Chemistry Of Cleaning & Sanitizing

Science starts with definitions.

Cleaning is the complete removal of soils from surfaces. Cleaning processes are unnatural because all surfaces are constantly being soiled. In order to get a clean surface, it is necessary to work against nature.

The clean surface is defined as being free from soil, free from bad odours, be non-greasy to the touch and have no visible oxidation.

Good cleaners must be

Economical Nontoxic Noncorrosive Noncaking Nondusting Easy to measure Stable during storage Easily and completely dissolved.

Major considerations in cleaning compound selection are

The nature of the soil to be cleaned Water characteristics Application method Area and kind of equipment to be cleaned

Soil Identification

Soil1 is the state of being covered with unclean things.

Category Tree:

state ╚condition; status ╚sanitary condition ╚dirtiness; uncleanness ╚ soil, dirt, filth, grime, stain, grease

Soil2 is foreign matter that happens to be in the wrong place. For example, yogurt is food, but if it's poured on carpet, it is considered soil.

Soil3 is any unwanted matter on the surface of an object that one desires to be clean.

Deposit is the phenomenon of sediment or gravel accumulating.

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Category Tree:

phenomenon ╚natural phenomenon ╚geological phenomenon ╚deposit, sedimentation, alluviation

Generally soil and deposit are the same terms define any organic, inorganic or mixture of organic and inorganic compounds on a given surface.

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. The rule 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 for removal.

The physical condition of the soil 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.

Cleaning Methods

1. Clean-in-Place (C.I.P.)

Some parts of the processing machinery such as pipework, heat exchangers , tanks, fillers etc. must be cleaned immediately after the production cycle has finished so that when the next production cycle starts, the system should be cleaned.

C.I.P. signifies Cleaning In Place which means that the removal of soil from product contact surfaces in their process position by circulating, spraying, or flowing chemical solutions and water rinses onto and over the surfaces to be cleaned and the production equipment is cleaned without being dismantled. It is a totally automatic cleaning sequence with no manual involvement.

CIP relies on the principal of applying a suitable detergent or solvent at a suitable flow, pressure, temperature and concentration for the correct length of time. The science is based on applying the required amount of energy to the equipment to ensure that it is cleaned. The energy is primarily provided by the solution temperature (thermal energy), the use of detergent or solvent (chemical energy) and the application of suitable pipeline velocities or pressures (kinetic energy).

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2. Clean-Out-of-Place (COP) 

COP or in its full form, Cleaning Out of Place, is defined as a method of cleaning equipment items by removing disassembled items from their operational area and taking them to the cleaning station for cleaning.

3. Manual Cleaning 

Removal of soil when the equipment is totally disassembled. Soil removal is effected with chemical solutions and water rinses with the assistance of one or a combination of brushes, nonmetallic scouring pads and scrapers, and high or low pressure hoses, with cleaning aids manipulated by hand. 

Sanitization

When the surfaces are cleaned, visible soils are removed. But invisible soils such as bacteria, yeast, mold, etc. can continue to living.

Sanitization is killing of microorganisms which are living on food contact or non-product contact surfaces.

Cleaned surfaces can be sanitized. For example before the using of hand sanitizer, you should wash your hand. Firstly soils on hands remove and then germs are killed. Because soils can be nutrients for germs and they can hide under soils.

Sanitization includes 3 levels.

1. Sanitization 2. Disinfection3. Sterilization

1.Sanitization

Sanitize refers to the reduction of microorganisms levels considered safe from a public health viewpoint. When we sanitize surface, we do not kill all vegetative bacteria or spores we only reduce vegetative microorganism amounts under safe level.

2. Disinfection

Disinfect refers to killing of all vegetative microorganisms. ( not spores )

3.Sterilization

Sterilize refers to killing of all living organisms.

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.

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The official definition (AOAC) 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 .

Water Chemistry and Quality

Water is the cleaning medium most frequently used for soil removal. Water comprises approximately 95-99% of cleaning and sanitizing solutions. Other cleaning media may include air for removal of packaging 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 products.

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 establishments do not normally have an ideal water supply, cleaning compounds must be tailored to the individual water supply and type of operation.

The major functions of water as a cleaning medium include:

1. prerinse for the removal of large soil particles2. wetting (or softening) of soils on the surface where removal is essential3. transport of a detergent to the area to be cleaned4. suspension of soil to be removed5. transport of suspended soil from the surface being cleaned6. rinsing of the cleaning compound from the area being cleaned7. transport of a sanitizer to the cleaned area

The impurities in water can drastically alter the effectiveness of a detergent or a sanitizer. The water should be, free of microorganisms, clear, colorless, noncorrosive, and free of minerals (known as soft water). Hard water, which contains minerals, may interfere with the action of some cleaning compounds, thereby limiting their ability to perform effectively (although some cleaning compounds can counteract the adverse effects of hard water). The hardness of water affects cleaning compound consumption and may cause the formation of films, scale, or precipitates on equipment surfaces.

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