Every company should set up good housekeeping, cleaning, and sanitization programs for its entire plant environment that meet the specific needs in each area. Good manufacturing practices depend on the cleaning and sani-tization practices used and their frequencies of performance within the plant.
The specific procedures and schedules for the cleaning and sanitization of equipment and the physical plant should be written.
Several factors determine the effectiveness of cleaning and sanitization.
Three of these factors are (1) the use of well-designed equipment, (2) the use of good cleaning and sanitizing products, and (3) the use of validated pro-cesses. Finally, management must provide training and supervision of employees. A company must include timely cleaning and sanitization sched-ules in its quality assurance program. When it does, it will benefit from the insignificant levels of microorganisms present in its manufacturing equip-ment and plant facilities.
Cleaning
Cleaning is the physical removal of product or ingredient residues. Cleaning removes grease, dust, and contaminants from the surfaces of manufacturing equipment and the environmental surfaces of buildings. Physical removal requires the application of energy in some form such as scrubbing, spraying, or turbulent flow. Most cosmetic manufacturers use cleaning agents to aid physical removal of such materials. These agents break down soil in order to allow both visible and invisible foreign matter to rinse away. An ideal cleaning agent should be readily soluble and should provide good penetra-tion and emulsifying acpenetra-tion. It should be compatible with equipment, non-corrosive, and possess good wetting and rinsing properties.
Detergent formulations are ideal to use for most cleaning activities.
Technically, a detergent is any cleaning agent. However, in popular usage, detergents are washing and cleaning agents with compositions other than metal salts of acids derived from fat (soaps). They react basically by the same mechanisms as soaps. All detergents possess the basic properties of pene-tration, wetting, dispersion, and emulsifying action.
Detergents may contain surfactants, builders, agents for penetrating, wetting, deflocculating, foaming, emulsifying, sequestering or chelating, and soil dispersants. The surfactants may be ampholytic, anionic, cationic, or nonionic. The choice of a detergent should be based on its intended use and the type of soil to be removed.
Detergent ingredients and properties
In describing detergents and their properties, a vocabulary unique to the industry has evolved. For that reason, we include definitions or explanations for a variety of common terms.
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76 Cosmetic Microbiology: A Practical Approach Detergency is defined as the ability to clean soil or other unwanted material from a surface. A detergent accomplishes this task through a com-bination of processes including the lowering of surface and interfacial ten-sion, solubilizing or emulsifying, inactivating water hardness, and neutral-izing acid soil.
Builders are materials that upgrade or protect the detergency of a sur-factant. Builders perform several functions including inactivation of water hardness, increasing alkalinity to aid cleaning, providing a buffer, suspend-ing soil, and emulsifysuspend-ing oily or greasy soils. Some builders help deflocculate or break up solid masses into smaller particles and disperse them through a liquid medium.
Dispersing agents are chemicals that increase the stability of particles in a liquid. These agents help remove soil particles by keeping them in a dispersed or suspended state during equipment rinsing. The mechanism of dispersal may be the process of emulsification involving dispersal or sus-pension of fine particles or globules of one or more liquids in another liquid.
Similar terms for dispersing agents are soil suspending agents or inhibitors of soil redeposition. Dispersing agents are ingredients of detergents intended to keep soil suspended and dispersed in the cleaning solution. They reduce redeposition of the soil on surfaces by detaching soil globules from a surface and dispersing them through the cleaning solution. Surfactants are the prin-cipal emulsifying agents.
Foaming agents are chemical agents that increase the foaming or sudsing characteristics of a cleaning agent. Penetration refers to the characteristic that permits the cleaning solution (water) to get under the soil and loosen it from a surface. It also helps the solution to work its way through the soil.
Chelating agents are organic sequestering agents that inactivate water hardness and other metallic ions in water. A commonly used chelating agent is EDTA (ethylene diamine tetraacetic acid and its salts). A sequestrant is a chelating compound in an aqueous solution that combines with a metallic ion to form a water-soluble combination. The ion in the combination is inactive. Sequestrants soften water without the precipitation associated with other methods like lime softening. For example, complex phosphates are sequestrants that inactivate divalent metal ions such as calcium, magnesium, iron, and manganese without precipitation.
Surfactants (surface active agents) are organic chemicals that are added to liquids to change the surface-active properties of the liquids. Surfactants and soaps perform the important function of lowering the surface tension of water. Surfactants help remove fatty and particulate soils. They also keep soils emulsified, suspended, and dispersed to prevent settling at the surface.
Surfactants are also wetting agents. They increase the ability and speed with which liquid displaces air from a solid surface. This property improves the process of wetting surfaces. Surfactants lower the surface and interfacial tensions. This enables a cleaning solution to more quickly wet a surface. The chemical action of a surfactant can be enhanced by employing mechanical action to more readily remove soils.
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chapter three: Microbial environment of the manufacturing plant 77
Types of surfactants
Amphoteric (ampholytic) surfactants may be either anionic or cationic, depending on pH. They are useful because of their wide compatibility with builders, acids, and alkalis. The properties of an anionic surfactant depend in part on the negatively charged ion (anion) of the molecule. This property accounts for the anionic designation. The detergent industry uses a wide range of anionic surfactants that are highly sudsing. Excess foaming is unde-sirable for surface cleaning. It leaves a residue from excess foam. This residue produces a tacky surface that presents a likely resoiling problem.
A cationic surfactant has a positively charged ionic group. Quaternary ammonium compounds are the most widely used cationic surfactants. They are used as sanitizers and disinfectants, fabric softeners, and static electricity dissipaters. They are not typically used alone as cleaning agents.
Nonionic surfactants do not contain positively or negatively charged functional groups. They are particularly effective for removing oily soil and many are low sudsing. They do not ionize in water as do anionic and cationic surfactants.
The surfactant industry also has a unique vocabulary for cleaning. We will describe these terms as well. A general purpose cleaner contains sodium hydroxide or sodium carbonate for alkalinity along with a sequestering agent. Some cleaners also include low-foaming wetting agents and silicates to inhibit corrosion. These cleaners are different from clean-in-place (CIP) cleaners that have the same formula as general purpose cleaners but contain nonfoaming wetting agents. A manual washing cleaner will exhibit lower alkalinity and contain a high-foaming agent. An acid cleaner contains an organic or mineral acid to remove hard water and mineral deposits. It may also include a heterocyclic nitrogen compound to inhibit corrosion and a wetting agent to allow penetration. Alkaline cleaners are of the general purpose type but they contain very high levels of sodium hydroxide or sodium carbonate. They are ideal for very difficult cleaning jobs.
Personnel should limit the use of cleaning agents in a plant to those necessary for accomplishing the assigned tasks. No single all-purpose cleaner serves every cleaning need, but use of duplicate products should be avoided wherever possible.
Sanitization
Sanitization is the adequate treatment of surfaces by a process that is effective in destroying vegetative cells of pathogenic bacteria. It also should reduce spoilage microorganisms to insignificant levels. Chemical residuals from such treatment should not adversely affect products and should be safe for consumers.
Use of a sanitizer should be preceded by a cleaning procedure. An alternative is to use a combination disinfectant–detergent or detergent–san-itizer in a single-step procedure — a practice usually reserved for
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78 Cosmetic Microbiology: A Practical Approach mental surfaces. Typically, combinations exhibit compromised detergent or disinfectant activity and are not as effective as using both agents separately.
Sanitizers are EPA-registered chemicals that reduce viable microbial con-taminants on surfaces to safe levels. The definition of safe levels is dependent on public health or product requirements. The choice of a sanitizer should consider the characteristics, efficacy, and applicable regulations. An ideal sanitizer should:
• Kill microorganisms rapidly (within 30 to 60 seconds)
• Provide adequate microbial reduction (about 99.9%, a 3 log reduc-tion)
• Be effective against a broad spectrum of microorganisms
• Be safe and nontoxic to employees handling it
• Be safe for consumers at use levels
• Be acceptable to regulatory agencies
• Exert no adverse effects on the product
• Be economical to use
• Be rinsable
• Leave no objectionable odor or residue
• Be stable in its concentrated form and at use levels
• Be noncorrosive
• Exhibit compatibility with equipment and other chemicals
• Possess ready solubility in water
• Be biodegradable at concentrations expected in a waste receiving stream
Furthermore, tests to detect a sanitizer in solution should be easy to conduct.
Chemical sanitizers
Several chemical sanitizers are appropriate for various sanitization proce-dures within a manufacturing facility. A variety of reference books and product bulletins will provide detailed information about the numerous chemical sanitizers and specific product formulations. As a rule, experience with a sanitizer is usually the only reliable benchmark for its usefulness.
Chlorine is usually provided as a component sodium or calcium hypochlorite. Dichloro- or trichloro-isocyanuric acid and its salts are also chlorine-releasing sanitizers. Chlorine mixed with ammonia forms chloram-ine — which provides a good residual chlorchloram-ine source for disinfecting water.
Chlorine is useful for disinfecting water, process systems, and environmental surfaces.
An iodophor is an iodine-releasing formulation contained in a carrier.
Depending on the intended use of the product, the carrier may or may not contain a nonionic detergent. Iodine is useful for surface and skin disinfec-tion. In some cases, it is useful for water disinfection but this effect of chlorine use is secondary.
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chapter three: Microbial environment of the manufacturing plant 79 Quaternary ammonium compounds consist of cationic surfactants. The most frequent use for this type of chemical sanitizer is in combination with a nonionic detergent as a disinfectant–detergent or detergent–sanitizer. How-ever, nonionic detergents usually do not clean as well as more caustic cationic detergents. Typically, one can achieve more effective cleaning and sanitizing by separating the cleaning and sanitizing steps rather than combining them.
This is because most cleaners operate best at high pH levels and most disinfectants operate best at acidic to neutral pH.
Ethyl alcohol has limited use as a chemical sanitizer because of flamma-bility risks. However, it can be diluted to 50 to 70% final concentration with water partially to mitigate this concern while providing good antimicrobial activity. It is effective at cutting the films of surfactant-containing products while providing some sanitizing impact. Ethyl alcohol does not kill spores.
It is useful as a hand antiseptic for short periods. Many antiseptic products are now available that provide alcohol in an emollient form to reduce drying and chapping of the hands. Ethyl alcohol is more pleasant to use than isopropyl, which encourages plant personnel to use it for cleaning spills and tank tops.
While phenolics have value as sanitizers when used alone, they are more frequently combined with anionic detergents to produce disinfectant–deter-gents. Formalin is also useful. However, it should always be used in a closed system that does not permit it to escape into the air. Tighter restrictions on formalin use are likely because of OSHA regulations. Formaldehyde is a suspected carcinogen.
Phosphoric acid has only limited use in a plant environment. It is com-bined with other chemical products such as iodophors and used in tile and bathroom cleaners. Hydrogen peroxide is not used extensively as a chemical sanitizer. It is primarily useful for cleaning deep puncture wounds of the skin. Its bubbling action helps to lift out dirt deep within a wound but its disinfection capacity is minimal. Pine oil also has limited use in a manufac-turing plant.
Peracetic acid is a combination of peracetic acid, acetic acid, hydrogen peroxide, and water that works as a very strong oxidizer. It is a broad spectrum disinfectant that has demonstrated good level of activity against biofilms. Peracetic acid has a pungent odor and is very irritating to the eyes and nose. It is noncorrosive to stainless steel.
Physical sanitizers
Heat is the most efficient and thorough physical sanitizer. In our plant, we provide it as steam (100°C/212°F) or hot water (80 to 100°C/176 to 212°F).
If the steam is under pressure, the temperature can be even higher (121 to 132°C/250 to 270°F). In cosmetic manufacturing, we usually do not use dry heat. Table 3.1 defines the temperatures required for sanitizing via dry heat and steam heat. Note that these exposure times and temperatures are not effective for sterilization.
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80 Cosmetic Microbiology: A Practical Approach
Heat has several advantages over other sanitizing agents — chemical and physical. These advantages include (1) ability to penetrate into small cracks and crevices, (2) noncorrosive action, (3) nonselective treatment of microbial groups, (4) absence of residues on surfaces, (5) ability to be easily measured, and (6) reasonable cost.
The use of steam or hot water poses some challenges. Heat may cause condensation problems because of the high humidity created. Only thermo-stable materials can withstand the heat generated by steam or hot water.
High energy costs are usually offset by reduced labor costs when compared to the costs of chemical sanitizers. When heat treatment is not cost effective, we must consider the proficiency of heat treatment compared with chemical sanitization treatments.
Ultraviolet (UV) light is of very limited use as a sanitizer in cosmetic microbiology practice. It can damage the eyes of personnel in the area if used as a local sanitizer. It has poor penetrating power and so must be used near the material to be treated. The UV intensity decreases by the square of the distance from the source. The typical use is for water sanitization, nor-mally in combination with ozonated water systems. One use of UV lights is as point source polishers to remove the ozone. They also kill microorganisms that may have survived the ozonation process. UV is ineffective as an air sanitizer in large, open areas.
One example of the use of combined chemical and physical sanitization is the application of a cleaner or sanitizer with steam or hot water. This approach will usually increase the effectiveness of the chemical agent. How-ever, the chemical agent must be compatible with the heat application. For example, heat does not significantly enhance hypochlorite activity except to improve the wetting characteristics of the water. When using chlorine gas as the chlorinating agent, heat may actually drive out the chlorine. This occurs when the chlorine is not converted to hypochlorous acid, especially at low pH. This reduces the effectiveness of the chlorine sanitizer and also presents a major safety hazard.
Proper use of chemical agents
Chemical cleaners and sanitizers should be used only according to label directions. All appropriate employees should be thoroughly trained in the proper use of chemical agents. Improper use of an agent will both reduce
Table 3.1 Comparison of Exposure Times and Temperatures for Wet and Dry Heat Sanitization
Exposure Time Wet Heat Dry Heat
1/2 hour 180°F/82°C 355°F/179°C 2 hours 160°F/71°C 320°F/160°C 4 hours 140°F/60°C 285°F/141°C 24 hours 120°F/49°C 250°F/121°C
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chapter three: Microbial environment of the manufacturing plant 81 the effectiveness of the product and produce unsatisfactory or less-than-opti-mal results. Overuse of a product will increase toxicity, increase corrosive-ness, and may adversely affect equipment or product. In addition, federal law prohibits use of an EPA-registered product in any manner inconsistent with its label instructions. Therefore, misuse of an EPA-registered sanitizer is an illegal act.