cleaning of dairy equipment

8/4/2019 Cleaning of Dairy Equipment

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Cleaningof dairy

equipment

Department of Veterinary Public Health



Introduction

The safety and wholesomeness of dairyproducts is highly dependent upon theeffective control of unwanted micro-organisms

in the plant.A critical step in the production of a safe andwholesome product is the effective cleaning

and sanitation of equipment and thesurrounding environment.



CleaningCLEANING is the removal of dirt, dust, food particles,and debris from a surface by washing with a cleaningsolution.

The following terms are used to define the degree ofcleanliness:

Physical cleanliness – removal of all visible dirt from thesurface;

Chemical cleanliness – removal not only of all visible dirt butalso of microscopic residues which can be detected by taste

or smell but are not visible to the naked eye;

Bacteriological cleanliness – attained by disinfection;

Sterile cleanliness – destruction of all micro-organisms.



Cleaning procedures

Manual

cleaning

Automaticcleaning



A. Manual cleaning

Cleaning of dairy equipment wasformerly done (and still is in someplaces) by people armed with

brushes and detergent solutions,who had to dismantle equipmentand enter tanks to get at thesurfaces.This was not only laborious butalso ineffective; products wereoften re-infected from imperfectly

cleaned equipment.



B. Automatic cleaning

Circulatory cleaning-in-place (CIP)systems adapted to

the various parts ofa processing planthave beendeveloped to

achieve goodcleaning andsanitation results.



The cleaning cycle in a dairy comprises thefollowing stages

Recovery of productresidues by scraping,

drainage andexpulsion with wateror compressed air;

Pre-rinsingwith water toremove loose

dirt;

Cleaning

withdetergent

Rinsing withclean water;

Disinfection by heating or withchemical agents step is included,the cycle ends with a final rinse, if

the water quality is good.



Recovery of product residues

All product residues should be recovered fromthe production line at the end of the run.

This is important for three reasons:• To minimize product losses, • To facilitate cleaning, • To reduce the load on the sewage system

Before cleaning starts, the remaining milk isforced out of the production lines with water.



Pre-rinsing with water Pre-rinsing should always be carried outimmediately after the production run.Otherwise the milk residues will dry and stick

to the surfaces, making them harder to clean.Milk fat residues are more easily flushed out ifthe prerinsing water is warm, but thetemperature should not exceed 55°C to avoid

coagulation of proteins.Normally 99% of the total residues, can beremoved by efficient pre-rinsing.



Cleaning with detergent The dirt on heated surfaces is normally washedoff with alkaline and acid detergents, in that orderor the reverse order, with intermediate water

flushing, whereas cold surfaces are normallycleaned with alkalis and only occasionally with anacid solution.To obtain good contact between the alkaline

detergent solution and the film of dirt, it is necessary to add a surfactant which lowers the surface tension of the liquid.Teepol (alkyl aryl sulphonate), an anionicsurfactant, is usually used.



Rinsing with clean water After cleaning with detergent the surfaces must beflushed with water long enough to remove alltraces of the detergent.Any detergent left in the system after cleaning cancontaminate the milk.All parts of the system must be thoroughly drainedafter rinsing.Softened water is preferred for rinsing. This

prevents deposition of lime scale on the cleanedsurfaces.Hard water with a high content of calcium saltsmust therefore be softened first and then it is use.



Disinfection Properly carried out cleaning with acid andalkaline detergents renders the equipment notonly physically and chemically but also, to a large

extent, bacteriologically clean.The bacteriological cleaning effect can be furtherimproved by disinfection.This leaves the equipment virtually free frombacteria.For certain products (UHT milk, sterile milk) it isnecessary to sterilize the equipment to render thesurfaces completely free from bacteria.



Dairy equipment can be disinfected in thefollowing ways

• Boiling water, Hot water, Steam.

Thermal disinfection

• Chlorine, Acids, Iodophors, Hydrogenperoxide etc.

Chemical disinfection



Factors affecting cleaning

Solution temperature

Duration of application

Mechanical action

Chemical concentration

Water hardness

Other water impurities



Cleaning-in-place systems

Cleaning-in-place means that rinsing water and detergentsolutions are circulated through tanks, pipes and process lineswithout the equipment having to be dismantled.CIP can be defined as circulation of cleaning liquids throughmachines and other equipment in a cleaning circuit.The passage of the high-velocity flow of liquids over theequipment surfaces generates a mechanical scouring effectwhich dislodges dirt deposits.This only applies to the flow in pipes, heat exchangers, pumps,valves, separators, etc.

The normal technique for cleaning large tanks is to spray thedetergent on the upper surfaces and then allow it to run downthe walls.The mechanical scouring effect is then often insufficient, but the

effect can to some extent be improved by the use of speciallydesigned spray devices.



CIP programs

Dairy CIP programs differ according to whether thecircuit to be cleaned contains heated surfaces ornot.We distinguish between:

• CIP programs for circuits with pasteurizers andother equipment with heated surfaces (UHT, etc.).

• CIP programs for circuits with pipe systems, tanks

and other process equipment with no heatedsurfaces;The main difference between the two types is thatacid circulation must always be included in the firsttype to remove encrusted protein and salts fromthe surfaces of heat-treatment equipment.

A CIP f i "h



A CIP program for a pasteuriser, "hot components", circuit can consist of the following stages :

Gradual cooling with cold water for about 8 minutes.

Post-rinsing with cold water.

Circulation of (nitric) acid solution (0.5 – 1.0 %) for about 20 minutes at 70°C.

Rinsing out alkaline detergent with warm water for about 5 minutes.

Circulation of an alkaline detergent solution (0.5 – 1.5%) for about 30 minutes at 75°C.

Rinsing with warm water for about 10 minutes.

f h k



A CIP program for a circuit with pipes, tanksand other “cold components“ can comprise thefollowing stages:

Gradual cooling with cold tap water for about 10 minutes (normally no cooling for tanks).

Disinfection with hot water 90 – 95°C for 5 minutes.

Rinsing with warm water for about 3 minutes.

Circulation of a 0.5 – 1.5% alkaline detergent at 75°C for about10 minutes.

Rinsing with warm water for 3 minutes.

cleaning of dairy equipment

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