible. The primary source of soil is from the food product being
handled. However, minerals from water residue and residues from
cleaning compounds contribute to films left on surfaces.
Microbiological biofilms also contribute to the soil buildup on
surfaces.
Since soils vary widely in
composition, no one detergent is capable of removing all types. Many
complex films contain: combinations of food components, surface oil
or dust, insoluble cleaner components, and insoluble hard-water
salts. These films vary in their solubility properties depending
upon such factors as heat effect, age, dryness, time, etc.
It is essential that personnel
involved have an understanding of the nature of the soil to be
removed before selecting a detergent or cleaning regime. Therule of
thumb is that acid cleaners dissolve alkaline soils (minerals) and
alkaline cleaners dissolve acid soils and food wastes. Improper use
of detergents can actually "set" soils, making them more difficult
to remove (e.g., acid cleaners can precipitate protein). Many films
and biofilms require more sophisticated cleaners which are amended
with oxidizing agents (such as chlorinated detergents) for removal.
Soils may be classified as:
-
soluble in water (sugars,
some starches, most salts);
-
soluble in acid (limestone
and most mineral deposits);
-
soluble in alkali (protein,
fat emulsions);
-
soluble in water, alkali, or
acid.
The physical condition of the
soil deposits also effects its solubility. Freshly precipitated soil
in a cool or cold solution is usually more easily dissolved than an
old, dried, or baked-on deposit, or a complex film.Food soils are
complex in that they contain mixtures of several components. A
general soil classification and removal characteristics is presented
in Table 2
.
Fat-based Soils
Fat usually is present as an
emulsion and can generally be rinsed away with hot water above the
melting point. More difficult fat and oil residues can be removed
with alkaline detergents which have good emulsifying or saponifying
ingredients.
Protein-based Soils
In the food industry, proteins
are by far the most difficult soils to remove. In fact, casein (a
major milk protein) is used for its adhesive properties in many
glues and paints. Food proteins range from more simple proteins,
which are easy to remove, to more complex proteins, which are very
difficult to remove. Heat-denatured proteins can be extremely
difficult.
Generally, a highly alkaline
detergent with peptizing or dissolving properties is required to
remove protein soils. Wetting agents can also be used to increase
the wettability and suspendability of proteins. Protein films
require alkaline cleaners which have hypochlorite in addition to
wetting agents.
Carbohydrate-based Soils
Simple sugars are readily
soluble in warm water and are quite easily removed. Starch residues,
individually, are also easily removed with mild detergents. Starches
associated with proteins or fatscan usually be easily removed by
highly alkaline detergents.
Mineral Salt-based Soils
Mineral salts can be either
relatively easy to remove, or be highly troublesome deposits or
films. Calcium and magnesium are involved in some of the most
difficult mineral films. Under conditions involving heat and
alkaline pH, calcium and magnesium can combine with bicarbonates to
form highly insoluble complexes. Other difficult deposits contain
iron or manganese. Salt films can also cause corrosion of some
surfaces. Difficult salt films require an acid cleaner (especially
organic acids which form complexes with these salts) for removal.
Sequestering agents such as phosphates or chelating agents are often
used in detergents for salt film removal.
Microbiological Films
Under certain conditions,
microorgranisms (bacteria, yeasts, and molds) can form invisible
films (biofilms) on surfaces. Biofilms can be difficult to remove
and usually require cleaners as well as sanitizers with strong
oxidizing properties.
Lubricating Greases and Oils
These deposits (insoluble in
water, alkali, or acid) can often be melted with hot water or steam,
but oftenleave a residue. Surfactants can be used to emulsify the
residue to make it suspendable in water and flushable.
Other Insoluble Soils
Inert soils such as sand,
clay, or fine metal can be removed by surfactant-based detergents.
Charred or carbonized material may require organic solvents.
Quantity of Soil
It is important to rinse food-contact
surfaces prior to cleaning to remove most of the soluble soil. Heavy
deposits require more detergent to remove. Improper cleaning can
actually contribute to build-up of soil.
The Surface Characteristics
The cleanability of the
surface is a primary consideration in evaluating cleaning
effectiveness. Included in surface characteristics are:
-
Surface Composition.
Stainless steel is the preferred surface for food equipment and is
specified in many industry and regulatory design and construction
standards. For example: 3-A
Sanitary Standards (equipment standards used for milk and milk
products applications) specify 300 series stainless steel or
equivalent. Other grades of stainless steel may be appropriate for
specific applications (i.e 400 series) such as handling of high
fat products, meats, etc. For
highly acidic, high salt, or other highly corrosive products, more
corrosion resistant materials (i.e. titanium) is often
recommended.
Other "soft" metals (aluminum,
brass, copper, or mild steel), or nonmetallic surfaces (plastics, or
rubber) are also used on food contact surfaces. Surfaces of soft
metals and nonmetallic materials are generally less corrosion-
resistant and care should be exercised in their cleaning.
Aluminum is readily attacked
by acids as well as highly alkaline cleaners which can render the
surface non-cleanable. Plastics are subject to stress cracking and
clouding from prolonged exposure to corrosive food materials or
cleaning agents.
Hard wood (maple or
equivalent) or sealed wood surfaces should only be used in limited
applications such as cutting boards or cutting tables provided the
surface is maintained in good repair. Avoid using porous wood
surfaces.
-
Surface Finish.
Equipment design and construction standards also specify finish
and smoothness requirements. 3-A standards specify a finish at
least as smooth as a No. 4 ground finish for most application.
With high-fat products, a less smooth surface is used to allow
product release from the surface.
-
Surface Condition.
Misuse or mishandling can result in pitted, cracked, corroded, or
roughened surfaces. Such surfaces are more difficult to clean or
sanitize, and may no longer be cleanable. Thus, care should be
exercised in using corrosive chemicals or corrosive food products.
Environmental Considerations
Detergents can be significant
contributors to the waste discharge(effluent). Of primary concern is
pH. Many publicly owned treatment works limit effluent pH to the
range of 5 to 8.5. So, it is recommended that in applications where
highly alkaline cleaners are used, that the effluent be mixed with
rinse water (or some other method be used) to reduce the pH.
Recycling of caustic soda cleaners is also becoming a common
practice in larger operations. Other concerns are phosphates, which
are not tolerated in some regions of the U.S., and the overall soil
load in the waste stream which contributes to the chemical oxygen
demand (COD) and biological oxygen demand (BOD).
Chemistry of Detergents
Detergents and cleaning
compounds are usually composed of mixtures of ingredients that
interact with soils in several ways:
-
Physically active
ingredients alter physical characteristics such as solubility or
colloidal stability.
-
Chemically active
ingredients modify soil components to make them more soluble and,
thus, easier to remove.
In some detergents, specific
enzymes are added to catalytically react with, and degrade, specific
food soil components.
Physically Active Ingredients
The primary physically active
ingredients are the surface active compounds termed surfactants.
These organic molecules have general structural characteristicwhere
a portion of the structure is hydrophilic (water- loving) and a
portion is hydrophobic (not reactive with water). Such molecules
function in detergents by promoting the physical cleaning actions
through: emulsification, penetration, spreading, foaming, and
wetting.
The classes of surfactants
are:
-
Ionic surfactants
which are negatively charged in water solution are termed
anionic
surfactants. Conversely, positively charged
ionic surfactants are termed
cationic surfactants. If the
charge of the water soluble portion is depended upon the pH of the
solution it is termed an
amphoteric surfactant. These
surfactants behave as cationic
surfactants under acid
conditions, and as anionic
surfactants under alkaline conditions.
Ionic surfactants are generally characterized by their high
foaming ability.
-
Nonionic surfactants
, which do not dissociate when dissolved in water, have the
broadest range of properties depending upon the ratio of
hydrophilic/ hydrophobic balance. This balance is also affected by
temperature. For example, the
foaming properties of nonionic detergents is affected by
temperature of solution. As temperature increases, the hydrophobic
character and solubility decreases. At the cloud point (minimum
solubility), these surfactants generally act as defoamers, while
below the cloud point they are varied in their foaming properties.
It is a common practice to
blend surfactant ingredients to optimize their properties. However,
because of precipitation problems,
cationic and
anionic
surfactants cannot be blended
Chemically Active Ingredients
Alkaline Builders
Highly Alkaline Detergents
(or heavy-duty detergents) use caustic soda (sodium hydroxide)
or caustic potash (potassium hydroxide). An important property of
these highly alkaline detergents is that they saponify fats: forming
soap. These cleaners are used in many CIP systems or bottle-washing
applications.
Moderately Alkaline
Detergents include sodium, potassium, or ammonium salts of
phosphates, silicates, or carbonates. Tri-sodium phosphate (TSP) is
one of the oldest and most effective. Silicates are most oftenused
as a corrosion inhibitor. Because of interaction with calcium and
magnesium and film formation, carbonate-based detergents are of only
limited use in food processing cleaning regimes.
Acid Builders
Acid Detergents include
organic and inorganic acids. The most common inorganic acids used
include: phosphoric, nitric, sulfamic, sodium acid sulfate, and
hydrochloric. Organic acids, such as hydroxyacetic, citric, and
gluconic, are also in use. Acid detergents are often used in a
two-step sequential cleaning regime with alkaline detergents. Acid
detergents are also used for the prevention or removal of stone
films (mineral stone, beer stone, or milk stone).
Water Conditioners
Water conditioners are used to
prevent the build-up of various mineral deposits (water hardness,
etc.). These chemicals are usually sequestering agents or chelating
agents. Sequestering agents form soluble complexes with
calcium and magnesium. Examples are sodium tripolyphosphate,
tetra-potassium pyrophosphate, organo-phosphates, and
polyelectrolytes. Chelating agents include sodium gluconate
and ethylene diamine tetracetic acid (EDTA).
Oxidizing Agents
Oxidizing agents used in
detergent application are hypochlorite (also a sanitizer) and--to a
lesser extent -- perborate. Chlorinated detergents are most often
used to clean protein residues.
Enzyme Ingredients
Enzyme-based detergents, which
are amended with enzymes such as amylases and other carbohydrate-
degrading enzymes, proteases, and lipases, are finding acceptance in
specialized food industry applications.
The primary advantages of
enzyme detergents are that they are more environmentally friendly
and often require less energy input (less hot water in cleaning).
Uses of most enzyme cleaners are usually limited to unheated
surfaces ( e.g.,
cold-milk surfaces). However, new generation
enzyme cleaners (currently under evaluation) are expected to have
broader application.
Fillers
Fillers add bulk or mass, or
dilute dangerous detergent formulations which are difficult to
handle. Strong alkalis are often diluted with fillers for ease and
safety of handling. Water is used in liquid formulations as a
filler. Sodium chloride or sodium sulfate are often fillers in
powdered detergent formuations.
Miscellaneous Ingredients
Additional ingredients added
to detergents may include: corrosion inhibitors, glycol ethers, and
butylcellosolve (improve oil, grease, and carbon removal).
Sanitizing
Thermal Sanitizing
As with any heat treatment,
the effectiveness of thermal sanitizing is dependant upon a number
of factors including: initial contamination load, humidity, pH,
temperature, and time.
Steam
The use of steam as a
sanitizing process has limited application. It is generally
expensive compared to alternatives, and it is difficult to regulate
and monitor contact temperature and time. Further, the byproducts of
steam condensation can complicate cleaning operations.
Hot Water
Hot-water sanitizing--through
immersion (small parts, knives, etc.), spray (dishwashers), or
circulating systems--is commonly used. The time required is
determined by the temperature of the water. Typical regulatory
requirements (Food Code 1995) for use of hot water in dishwashing
and utensil sanitizing applications specify: immersion for at least
30 sec. at 77°C (170°F) for manual operations; a final rinse
temperature of 74°C (165°F) in single tank, single temperature
machines and 82°C (180°F) for other machines.
Many state regulations require
a utensil surface temperature of 71°C (160°F) as measured by an
irreversibly registering temperature indicator in warewashing
machines. Recommendations andrequirements for hot-water sanitizing
in food processing may vary. The Grade A Pasteurized Milk Ordinance
specifies a minimum of 77°C (170°F) for 5 min. Other recommendations
for processing operations are: 85°C (185°F) for 15 min., or 80°C
(176°F) for 20 min.
The primary advantages of
hot-water sanitization are: relatively inexpensive, easy to apply
and readily available, generally effective over a broad range of
microorganisms, relatively non-corrosive, and penetratesinto cracks
and crevices. Hot-water sanitization is a slow process which
requires come-up and cool-down time; can have high energy costs; and
has certain safety concerns for employees. The process also has the
disadvantages of forming or contributing to film formations, and
shortening the life of certain equipment or parts thereof (gaskets,
etc.).
Chemical Sanitizing
The ideal chemical sanitizer
should:
-
be approved for food contact
surface application
-
have a wide range or scope
of activity.
-
destroy microorganisms
rapidly.
-
be stable under all types of
conditions.
-
be tolerant of a broad range
of environmental conditions.
-
be readily solubilized and
possess some detergency.
-
be low in toxicity and
corrosivity.
-
be inexpensive.
No available sanitizer meets
all of the above criteria. Therefore, it is important to evaluate
the properties, advantages, and disadvantages of available sanitizer
for each specific application.
Regulatory Considerations
The regulatory concerns
involved with chemical sanitizers are: antimicrobial activity or
efficacy, safety of residues on food contact surfaces, and
environmental safety. It is important to follow regulations that
apply for each chemical usage situation. The registration of
chemical sanitizers and antimicrobial agents for use on food and
food product contact surfaces, and on nonproduct contact surfaces,
is through the U.S. Environmental Protection Agency (EPA). (Prior to
approval and registration, the EPAreviews efficacy and safety data,
and product labeling information.
The U.S. Food and Drug
Administration (FDA) is primarily involved in evaluating residues
form sanitizer use which may enter the food supply. Thus, any
antimicrobial agent and its maximum usage level for direct use on
food or on food product contact surfaces must be approved by the
FDA. Approved no-rinse food contact sanitizes and nonproduct contact
sanitzers, their formulations and usage levels are listed in the
Code of Federal Regulations
(21 CFR 178.1010). The U.S. Department of
Agriculture (USDA) also maintains lists of antimicrobial compounds
(i.e., USDA List of Proprietary
Substances and Non Food Product Contact Compounds
) which are primarily used in the regulation
of meats, poultry, and related products by USDA's Food Safety and
Inspection Service (FSIS.).
Factors Affecting Sanitizer
Effectiveness
Physical Factors
Surface Characteristics.
Prior to the sanitization process, all surfaces must be clean
and thoroughly rinsed to remove any detergent residue. An unclean
surface cannot be sanitized. Since the effectiveness of sanitization
requires direct contact with the microorganisms, the surface should
be free of cracks, pits, or crevices which can harbor
microorganisms. Surfaces which contain biofilms cannot be
effectively sanitized.
Exposure Time.
Generally, the longer time a sanitizer chemical is in contact with
the equipment surface, the more effective the sanitization effect;
intimate contact is as important as prolonged contact..
Temperature.
Temperature is also positively related to microbial kill by a
chemical sanitizer. Avoid high temperatures (above 55°C [131°F])
because of the corrosive nature of most chemical sanitizers.
Concentration.
Generally, the activity of a sanitizer increases with increased
concentration. However, a leveling off occurs at high
concentrations. A common misconception regarding chemicals is that
"if a little is good, more is better". Using sanitizer
concentrations above recommendations does not sanitizer better and,
in fact, can be corrosive to equipment and in the long run lead to
less cleanability. Follow manufacturer's label instructions.
Soil. The presence of
organic matter dramatically reduces the activity of sanitizers and
may, in fact, totally inactivate them. The adage is "you cannot
sanitize an unclean surface".
Chemical Factors
pH. Sanitizers are
dramatically affected by the pH of the solution. Many chlorine
sanitizers, for example, are almost ineffective at pH values above
7.5.
Water properties.
Certain sanitizers are markedly affected by impurities in the water.
Inactivators. Organic
and/or inorganic inactivators may react chemically with sanitizers
giving rise to non-germicidal products. Some of these inactivators
are present in detergent residue. Thus, it is important that
surfaces be rinsed prior to sanitization.
Biological Factors
The microbiological load can
affect sanitizer activity. Also, the type of microorganism present
is important. Spores are more resistant than vegetative cells.
Certain sanitizers are more active against gram positive than gram
negative microorganisms, and vice versa. Sanitizers also vary in
their effectiveness against yeasts, molds, fungi, and viruses.
Specific Types of Chemical
Sanitizers
The chemicals described here
are those approved by FDA for use as no-rinse, food-contact surface
sanitizers. In food-handling operations, these are used as rinses,
sprayed onto surfaces, or circulated through equipment in CIP
operations. In certain applications the chemicals are foamed on a
surface or fogged into the air to reduce airborne contamination.