CLEANING AND DISINFECTION Dip. Environmental Health (HS 113) Nadiatul Syima Bt. Mohd Shahid 1.

CLEANING AND DISINFECTION

Dip. Environmental Health (HS 113)Nadiatul Syima Bt. Mohd Shahid

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LEARNING OBJECTIVES

• Define terminologies related to cleaning.• Importance of cleaning.• Describe the hazards from cleaning. • State the cleaning technology.

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WHY DO WE CLEAN?

• To remove bacteria, yeasts and moulds to an acceptable level.

• To create a safe pleasant working environment and reduce the risk of accidents.

• To give customers a good image and avoid bad publicity.

• To reduce the risk of pest infestation.• To reduce the risk of physical contamination.• It is a Legal requirement.

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WHAT IS CLEANING?

Definition :“the act of making things clean”

Or

“removal of residues”

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HAZARDS AND PROBLEMS FROM CLEANING

• Cleaning is intended to eliminate hazards or reduce them to a safe level, negligent or ineffective cleaning can result in many serious hazards and other problems.

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CLEANING TERMS• Abrasives – include hard abrasives, i.e pumice and fine

sand.• Amphoteric surfactants – the active ions of amphoterics can

be either positively or negatively charged, depending on the pH (acidity or alkalinity) of the solution.

• Anionic surfactants – separate in solutions to form ions. The active ion is negatively charged. Most commonly used surfactants and are often mixed with non-ionic surfactants to form basic commercial detergents such as washing up liquid, biodegradable and non-toxic.

• Biodegradability – refers to the property of a surfactant, which allows it to be broken up by bacteria in sewage works, so reducing pollution and toxic hazard to fish. 6

• Cationic surfactants – ionize in solution, the active ion being positively charged. Mixed with non-ionics, they are very commonly used as disinfectants or sanitizers.

• Compatibility – Detergents with different ionic charges should not be mixed as they are not compatible and become inactivated.

• Emulsion – is a suspension of one liquid in another. Detergents have the ability to surround microdroplets of oil or fat and hold them in suspension as an “oil in water” emulsion that can be easily rinsed away.

• Foaming activity – is not an essential part of a detergent and can interfere with mechanical cleaning. In manual cleaning, enables more dirt to be suspended.

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• Non-ionic surfactants – do not ionize in solution ( do not carry a charge). Compatible with anionic, cationic and amphoteric surfactants (blends to improve overall cleaning performance. Generally biodegradable, non-toxic, have good wetting properties and maybe high or low foaming.

• Saponification – is the process of making soap, usually by boiling vegetable and minerals fats and oils with an alkaline material such as caustic soda. Soap is anionic in character and forms a scum in hard water when it reacts with the calcium and magnesium ions.

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• Scouring powder – cleaning powders combining abrasive and often minute amounts of bleaching agent. Can damage enamel or stainless steel surface and should not be used for cleaning these materials.

• Sequestrants – chemicals that counteract the effect of water hardness salts, preventing the formation of scum, which would interfere with the cleaning action of chemicals.

• Solvents – chemicals that have the effect of dissolving specific types of soil. Solvents such as glycol ether, often used in small amounts as a part of a detergent formulation to improve its performance for dealing with oils and fats.

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• Synergism – enhance performance achieved by the mixture of two or more chemicals, the sum of the activity being greater than the total effect of the components acting separately.

• Water hardness – water containing dissolved calcium and magnesium salts. Temporary hardness results from the presence of bicarbonates and these form a scale when water is heated. Hardness interferes with the action of soap causing scum.

• Detergent – • Sanitizer – A chemical agent used for cleansing and

disinfecting surfaces and equipment. (detergent + disinfectant)

• Soil -

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TECHNOLOGY OF CLEANING

• ENERGY IN CLEANING

KINETIC ENERGY Physical - manual labourMechanical –machines Turbulence – liquids (clean in place)

THERMAL ENERGY

Hot water

CHEMICAL ENERGY

Detergents

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TYPES OF CLEANING• CHEMICAL CLEANINGTo improve the efficiency of water as a cleaning chemical and

to counteract the effect of the impurities in water (hardness salts), other chemicals, i.e detergents are added.- Detergents = are chemicals or mixtures of chemicals, made of soap or synthetic substitutes, with or without additives, which are used to remove grease or soiling.

Main Characteristics:-• Surfactancy – the property of a detergent that enables it

to increase the “wetting power” of water by reducing the surface tension. This increases the contact between the soil and the detergent solution, which is able to penetrate the minute irregularities of the dirt more effectively.

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Factors affecting detergents :-• Dispersion – the ability of a detergent to break up

large accumulations of matter into smaller particles. • Suspension – When dirt is broken up into particles,

they become coated with a thin film of detergent, which keeps the particles apart and buoyant. i.e in suspension, allowing them to be rinsed away. This characteristic is commonly referred to as the emulsifying action of detergents.

(Diagram: )

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CLASSIFICATION OF DETERGENTS• Alkaline detergents

- caustic soda (sodium hydroxide). - corrosive to skin

• Acid detergents- to remove mineral, protein and vegetable deposits and contain phosphoric acid.- never be allowed to come into contact with chlorinated compounds because of the consequential release of toxic chlorine gas.

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• Neutral detergents - generally blends of surfactants used for manual dishwashing and manual cleaning.

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DETERGENT ACTIONS

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Types of soil

Two types of soil : organic and inorganic.

• Organic soils- derived from living matter, vegetable oils, starch, sugars and proteins from milk, egg, meat or blood.

• Inorganic soils- waterscale (hardness), oxidized metals (rust), uric acid salts, beerstone etc.

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DISINFECTION• The destruction of microorganisms, but not usually

bacterial spores. However, it reduces them to a safe level.

• Can achieved by using heat, chemicals, irradiation and UV.

• Sterilization – the process of destroying all microorganisms and their spores.

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TYPES OF DISINFECTION1. Heat disinfection – application of heat is the most

reliable and effective in destroying microorganisms. But is not practicable for surfaces. It is used in machines such as dishwashing machines.

2. Steam disinfection – lances producing steam jets maybe used in large food factories to disinfect machinery or surfaces that are difficult to reach.

3. Chemical disinfection – disinfectants suitable for use in the food industry are limited to those that, when used correctly, so will not have a deleterious effect on food.

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Types of chemical disinfectants

• Chlorine • Quaternary ammonium compounds• Amphoteric disinfectants• Biguanides• Iodophors• Peroxy compounds• Alcohols• Aldehydes

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Where to disinfect?• Not all process applicable to all surfaces.• Should only be used on those surfaces where the

presence of microorganisms, at the levels found, will have an adverse effect on the safety or quality of the food handled.

• But restricted to: food-contact surfaces, cleaning materials and equipment, the surface of fruit and vegetables to be consumed raw, and hand disinfection (only when essential).

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TYPES OF CLEANING METHODS 1. Manual clean –hand cleaning2. Dry clean – wiping, scraping, brushing and vacuuming

of dry debris.3. Dishwashing - dishwasher4. Soak clean – for small items (contact with detergents)5. Foam or gel cleaning – increase contact time between

soil and detergent.6. Automated washing machines – i.e trays, racks, bins

and utensils can be automatically washed using purpose built washing machines.

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7. Washdown system – designed to facilitate cleaning by the use of water hoses. This system is used to provide energy for soil removal, to rinse away soil and detergent residue.

8. Clean-in-place (CIP) - replaced hand cleaning in dairies, breweries and potable liquid installation. - it involves circulating non-forming detergents and disinfectants through process equipment in the assembled state. The combines effects of solution turbulence, chemical energy and heat remove soil debris and microorganisms from pipework and ancillary plant, without time consuming dismantling and manual cleaning.

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Basic CIP sequence

1. Pre-rinse with cold water to remove gross soil2. Detergent circulation to remove residual

adhering debris and scale.3. Intermediate rinse with cold water to remove

all traces of detergent.4. Disinfectant circulation to destroy remaining

microorganisms.5. Final rinse with cold water to remove all

traces of disinfectant.

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Choice of disinfect depends on:• Amount of soiling• Type of cleaning equipment• Water hardness• Contact time available• Microorganisms to be destroyed• Type of surface (smoothness/imperviousness)• Stability• Likelihood of taint • Temperature of application• Toxicity – effect on personnel (safety)• Ionic nature of detergent used before disinfection• Method of application

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CLEANING PROCEDURESWhatever the location, industry, soiling type or circumstances, cleaning and disinfection comprises six basic stages:1.Pre-clean: sweeping, wiping or scraping off loose debris, pre-rinsing and/or pre-soaking.2.Main clean: applying detergent and loosening of the main body of dirt.3.Intermediate rinse: removal of loosened dirt and detergent residues.4.Disinfection: destruction of remaining microorganisms.

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5. Final rinse: removal of disinfectant residues (if required).

6. Drying: removal of final rinse water and storing to prevent contamination.

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MANAGEMENT OF CLEANINGCleaning schedules – must be clearly and concisely written, the entire premises should be covered and all equipment/surfaces included.

Schedules should specify:- • surface • person• chemical• equipment used for cleaning• safety of cleaning

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