GREATER MANCHESTER FOOD LIAISON GROUP
LANCASHIRE FOOD OFFICER GROUP
AND
WEST YORKSHIRE PRINCIPAL FOOD OFFICER GROUP
Guidance Notes
for
On-Farm
Pasteurisers
Produced by
Sandra Bailey
Rebecca Ingham
Jim Livesey
Garry Pearson
Allan Watson
Environmental Health Officer
Environmental Health Officer
Public Protection Manager
Senior Environmental Health Officer
Food Safety Manager
Oldham MBC.
Bradford MDC
Hyndburn BC.
Kirklees MC
Rochdale MBC.
Contents
Page
3
Introduction
4
Registration and Approval of premises
1
Commissioning of Pasteurisers
1.1
1.2
1.3
1.4
1.5
1.6
2
2.4
2.5
2.6
2.7
2.8
11
11
11
12
12
12
12
12
12
12
13
13
13
14
14
Pre-use Disinfection
Cleaning
Churns
15
15
15
Cream Separator Pre-use Disinfection and Operation
4.1
4.2
5
General Information
Cleaning, Inspection and Disinfection of Filters
Pre-use Disinfection and Start-up Procedure for Pasteuriser
2.3.1 Hot Start Up
2.3.2 Cold Start Up
2.3.3 Cleaning of Flow Diversion Valve Unit
2.3.4 Flow Diversion Valve Test
Other Start-up Checks
2.4.1 Fitting/ Setting of Flow Restrictor
2.4.2 Visual Inspection of Pasteuriser
2.4.3 Flow Rate Test
Operation of the Pasteuriser
Pasteuriser Cleaning
Cleaning Records
Acid De-scale
Pasteurised Bulk Milk Tanks and Churns
3.1
3.2
3.3
4
5
5
5
5
5
7
7
7
8
8
9
9
9
9
10
10
10
Cleaning and Operating Procedures
2.1
2.2
2.3
3
Introduction
Documentation
Training
Pre-production Testing
1.4.1 Flow Rate
1.4.2 Holding Time Test
1.4.3 Calibration of Thermometers and Temperature Recorders
1.4.4 Operating Temperature of the Pasteuriser
1.4.5 Positioning of the Flow Diversion Valve
1.4.6 Flow Diversion Valve Check
1.4.7 Heat Exchanger Integrity
1.4.8 Volume of Liquid in the Plant
1.4.9 Pressure Checks
1.4.10 Ancillary Equipment
1.4.11 End Product Testing on Completion of Commissioning
Routine Maintenance and Calibration of the Pasteuriser
Routine Maintenance of Other Dairy Machine
Disinfection of the Cream Separator
Cleaning of the Cream Separator
16
16
Homogeniser Pre-use Disinfection and Operation
5.1
5.2
5.3
General Information
Pre-use Disinfection
Cleaning and Operation
17
17
17
- 1 -
Contents (continued)
6
Bottle Filling Machines
6.1
6.2
7
8.3
8.4
8.5
8.6
General Information
Pre-use Checks and Disinfection of the Bottle Washer
Operation and Cleaning of the Bottle Washer
Cleaning of Milk Bottle Crates
20
20
20
21
General Layout and Workflow
Structural Requirements
8.2.1 Floors
8.2.2 Walls
8.2.3 Ceilings
8.2.4 Doors/ Windows
8.2.5 Ventilation
8.2.6 Lighting
8.2.7 Hand-washing Facilities
8.2.8 Equipment/ Installations
8.2.9 Protective Clothing/Changing Facilities
8.2.10 Storage of Cleaning Equipment and Materials
Bottles and Containers
Equipment
Water Supply
Pest Control
22
22
22
22
23
23
23
23
23
24
24
25
25
26
26
27
Sampling
9.1
9.2
9.3
10
18
18
18
18
19
Structure and Equipment
8.1
8.2
9
Pre-use Disinfection and Operation
6.1.1 Disinfection with Cold Chemical Solution
6.1.2 Disinfection with Hot Water
6.1.3 Disinfection with Steam
Bottle Filler Cleaning
Bottle Washing
7.1
7.2
7.3
7.4
8
Page
Sampling of raw milk
Sampling of finished products
Submission of samples/Unsatisfactory results
28
28
28
Pasteurising Equipment
10.1
10.2
10.3
10.4
10.5
The Pasteurisation Process
Schematic Diagram of a Pasteuriser showing Heat Exchanger
Regeneration
Diagram of the Relevant Parts of a Typical Small-Scale Pasteurising Unit
Components of a Pasteurisation Unit
10.5.1 Balance Tank and Float
10.5.2 Pump
10.5.3 Flow Controller
10.5.4 Heat Exchanger
10.5.5 Holding Tube
10.5.6 Temperature sensor
10.5.7 Flow Diversion Valve
10.5.8 Control Panel
References
Appendix A
29
29
29
30
30
30
30
31
31
31
31
31
32
33
Pasteuriser Performance Report
- 2 -
34
INTRODUCTION
This guidance document is intended for the use of food safety
officers involved in the approval, audit and inspection of High
Temperature Short Time (HTST) pasteurisation plants in on-farm
dairies.
The document contains advice on good practice that is accepted
by the Lancashire Food Officer Group, the Greater Manchester
Food Liaison Group and the West Yorkshire Principal Food
Officer Group.
The Guide should be used in conjunction with the “On-farm Dairy
Premises Inspection Sheet” produced by the above Groups.
Additional information on routine sampling is contained in the
document: “Guidance Note for Sampling and Examination of Milk
and Cream” issued by Food and Environmental Microbiology
Services, North West Laboratory, Preston.
- 3 -
APPROVAL & REGISTRATION OF PREMISES
On-farm dairies may require Approval in accordance with EC Regulation
853/2004. Detailed information on the Approval process and premises and the
exemptions contained in the regulations is given in the Code of Practice and
Practice Guidance issued by the Food Standards Agency.
Premises requiring Approval
To gain approval under EC Regulation 853/2004 the Food Business Operator
must comply with the requirements of the relevant Regulations and in particular:
Regulation EC 852/2004: on the hygiene of foodstuffs
Regulation EC 853/2004: laying down specific hygiene rules for food of
animal origin, Article 4 Registration and Approval of establishments
An application for Approval must be submitted using the appropriate form as
specified in Annex A11.1 of the Food Standards Agency Practice Guidance
(Application for Approval of a food business establishment subject to Approval
under Regulation EC 853/2004) and must include all of the information detailed
in Part 8 of the form (Information and documentation).
Premises exempt from Approval
Premises which are exempt from Approval must be registered with the Local
Authority and must comply with the requirements of Regulation EC 852/2004: on
the hygiene of foodstuffs
Only when the premises have satisfied the above provisions and the officer is
satisfied that the dairy plant can be operated safely following pre-use
commissioning and testing should milk be processed for sale.
It is recommended that the Food Business Operator should obtain assistance
from a suitably experienced consultant.
- 4 -
1
COMMISSIONING OF PASTEURISERS
1.1
Introduction
The equipment should be installed by a reputable, competent dairy engineer, who, upon
completion of the installation and testing of all the plant, should produce a Pasteuriser
Performance Report (Appendix A).
The testing should take account of the
manufacturers specifications.
It is recommended that the dairy engineer is met on site by the Food Business Operator
and the Local Authority officer, who should satisfy themselves that the testing and
installation has been undertaken correctly.
The Food Business Operator should be encouraged to provide the dairy engineer with
details of the tests to be carried out, in advance of the visit. The operator/ officer must
ensure that the engineer has the skills necessary to carry out the tests, and to ensure
that the equipment required to undertake the tests is brought to the dairy. (N.B. 1.2.2
Holding Time Test)
1.2
Documentation
The food business operator must put in place and maintain HACCP based procedures
to comply with Article 5 of EC 852/2004. These must be appropriate to the size of the
business and must include suitable records.
The documentation should cover the operation of the equipment, detailed cleaning
procedures and arrangements for the withdrawal of products where food is not in
compliance with food safety requirements.
It is strongly recommended that the Food Business Operator should contact a dairy
hygiene consultant, who can assist in the production of these documented procedures.
1.3
Training
The person within the business who is responsible for the implementation and
maintenance of the written procedures detailed above, must have received suitable
training on their operation and maintenance. This may be by attendance at a “formal
training course” or in the form of “one-to–one” training provided by a consultant.
In addition, all other food handlers/ operatives must be trained supervised and/ or
instructed in food hygiene matters appropriate to their role. It is recommended that
training should be at least six hours long. A.D.A.S. offer a suitable training course which
will satisfy these requirements.
1.4
Pre-Production Testing
Initial pre-production testing should be carried out using water. Only when these checks
have been carried out satisfactorily should a test with milk be conducted.
1.4.1 Flow Rate
Each pasteuriser is designed by the manufacturer to process a quantity of milk
over a given period, this is known as the flow rate.
If the flow rate is too great milk will pass through the holding tube too rapidly and,
although the milk may reach 72 oC, it may not be held at this temperature for the
required 15 seconds, resulting in under pasteurisation.
- 5 -
If the flow rate is too slow, this may cause the milk to be in contact with the heat
exchange plates for too long, resulting in the milk being over heated and giving
rise to caramelisation of the milk. In addition, slow flow rates can lead to milk
deposit forming on the plates thereby reducing their efficiency and leading to
cleaning problems. (The manufacturer or the installer should be able to provide
details of the flow rate).
The flow rate can be calculated, by measuring the time taken to fill a 10-gallon
container, (i.e. a milk churn) with the pasteuriser operating on the “processing”
setting. This should be done with water running through the machine to prevent
wastage of milk. The following calculation will give the flow rate:
60 X 10
= Flow rate (gallons/ hour)
Time in minutes
Examples of flow rates are given below;
Mins to fill a
10 gallon churn
5.45
3.87
3.00
2.00
1.35
Flow Rate:
Gals / hr
110
155
200
300
444
Flow Rate:
Litres / hr
500
700
900
1350
2000
Most pasteurisers have a flow restrictor (flow controller) to reduce pressure
from the milk pump and ensure that the flow rate through the pasteuriser results
in the correct holding time.
With some units, the flow restrictor is removed during cleaning to increase the
flow rate and turbulence of the cleaning fluid and improve cleaning. It is
essential that it is reinstalled before processing begins as failure to do so
would result in an increased flow rate an inadequate holding time and underpasteurisation of the milk. This is a common cause of phosphatase failure.
Similarly, where the flow rate is adjusted by a valve, it is essential that the valve
is correctly set before pasteurisation begins.
Where a separator or homogeniser is being used, an additional flow restrictor
may be required at the take-off point. Again, this is required to prevent an
increase in flow rate which would lead to a reduction in holding time and underpasteurisation of the milk.
Where the pasteuriser is fitted with a filter, this must be cleaned/ replaced
regularly as debris can cause a blockage resulting in a reduced flow rate.
Flow rate should be checked (a) When processing whole milk only (b) When
Homogenising, (c) When separating.
- 6 -
1.4.2 Holding-Time Test
A methylene blue dye test, (or other approved method) must be carried out to
ensure that it takes at least 15 seconds for the liquid to flow through the holding
tube. This involves introducing the dye at a point close to the start to the holding
tube and, using a stopwatch, to monitor the time it takes for the dye to show at a
sample point at the end of the holding tube. A specialist engineer using
approved equipment will be required to conduct this test.
1.4.3 Calibration of Thermometers and Temperature Recorders
In order to comply with Article 5 of EC 852/2004:
a)
There should be indicating thermometers to monitor the temperature of milk
at the end of the holding tube and also at the end of the cooling section.
b)
Pasteurisers must be fitted with a thermograph to keep a permanent record
of the following information:
 A record of the temperature of milk at the end of the holding tube,
(usually a red pen);
 A record of the temperature of milk after the cold section, (usually a blue
pen); and
 A record of when the flow diversion valve has been activated, often
known as the event pen, (usually a green pen).
The recording equipment should be checked to ensure that it leaves a clear trace
on the chart. Where pens are used, it is good practice for the dairy operator to
have a spare set of pens available so that they can be changed over as soon as
the trace becomes faint.
All monitoring thermometers and thermograph recorders should be calibrated, by
a competent person, to ensure their accuracy. If the thermometers and
thermographs are not accurate it will not be possible to ensure that the milk is
achieving 72oC at the end of the holding tube, and 6oC or below at the end of the
cold section.
All indicating thermometers and thermographs should be
rechecked and calibrated on an annual basis or at such frequency prescribed by
the manufacturer. All calibration certificates must be kept and made available on
request during an inspection.
1.4.4 Operating Temperature of the Pasteuriser
To provide a margin of safety, the operating temperature of the pasteuriser
should normally be set at 73oC.
It is recommended that the temperature of incoming raw milk should be at a
constant temperature but should never be above 5oC. If the milk is too cold, i.e.
1oC then this may require too much energy from regeneration and heater
sections and, consequently, the milk will not reach pasteurisation temperatures
at the holding tube and the flow diversion valve will be activated.
If the temperature of the incoming milk is too warm, pasteurised milk on its return
from the holding tube will not be cooled sufficiently within the regeneration
section. This may lead to the growth of bacteria.
- 7 -
1.4.5 Positioning of the Flow Diversion Valve.
The flow diversion valve must be situated at the end of the holding tube. If the
valve is fitted elsewhere, e.g. at the end of the heat exchanger, then, in the event
of milk not reaching the necessary temperature at the end of the holding tube,
under-processed milk will contaminate the internal surfaces of the regeneration
and cold sections of the heat exchanger. When the temperature rises, and the
flow diversion valve opens, pasteurised milk may become contaminated with
residues of the under-processed milk that remains in the heat exchanger
following the flow diversion event.
If the flow diversion valve is situated at the end of the heat exchanger, a
competent dairy engineer must be used to reposition the valve at the end of the
holding tube. This modification must be carried out before Approval is granted
for new units. Where the above situation is identified on an operational
pasteuriser, enforcement action must be taken (E.g. service of Hygiene
Improvement Notice).
1.4.6 Flow Diversion Valve Test
The flow diversion valve must be tested at the start of each pasteurisation run to
ensure that it will operate if the milk leaving the holding tube falls below 72 o C.
The test should be taken during the warm up cycle while the unit is filled with
water, with the pasteuriser at operating temperature and the unit switched to
“automatic”/ ”processing”. The temperature of the pasteuriser should be allowed
to fall by turning off the hot water pump, turning off the hot water heater or
operating a current cut-out switch.
Observation of the hot indicating
thermometer should be made to determine the temperature at which the flow
diversion valve operates, and the temperature noted must be recorded.
The flow diversion valve test will also allow the correct positioning of the flow
diversion pointer on the rotary type thermograph. This pointer may be disturbed
during replacement of the thermograph chart and frequently does not correlate
with the scale on the chart. Therefore, the thermograph hot indicator (red pen)
should not be relied upon for this check as the needle is often disturbed when the
chart is replaced.
The flow diversion valve should be set to operate at least 0.5 o C above the
minimum legally required pasteurising temperature in order to provide a safety
margin.
Alfa Laval machines may need to have a heater cut-out switch fitted which will
allow the heater to be turned off to allow the temperature of the water to fall
naturally and an accurate test of the temperature of activation of the flow
diversion valve to be performed.
The use of a homogeniser can cause problems with flow diversion events. The
physical energy generated during homogenisation can increase the temperature
of the milk by 4 - 6 oC. To compensate for this, the temperature of the heating
section needs to be reduced to prevent the milk from over heating.
If the temperature of the heating section is not increased again when the
homogeniser is turned off, this will lead to the milk temperature falling below 72
o
C and the flow diversion valve operating.
- 8 -
1.4.7 Heat Exchanger Integrity
Manufacturing problems, use of incorrect cleaning products, abuse by the
operator, or damage during installation can result in defects in heat exchange
plates or the gaskets between them. If any of the plates or gaskets in the
regeneration section are damaged, raw milk can contaminate the pasteurised
milk at the opposite side of the plate. Milk pumps are positioned at the entry
point of the pasteuriser and push the milk through the equipment. Therefore, the
pressure is always higher in the inward (raw milk) side. Any defect in a heat
exchanger plate in the regeneration section is likely to result in raw milk being
forced through from the inward side to the outward side and contaminating the
pasteurised milk.
Where phosphatase failures occur, if there are intermittent failures or where
results show adverse trends (an increase in phosphatase levels over a period of
time) tests to check the integrity of the heat exchanger unit must be considered.
These should only be carried out after the pasteurising temperature and holding
time/ flow rate have been checked.
There are a number of specialist companies which carry out plate testing, to
detect faults using differing methods. These include: conductivity testing and the
use of helium gas with the plates in situ, and the traditional method of inspection
which involves splitting the plate banks to allow a physical examination of the
individual plates using a “light box” or by painting them with a dye solution.
Whenever the heat exchanger is dismantled and rebuilt, it is recommended that
samples should be taken from a minimum of 3 successive batches of milk and
submitted to the laboratory for phosphatase testing. Samples should be taken
from the beginning, middle and end of a production run lasting not less than 30
minutes.
1.4.8 Volume of Liquid in the Plant
The volume of liquid in the plant needs to be established to ensure that the
correct concentrations of cleaning and disinfection chemicals are used. Most
cleaning chemical manufacturers produce product data sheets, which specify a
dose rate per litre of fluid. “Under dosing” may lead to ineffective cleaning and
disinfection whilst “over-dosing” may cause damage to the plant or lead to
difficulties in rinsing the plant effectively.
1.4.9 Pressure Checks
If the pasteuriser has a pressure gauge, the Food Business Operator must be
aware of the correct operating pressure for the machine. Falling pressure may
indicate a problem with the pump, flow restrictor, filter or a build up on the heat
exchange plates.
1.4.10 Ancillary Equipment
Cream separators and homogenisers must be compatible with the flow rate of
the pasteuriser. If the ancillary pieces of equipment have a greater flow rate,
they may create a negative pressure drawing the milk through the holding tube at
an increased rate leading to a reduced holding time and under pasteurisation.
Flow diversion may not occur with an increased flow rate as the temperature at
the hot sensor, located at the end of the holding tube, may be above 72 oC.
In many on-farm dairies, whole milk is separated to produce skimmed milk and
cream. To do this, warm milk is taken from the pasteuriser part way through the
process, as warm milk separates more effectively than cold milk which has left
- 9 -
the unit. It is essential that the “take off” point from the pasteuriser is on the
outward side of the machine i.e. after the holding tube so that pasteurised milk is
separated. If the cream take-off is positioned on the inward side of the
regeneration section this will result in the production of pasteurised skimmed
milk, (providing the skimmed milk is returned to the regeneration section after
skimming), but raw cream, and a separate cream pasteuriser will be required.
1.4.11 End Product Testing on Completion of Commissioning
When all of the above checks have been completed using water, a preproduction test run with milk should be carried out. It is recommended that the
test run should be for not less than 30 minutes. Samples from the start, middle,
and end of the process run for all types of milk produced, (whole milk, semiskimmed, skimmed milk), and cream, in all types of finished product containers,
should be taken for phosphatase and enterobacteriaceae testing.
The operator should be informed that this pre-production run is for test purposes
only. No processed milk may be sold from the new premises until all test results
have been received and are satisfactory, and the Approval Number has been
issued.
[Note: Contact should be made with the testing laboratory to arrange for the
testing of the samples prior to obtaining them. A charge may be made for
undertaking these tests which should be borne by the Food Business
Operator.]
1.5
Routine Maintenance and Calibration of the Pasteuriser
A service contract should be set up with a reputable dairy engineer to carry out the
checks detailed on the Pasteuriser Performance Report (see Appendix A), at least once
every 12 months.
Ideally, in the first year of the contract, consideration should be given to arranging for
the dairy engineer to check all instruments after one month, followed by a full service
after 6 months. This should include all of the checks detailed on the Pasteuriser
Performance Report.
An external visual examination of the heat exchangers should be made. Signs of
leaking milk may indicate the need for new gaskets. Replacement of plates and gaskets
should be carried out at the frequency advised by the competent service engineer. The
service engineer should have regard to the age, amount of use the machine has had
and any additional factors which may necessitate the early replacement of plates,
gaskets or other components. Homogenisers can cause additional stresses leading to
components wearing out at a faster rate. The service engineer should also have regard
to the manufacturer recommendations as to when components should be replaced.
Opening of the pasteuriser heat exchanger plates by the dairy Food Business
Operator must be discouraged as damage can occur whilst the plates are being
repositioned and the plate pack re-tightened. In particular “over-tightening” of the heat
exchanger unit can cause serious damage to the heat exchanger plates. Adjustments
must only be carried out by a competent engineer.
1.6
Routine Maintenance of Other Dairy Equipment
Other plant should be serviced in accordance with the manufacturer instructions.
Should these be unavailable then the engineer should be consulted as to the necessary
servicing intervals and preventative maintenance.
- 10 -
2
CLEANING AND OPERATING PROCEDURES
2.1
General Information
All equipment, containers and pipework which come into contact with dairy products
must be cleaned and, if necessary, disinfected according to a cleaning programme
based on hazard analysis principles.
It is essential that the correct chemicals are used, in the right concentrations, at the
correct temperatures, and for the contact times specified by the manufacturer of the
cleaning and disinfection chemicals.
It is essential that the cleaning and disinfection chemicals used are appropriate for the
chemical composition of the water at the premises as some chemicals are formulated for
use specifically in hard or soft water areas.
Cleaning procedures must take into account the plant used, its layout, facilities and the
cleaning chemicals used by the Food Business Operator. They should include a stepby-step guide how to pre-disinfect, use and clean and disinfect all plant and equipment
in the dairy.
For easy reference, cleaning procedures can be laminated and displayed behind the
piece of equipment to which it relates.
If followed correctly these schedules are usually effective. Problems occur when the
Food Business Operator deviates from the schedules or uses a new cleaning product,
which requires a different dose rate or time/ temperature combination to the chemical
used previously.
Food Business Operators should review their cleaning schedules regularly, particularly
after any change in cleaning products, and amend them as necessary.
2.2
Cleaning, Inspection and Disinfection of Filters
Filters may be either a reusable mesh gauze or a disposable cloth/ paper unit. Where
fitted, they must be cleaned, inspected, and disinfected prior to operation of the unit.
2.3
Pre-use Disinfection and Start-up Procedure
Although pasteurisers will normally be cleaned after use, they must also be disinfected
immediately before the next production run. The purpose of this is to reduce the levels of
any bacteria which may have survived the cleaning process to a safe level.
The most common methods are either by hot water (hot start up), or by the use of a
chemical solution (cold start up). The preferred method is using hot water, however, in
some units the heating unit is not capable of raising the temperature of the water
throughout the whole of unit to the required temperature so a cold start-up is used.
Prior to disinfection, the plant must be fully assembled and the thermograph recorders
should be operating. A new thermograph chart should be inserted, if necessary, dated
and signed by the Food Business Operator.
Air vents if fitted (usually at the top of the holding tube), should be opened to release any
trapped air and to ensure the thorough wetting of all internal surfaces. These vents
should be closed when liquid is running freely from them.
- 11 -
During pre-use disinfection, the hot water or cold chemical solution from the
pasteuriser, may be used to disinfect ancillary equipment such as the homogeniser or
separator. In the case of a cold start up any additional amount of liquid involved
should be considered when calculating the strength of the disinfectant solution
2.3.1 Hot Start-up
To ensure adequate disinfection, a hot start-up requires a minimum
temperature of 75 oC, throughout all sections of the plant, for not less than 15
minutes. It is imperative that all of the heat-exchanger plates reach this
temperature and not just the hot holding section. To achieve this, it is
necessary to turn off the supply of cold water/ coolant to the cooling section of
the heat exchanger unit. The temperature can be checked using the cold pen
on the thermograph, or the cold end thermometer.
If difficulties are encountered when attempting to raise and maintain the
temperature throughout the equipment, steam can be added to the balance
tank to boost the temperature, if available.
If there are long sections of pipe work after the outlet from the pasteuriser
then temperature may be lost resulting in ineffective disinfection. In this case,
a cold start up may be preferred.
2.3.2 Cold Start-up
The cold start up method requires the cold circulation of hypochlorite at a
strength of 100ppm for at least 10 but no longer than 20 minutes. Hot water
must never be used with hypochlorite as it has a corrosive action on the
stainless steel heat exchange plates. Only fresh preparations of
hypochlorite should be used and the product must be within its
manufacturer shelf life to ensure the correct concentration of available
chlorine for disinfection.
Before milk is introduced, the plant must be thoroughly rinsed using cold clean
water in order to remove the residues of the disinfectant.
2.3.3 Cleaning of the Flow Diversion Valve
During the pre use disinfection, the flow diversion switch should be manually
activated frequently, in order to clean the valve, seating and associated pipe
work.
2.4
Other Start-up checks
2.4.1 Fitting/ Setting of the Flow Restrictor.
A check must be made that the flow restrictors are in place or set correctly.
2.4.2 Visual Inspection of the Pasteuriser
If the gaskets are leaking then this indicates that they may need to be
replaced. A dairy engineer should be contacted without delay. Tightening of
the plate pack should be discouraged as over tightening can result in
distortion or damage to the plates.
- 12 -
2.4.3 Flow Rate Test
A flow rate test should form part of the annual maintenance check. In addition, it
should be checked at least every month by the Food Business Operator and a
record of the result made (see Para 1.4.1). Where the flow rate is found to be
above that stated in the Pasteuriser Performance Report (see Appendix A), the
equipment should not be used until it has be examined by a competent engineer.
2.5
Operation of the Pasteuriser
Once pre-use disinfection is complete, and the equipment is full of clean water, the
heater elements should be switched on and water circulated around the system until the
normal operating temperature is reached.
Before milk is introduced, the flow diversion valve must be tested as detailed in 1.4.6.
The thermograph and indicating thermometer should be checked to ensure that the flow
diversion valve is operating at the correct temperature. The thermograph should then be
signed and dated by the operator. Where necessary, adjustments should be made to the
flow diversion pen, so that it operates at the correct temperature.
All thermographs must have sufficient chart space for the full days production run. They
must not be allowed to ‘over write’, as an accurate record will not be produced of the
processing.
The hot and cold temperatures on the thermograph must be checked and verified using
the indicating thermometers. The pressure gauges, if fitted, should also be checked.
When the temperatures have stabilised processing may begin. When milk is introduced,
the first milk to show at the pasteuriser outlet will contain water. Sufficient milk must be
run to waste to prevent milk for bottling becoming diluted with water.
Running time must not exceed 6 hours as long running times result in milk deposits
collecting on the heating surfaces leading to ineffective heat exchange and difficulties in
cleaning.
2.6
Pasteuriser Cleaning following a Production Run
At the end of the production run, the milk should be displaced from the equipment by
running cold water through the plant. When clean water appears at the pasteuriser
outlet, the flow of water should be returned to the balance tank and circulated for a
period of not less than 10 minutes. If the circulating water is heavily contaminated with
milk residues, the system should be refilled with clean water.
Detergent should now be introduced into the plant via the balance tank and circulated
within a closed circuit at 70-80oC for 20 minutes. The time, temperature and chemical
strength recommended by the manufacturer must be followed. The strength of the
caustic should be around 2% concentration and be added to the balance tank gradually
to ensure an evenly mixed volume is circulating around the equipment. Adding all the
caustic at one time could form a plug of chemical that will take a long time to disperse
evenly throughout the circulating water. After long processing runs the contact time and
the concentration may need to be increased.
Where fitted, the flow restrictor must be removed or adjusted to increase the flow rate
and improve cleaning. A flow rate of 10% above processing flow is desirable.
It is essential that the volume of liquid in the equipment is known so that the correct
strength of caustic required for cleaning can be calculated. For example, if the volume is
- 13 -
300 litres – 6 litres of caustic will be required to give a 2% concentration, providing the
caustic is supplied at 100% concentration. However, most caustic is supplied at around
33% concentration, therefore, using the previous example, three times as much must be
added i.e. 18 litres, to arrive at a 2% concentration. Powdered detergent must never be
introduced directly into the balance tank, it must always be pre-mixed with water in a
stainless steel or plastic bucket prior to being used in the plant.
If additional pipe work or ancillary equipment is cleaned in-line with the pasteuriser, then
the extra volume of liquid involved should be included when calculating the concentration
detergent required.
The hot cleaning solution should be circulated through the pasteuriser and all
interconnecting pipe work and fittings. The cleaning time should be measured from the
time the fitting or pipe work at the most distant point on the pasteuriser cleaning circuit
reaches over 80oC. A common mistake is to measure the cleaning time from the time
the thermometer and thermograph indicate that the temperature at the end of the
holding tube is at above 80oC.
During circulation of the cleaning solution, the surfaces of the balance tank above the
detergent level should be brushed to remove any contamination.
At end of the cleaning cycle the flow diversion valve should be allowed to automatically
divert on a falling temperature so that it is cleaned by circulation for a minimum of five
minutes.
When the cleaning cycle has been completed, the detergent solution must be flushed
out with clean, cold water.
2.7
Cleaning Records
Most plants, (apart from the Alfa Laval Microtherm machines), have the facility to monitor
and record the times and temperatures at the hot and cold end of the pasteuriser during
cleaning. The Alfa Laval Microtherm machines, however, wash using the “automatic”
and the thermograph does not operate. A manual check will need to be made of the
temperature of the solution returning to the wash tank. This should be recorded on a
daily process sheet.
2.8
Acid de-scale
With current detergent formulations acid descaling should not be necessary. Should a
build up of milk deposit occur then an alternative detergent system should be
considered.
Checking the difference between the temperature of the hot water and that of the milk
can identify a build up of ‘milk stone’ deposit on the heat exchanger plates. Normally the
difference will be about 4 oC. If it is much greater than 6 oC then this would probably
indicate a build up of solids on the plates making heat transfer more difficult and thus,
automatically increasing the hot water temperature in compensation.
In this case an acid de-scale would be needed in addition to normal cleaning. Advice
from the plant manufacturer and the chemical supplier must be sought before
undertaking this operation.
After the acid de-scale the plant must be rinsed thoroughly with cold clean water,
followed by a final weak alkaline solution, equivalent to 0.1% solution of sodium
hydroxide. This will prevent damage to stainless steel plates.
- 14 -
3
PASTEURISED BULK MILK TANKS and CHURNS
3.1
Pre-use Disinfection
Tanks can be disinfected using cold chemical solution, hot water, or steam. The
manufacturer instructions for the cleaning and disinfection of non-metallic or aluminium
tanks should be sought. If the tank is cleaned with a combined disinfectant/ detergent
then pre-use disinfection will not be required, providing the tank is used immediately. If
the tank is not used for a period of more than four hours, a further pre-use disinfection
will be required.
Chemical disinfection with hypochlorite, followed by a clean water rinse, is the most
commonly used method. If a “clean-in-place” system is used then the spray ball must be
suitably located to ensure the thorough wetting of the internal surfaces of the tank.
3.2
Cleaning
After emptying all milk from the tank, the internal surface of the tank should be rinsed
with clean cold water and the surfaces scrubbed to remove all stubborn milk residues.
The tank should then be cleaned using a suitable detergent, (this is often in the form of
a “pink powder”). Special attention should be paid to the inlets, outlets, gaskets and
other fittings the tank may contain. Flush the tank thoroughly with clean water to remove
all detergents/ disinfectant.
The agitator paddle and other fittings should be removed and dismantled each time the
tank is cleaned.
3.3
Churns
If churns are used for storage or transport of milk the Food Business Operator should
use disposable churn liners.
- 15 -
4
CREAM SEPARATOR CLEANING AND DISINFECTION
4.1
Disinfection of the Cream Separator.
The separator must be disinfected immediately prior to use to reduce bacteria to a safe
level and to prevent contamination of the pasteurised milk.
The cream separator can be disinfected separately or in-line with the pasteuriser during
a hot or cold start-up, using the hot water from the pasteuriser during the disinfection of
the unit or hypochlorite solution. After disinfection with a chemical solution the machine
should be rinsed using clean cold water.
Care must be taken that the separator reservoir is given sufficient contact time, over all
the internal surfaces, to ensure effective disinfection. (At least 10 minutes for cold start
up and 15 minutes for a hot start up).
4.2
Cleaning of the Cream Separator
Separators should be cleaned following the manufacturer instructions:
At the completion of use, the separator should be rinsed using water at between 40 oC
and 50 oC until the water runs clear.
The bowl and disks must be dismantled. The disks should be scrubbed, with a nylon
brush, using a mild detergent solution, (usually supplied as ‘dairy detergent’), again at
40oC - 50oC. If any “milk stone” has developed, an acid de-scale may be necessary,
following the manufacturers instructions
After cleaning, the components should be dried and stored in a clean place or may be
left overnight in clean water prior to reassembly immediately prior to the next production
run.
- 16 -
5
HOMOGENISER PRE-USE DISINFECTION AND OPERATION
5.1
General Information
The instructions given by the manufacturer of the plant must be followed carefully, as
the high strength stainless steel used in some units may be susceptible to corrosion.
The detergent solution must be free of all undissolved particles as these may cause
damage to the piston seals and homogenising valves.
5.2
Pre-use Disinfection
Pre-use disinfection must be carried out immediately before the plant is used.
The preferred method for disinfecting homogenisers before use is with hot water, due to
potential corrosion problems of using chemical disinfection solutions. Processors may
have difficulties in achieving and maintaining the required temperature due to the energy
it can take to heat the large metal mass of the plant.
The pressure from the homogenising valves must be released. Hot water must be
circulated for at least 20 minutes after its return temperature reaches 80 oC.
If there is no alternative to the use of a cold chemical solution, the advice of the
manufacturer must be sought and followed rigorously.
5.3
Cleaning and Operation
Following processing, the plant must be rinsed with clean cold water to remove all loose
milk residues.
In most cases the homogeniser is cleaned “in line” with the pasteuriser. The time,
temperature and causticity combinations specified by the manufacturer of the cleaning
chemical must be followed.
The pressure of operation of the homogeniser should be reduced to approximately 550
kN/m2, as indicated by the pressure gauge.
Following cleaning, the machine should be rinsed with clean cold water. This pre and
post clean rinsing with clean cold water should be limited to approximately 3 or 4
minutes, as water is a poor lubricant, and operation of the plant with water can lead to
excessive wearing of the components.
If recommended by the manufacturer, the pressure gauge, homogenising valves and
any standpipe pressure pulsation damper should be removed and inspected for
residues. If necessary, manual cleaning with a suitable hand washing detergent or
combined detergent disinfectant should be carried out at temperatures of approximately
60 oC and no lower than 45oC. The components should be thoroughly rinsed with clean
cold water and the machine should be reassembled using clean hands.
- 17 -
6
BOTTLE FILLING MACHINES
6.1
Pre-use Disinfection and Operation.
Before use the bottle filler must be disinfected using a hypochlorite solution, hot water, or
steam. The pipelines used to pass the products to the filler should be included in this
process.
The manufacturer of the plant should be consulted for the best method of disinfection to
use as disinfection by hot water or steam may not be suitable for all machines.
Initial disinfection of the filler valves and the filler head rubbers should be carried out by
immersing them in a 20 mg/ litre hypochlorite solution for 2 hours. Adding 1ml of
hypochlorite to 5 litre of water can produce this concentration. The valves and rubbers
must be rinsed with cold clean water.
Hairline cracks in filler valves or poor welding/ soldering at the fitting point for the valves
can leave fissures which can not be cleaned or disinfected effectively, resulting in
samples failing to meet the legal standard. In this case, new valves or improved welding/
soldering may be needed.
Pre use disinfection should be carried out as close to the time of filling as possible.
6.1.1 Disinfection with cold chemical solution
The rubbers should be reassembled using clean hands. All surfaces should then
be thoroughly wetted with disinfectant solution and allowed to stand for between
10 and 20 minutes.
The solution should then be run through the filler valves and heads. The filler
bowl, valves and heads must be rinsed with clean cold water before use and the
first few bottles filled should be discarded as they may contain some of the rinse
water.
6.1.2 Disinfection with hot water.
The disinfected rubbers should be reassembled using clean hands.
Hot water at above 75oC should be introduced into the filler bowl. Once the filler
bowl is full the valves should be opened and hot water should be introduced at a
rate that allows the bowl to remain full during this process. The hot water should
be allowed to flow through the valves at this temperature for at least 15 minutes.
6.1.3 Disinfection with steam
The disinfected rubbers must be reassembled using clean hands.
Clean steam should be injected into the filler in accordance with the
manufacturers instructions.
- 18 -
6.2
Bottle Filler Cleaning
At the end of the production run the filler bowl should be drained and rinsed with cold
water
All removable fittings should be dismantled e.g. air pipes, filling rubbers, valves and
these should be washed separately with a solution of detergent at 40oC - 50oC.
Particular attention must be paid to valve stems.
The filler bowl should be scrubbed with a detergent solution at 50oC, rinsed and
reassembled using clean hands. The equipment should be left covered until pre-use
disinfection shortly before the machine is used again.
The cap forming die and sealing head must also be cleaned and disinfected following the
manufacturers instructions.
Where a vacuum system is fitted to assist with the rapid filling of the bottles by removing
air, this must be cleaned and disinfected between each production run following the
manufacturers instructions.
- 19 -
7
BOTTLE WASHING
7.1
General Information
One of the most common causes of intermittent microbiological failure is ineffective
washing and disinfection of bottles, or bottles being washed too far in advance of being
filled.
Some small on-farm processors may have bottles washed off the premises, at a remote
site owned by a larger processor. The smaller processor has no control over the
washing and disinfection of the bottles. After cleaning, they are transported to the dairy,
on occasions ineffectively protected from contamination from the environment. This
practice, should be discouraged.
Bottles must be washed in accordance with the instructions supplied by the bottlewasher manufacturer using chemicals for the appropriate time, temperature and
concentrations as recommended by the chemical manufacturer.
7.2
Pre-use Checks and Disinfection of a Bottle Washer.
The bottle washer should be cleaned and disinfected daily.
All jet manifolds must be brushed to remove deposits and the jets checked to ensure that
they are not obstructed. Where necessary they can be cleared using a piece of fine wire.
The rinse tank should be emptied and hosed out daily using clean cold water.
7.3
Operation and Cleaning of a Bottle Washer.
Bottles should be inspected before they are put through the bottle washer. Grossly
soiled bottles should be removed and disposed of carefully.
Detergent solutions should be totally changed or topped up at regular intervals, to
maintain the concentration specified by the manufacturer of the unit or chemical supplier.
When the detergent solution is changed the tanks should be thoroughly cleaned and
hosed out.
Detergent should be added to the wash tanks and hypochlorite to the rinse tanks to
achieve the manufacturer’s recommended concentrations. The manufacturer will also
indicate the temperature range in which the detergent and the heat will act as a
disinfectant. The temperature of the wash tanks and the concentration of the chemicals
used are critical to ensure bottles are effectively cleaned and, therefore, maintain the
safety of the product.
Records should be kept of the operating temperature of the tanks and that the tanks
have been dosed and topped up if necessary during washing.
Detergent solutions will become diluted during the washing process and may require
topping up to maintain the correct concentration. If the processor does not have titration
facilities, automatic metering or other testing equipment, a general guide is to re dose as
per the cleaning chemical manufacturer recommendations after 25 - 50 crates of bottles
have been cleaned.
- 20 -
7.4
Cleaning of Milk Bottle Crates
Each crate should be washed between use.
Most bottle washers are ‘in crate’ washers and the crates are usually adequately washed
during this process.
Some bottle-washers wash the bottles out of the crate. Problems can arise when
washed and disinfected bottles are left to drain ‘neck down’ in the unwashed crates,
before being filled.
If crates are manually cleaned, they should be scrubbed inside and out with a hot
detergent solution and then rinsed with clean water.
- 21 -
8
STRUCTURE AND EQUIPMENT
8.1
General Layout and Work Flow
The size of any room or rooms in any treatment or processing establishment should take
account of all necessary plant and equipment, and include of sufficient space to allow
persons to operate the equipment safely and hygienically.
Plant and equipment should be positioned to ensure a logical, progressive flow of
product through the various stages of production and processing without any risk of
contamination,
Sufficient storage should be provided for the following:



8.2
Returned reusable containers (e.g. glass bottles) prior to washing;
New and disposable containers and lids;
Chilled finished products;
Structural Requirements
8.2.1 Floors
Floors should be laid with a suitable fall to encourage self-drainage. Ideally,
floors should incorporate suitably constructed and covered drainage channels
that connect to a trapped foul drainage outlet.
Floor finishes should be easily cleanable, non-absorbent, non-slip and resistant to
impact, heat, acids and alkalis.
A well-laid granolithic floor, with a smooth finished surface, will meet these
requirements as will a well laid quarry tile floor however, the latter is more
susceptible to impact damage.
8.2.2 Walls
Walls should be free from all unnecessary projections and indentations etc. and
well maintained.
The wall surface must be smooth, durable, non-absorbent, easily cleanable and
light coloured. The surface coating or covering will depend upon the condition of
the wall surface, i.e. where the wall surface is in good condition regular painting
with a proprietary paint with anti-fungicidal properties should suffice, but where
the wall surface is poor, suitable cladding may be more appropriate. Where
cladding is fixed care must be taken to ensure that there are no voids behind the
sheets, which could provide harbourage for pests, and that all joints are
effectively sealed.
Pipes, conduits etc. should be securely fixed and mounted clear of wall surfaces
to allow effective cleaning. Where services pass through walls they must be
properly sealed to prevent entry by pests.
Protection should be provided to exposed wall angles to minimise damage to the
wall surfaces. Wall junctions with floors and ceilings should ideally be coved to
allow easy cleaning.
- 22 -
8.2.3 Ceilings
Ceilings should be free from unnecessary ledges and protrusions and well
maintained.
The ceiling surface should be smooth, easily cleanable and light coloured. It may
be necessary to underdraw ceilings to enable a smooth surface to be achieved.
Where practicable the ceiling should be insulated to prevent condensation and an
access point to the ceiling void should be provided for maintenance and
inspection purposes.
8.2.4 Doors/ Windows
Doors and windows should be well maintained and provided with a durable, nonabsorbent, light coloured, easily cleanable surface finish.
Doors should be clad internally to provide a smooth surface and fitted on both
faces with non-corrodible metal kick plates to a minimum depth of 150mm (6”).
Closed doors should fit closely at the base with the sill or floor surface and at the
edges with the jambs, to ensure that any gap does not exceed 10mm (3/8”). All
opening windows should fit tightly when closed.
All and opening windows should be fitted with fine mesh screening to prevent
entry by flying insects. Overlapping strip curtains should be fitted to external
doors. Ideally screening should be removable for cleaning purposes.
Internal window sills should ideally be sloped at an angle of approximately 30o to
prevent items being stored on them and assist with cleaning.
8.2.5 Ventilation
Adequate ventilation must be provided. Mechanical extraction ventilation with
inlets sited above major steam sources e.g. bottle washers, should be installed.
Consideration should be given to the siting of ventilation outlets in relation to the
position of opening windows and doors to ensure ‘short circuiting’ of incoming air
does not occur.
8.2.6 Lighting
Adequate artificial lighting must be provided, for example, by means of
fluorescent lights. Ideally these should be fitted with diffusers to prevent products
becoming contaminated in the event of a bulb becoming damaged.
8.2.7
Hand washing facilities
An adequate number of wash hand basins should be provided in processing
areas in locations which are easily accessible for food handlers and also in the
sanitary accommodation. These must be:

supplied with hot and cold water (or pre-mixed water at a suitable
temperature) from taps which are preferably not hand or arm operated;

provided with sufficient supplies of bactericidal soap;

drained by carrying the water directly in a pipe or a suitably constructed and
covered floor drainage channel connected to a trapped foul drainage outlet
- 23 -
fitted with a suitable grating or cover. Ideally hand wash facilities should not
drain directly onto the floor surface;

8.2.8
provided with disposable paper towels as a hygienic means of drying
hands. A bin with a suitable lid must be provided for used paper towels.
This must be emptied regularly.
Equipment/ Installations
Equipment or installations etc. which are cleaned-in-place (C.I.P) should always
be cleaned in accordance with the manufacturers’ instructions; e.g. with regard to
quantity of cleaning material, temperature to be attained during cleaning,
circulation times, etc.
Suitable deep sinks or wash troughs should also be provided, capable of
accommodating the largest pieces of equipment which require washing by hand.
All sinks/ wash troughs must be provided with a hot and cold water supply and
sufficient supplies of suitable detergents, disinfectants, etc. Cleaning equipment
e.g. brushes, squeegees etc. should not contain any wood. In addition, separate
colour coded equipment should be provided for cleaning equipment used for raw
milk and for cleaning equipment used for heat-treated products.
Equipment used in the milking parlour must not be cleaned in the dairy due to the
risk of cross contamination.
After use, all cleaning equipment should be left clean and dry and stored in a
designated area of the premises.
Waste water from fixed sinks should be discharged directly into a pipe or a
suitably constructed and covered floor drainage channel connected to a trapped
foul drainage inlet fitted with a suitable grating or cover.
For all cleaning situations in the dairy industry reference should also be made to:

BS5305 : 1984 ‘Cleaning and Disinfecting of Plant and Equipment used in
the Dairying Industry’; or

BS 7771:1994 ‘Code of practice for pasteurization of milk on farms and in
small dairies’
8.2.9 Protective Clothing/ Changing Facilities
All staff working in the dairy must wear suitable protective clothing. This should
consist of a clean washable overall, clean washable head covering capable of
enclosing the hair and clean washable footwear. Any other protective clothing
e.g. apron, should also be clean and washable.
Protective clothing should not be worn when carrying out any other activity which
is likely to introduce a risk of contamination. A person working in a milking parlour
should not enter a production or processing area directly, without changing
protective clothing (including footwear) and washing hands and forearms.
- 24 -
Adequate changing facilities must be provided for employees. However, by
agreement with the local authority, changing and toilet facilities may be provided
in the farmhouse.
Where provided, changing facilities should consist of at least one room,
separated from any production or processing area. The floors, walls, ceilings,
doors, windows, lighting and hand-washing facilities should be of the same
standard as detailed above. Toilets must be separated from the production areas
by a lobby which is ventilated to the external air.
Adequate natural or mechanical ventilation must be provided.
8.2.10 Storage of cleaning equipment and materials
Suitable arrangements must be made for the storage of cleaning equipment. This
should be in the form of a separate room or locker. The store should be outside
any production or processing area, but easily accessible.
Tools used for maintenance purposes etc. must not be stored in a production or
processing area when not in use.
8.3
Bottles and Containers
Unwashed bottles or other containers should not be stored in a production or processing
area prior to cleaning. Ideally, a separate building or room close to the bottle washing
equipment should be provided, for storage of unwashed bottles. The storage area
should have readily cleanable surfaces and a floor, which is smooth, non-absorbent and
capable of being kept clean e.g. smooth finished concrete.
Bottles and other containers should be brought into the bottle washing area immediately
before they are to be washed and should not pass through any production or processing
areas before cleaning.
In newly constructed dairies, areas which are completely separate from production and
processing areas should be provided for storage and cleaning of returned bottles and
containers.
Washed bottles or containers should be examined after washing and stored in an
inverted position, protected from the risk of contamination until required for refilling. The
interval between washing and refilling should be as short as possible.
Similarly, foil, foil caps, container caps and closures, labels, etc. should be stored in a
closed container in a suitable store, to minimise the risk of contamination.
New, unused bottles or disposable containers should, where practicable, be kept in a
cool, dry store separate from any production or processing area. The store should have
readily cleanable surfaces and provide protection from the risk of contamination.
Bottles and containers should be stored off the floor and kept in their original packaging
until required. Any remaining bottles or containers in opened packaging should be
suitably covered and protected from the risk of contamination.
Only the number of bottles or containers required for immediate filling should be taken
into the processing/ filling area.
- 25 -
8.4
Equipment
All plant, equipment or utensils intended to come into contact with milk or milk products
should be: 
suitable for use with such products;

of sound construction, well maintained, clean and, as far as practicable, totally
enclosed;

used for no other purpose, except the storage, production or processing of milk
or milk products.
Refrigerators (including cold stores), freezers, storage areas for products, etc. should be:

of sufficient size to accommodate maximum quantities of product requiring
storage;

located correctly to ensure that the logical flow of product is not interrupted and
there is no risk of contamination from raw to heat treated product e.g. in product
reception area, in finished product dispatch;

well constructed, well maintained and clean;

of suitable materials e.g. corrosion resistant, smooth, durable, light coloured and
easy to clean.
In addition, refrigerators (including cold stores), freezers should be: 
provided with an easily readable, calibrated indicating thermometer on the outside
of the cabinet or structure which should be read and recorded at least twice daily
by the Food Business Operator. Thermometers should be checked annually by a
competent engineer;

capable of retaining milk and milk based products at the required temperature,
(6oC or less).

fitted with flexible overlapping strips or other suitable ambient air deflection
equipment in door openings, where doors are open for prolonged periods e.g.
during loading.
Delivery vehicles (e.g. milk tankers) used for transporting milk or milk based products
must be cleaned and disinfected after each time they are used.
Where vehicles are not provided with self-cleaning mechanism suitable facilities should
be provided for cleaning and disinfection. Cleaning and disinfection should take place on
a suitable hard standing e.g. concrete, which should be laid with a fall to a trapped foul
drainage inlet fitted with a cover or grating. Tanks should be protected from any risk of
contamination following cleaning and disinfection.
Vehicles should be clearly labelled “For foodstuffs only”.
8.5
Water Supply
The water supply to the dairy needs to be considered in relation to its microbiological
safety and chemical composition. Where the supply is a private supply (e.g. from a well
spring or bore hole) or where storage tanks are used, it must be tested prior to
commencement of production and then on a regular basis. In “hard-water” areas, tests
- 26 -
for hardness will need to be carried out, as this will affect the choice of cleaning and
disinfection chemicals that can be used.
Any tanks used for water storage must be completely covered, regularly inspected and
maintained. This should include cleaning and disinfection.
8.6
Pest Control
Adequate pest control procedures must be in place. These should include building
construction and maintenance. Sealing all holes in walls and roofs; doors which fit tightly
when closed; fitting fine mesh screens to opening windows; trapped and suitably grated
drainage outlets will help to prevent entry by pests.
In addition, areas on the outside of the premises must be kept tidy and clear of
accumulations of rubbish, weeds, etc.
A reputable pest control company should be employed to regularly monitor, and treat any
infestation.
Electric fly killers should be installed close to access points into any production or
processing area to reduce the risks from flying insects. To minimise risks of
contamination, they should be sited away from processing equipment. They should be
cleaned regularly and the UV tubes changed at the manufacturers specified intervals.
- 27 -
9
SAMPLING
9.1
Sampling of Raw Milk
EC 853/2004, Annex III, Section IX, sets out requirements for the sampling of raw milk.
Where a Food Business Operator sells part of their production of raw milk to a
wholesaler, enforcement officers should take into consideration the results of any
sampling the wholesaler carries out.
Similarly, the same Regulation requires Food Business Operators to ensure that raw milk
is not placed on the market if it contains unsatisfactory levels of antibiotics. When
considering this requirement, enforcement officers may wish to take into consideration the
following:

whether all of the milk processed within the premises is produced by cows under the
control of the food business operator;

whether effective procedures are in place to control the use of antibiotics and for the
monitoring of withdrawal periods; and

where milk is also sold to a wholesaler, the results of any tests carried out by them.
Enforcement Officers may wish to implement a higher priority of enforcement of this
requirement where they have concerns regarding the above issues or where milk
intended for pasteurisation is being purchased from a third party.
9.2
Sampling of Finished Products
The Food Business Operator must put in place a sampling programme for
Enterobacteriaceae, to comply with the requirements for the microbiological criteria of
foodstuffs set out in EC 2073/2004. Annex 1, Chapter 2, Section 2.2.1.
In addition, products must also be tested for Alkaline Phosphatase activity to ensure that
they have been adequately pasteurised, as detailed in EC 1664/2006. This requires that
products should be tested for Alkaline Phosphatase using the flourimetric method. The
test is considered to give a negative result if it is not higher than 350mU/l.
9.3
Submission of Samples and Action in the Event of Unsatisfactory Results
Sampling frequency: EC 2073/2005, Article 5 states that Food Business Operators shall
determine appropriate sampling frequencies based on HACCP principles, and that these
may be adapted to the nature and size of the food business, provided that the safety of
the foodstuffs will not be endangered.
When the Regulations came into force, the Food Standards Agency advised that
sampling frequencies should not be varied from those set out in previous legislation. On
this basis, it is recommended that samples should be submitted by the food business
operator once per month for the tests set out in 9.2. This frequency should be subject to
increase or decrease based on the results of previous samples.
Samples should be submitted to suitably accredited laboratories.
The documented procedures produced by the food business operator should include the
action to be taken following receipt of unsatisfactory results and in particular the
arrangements for the withdrawal of products where food is not in compliance with food
safety requirements as required by EC 178/2002, Article 19.
- 28 -
10
PASTEURISATION
10.1
The Pasteurisation Process
Pasteurisation occurs when a product is heated to the required temperature and retained
there for a prescribed period of time. Different products require different time/
temperature combinations to achieve adequate pasteurisation.
Milk is normally pasteurised by the High Temperature Short Time method (H.T.S.T.) using
equipment which operates as a heat exchanger.
The time/ temperature combination for milk is normally 72oC for a minimum period of 15
seconds.
Milk is fed into the pasteuriser from a bulk milk storage tank. It is recommended that the
temperature of the supply milk should be constant and about 4oC.
10.2
Schematic Diagram of a Pasteuriser showing Heat Exchanger.
Cooling
Section
Milk from
Holding Tube
Regeneration Section
Hot Water In
Chilled Water Out
To Holding Tube
Cooled Finished
Milk Out
Hot Water Out
Chilled Water In
Heating
Section
Raw Milk In
10.3
Regeneration
The normal efficiency of the regeneration section of a heat exchanger pasteurising unit is
about 90%.
If milk were to be admitted to the regeneration section at 4oC and pasteurised at 74oC the
temperature of the milk would have to be raised by 70oC (i.e. 74oC – 4oC = 70oC).
Assuming a 90% efficiency in the regeneration section, the temperature of the milk would
rise by 63oC by regeneration (i.e. 90% of 70oC). The temperature of the milk at the start
of the heating section would be 63oC + 4oC = 67oC.
Therefore, the heat required for pasteurisation would be 74oC – 67oC = 7oC.
If the regeneration section of the pasteuriser can raise the incoming milk by 63oC then it
follows that the temperature of the hot, processed milk must be reduced by the same
amount. Therefore, the temperature of the milk on exit from the regeneration section
must be 11oC (74oC – 63oC =11oC).
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The milk must be cooled by a further 5oC to comply with the recommended temperature
of 6oC for the finished product. If the process temperature is increased even slightly, the
cooling requirement increases dramatically.
Note: A 2oC rise in processing temperature increases the cooling requirements by 23%
A 3oC rise in processing temperature increases the cooling requirements by 42% !!!
The enzyme Lactoperoxidase is inactivated at 80oC. However, recent tests have shown
that the presence of Lactoperoxidase in milk may have an antibiotic effect which reduces
the number of spoilage bacteria resulting in a slightly longer shelf life. Therefore, over
processing the milk and killing the enzyme may be detrimental and actually reduce the
keeping quality of the milk.
10.4
Diagram Identifying the Relevant Parts of a Typical Small-Scale Pasteurising Unit
Key
Part Ref:
Description
a
Raw Milk In
b
Balance Tank
c
Milk Pump
d
Flow Restrictor
e
Regeneration Section
f
Heating Section
g
Holding Tube
h
Temperature Sensor
i
Flow Diversion Valve
j
Diverted Flow
k
Normal Flow
l
Pasteurised Milk Out
10.5
m
Control Panel
n
Thermograph Chart
o
Gauges
g
m
n
o
l
f
e
d
k
b
c
a
j
i
Components of a Pasteurisation Unit
10.5.1 Balance Tank and Float
Receives raw milk and ensures a constant supply of product to ensure that the
pump does not run dry.
10.5.2 Pump
Supply pump should operate at aflow rate of 2.5 – 3 times that required for
pasteurisation. This is required to ensure adequate cleaning of the plant after
each production run.
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h
10.5.3 Flow Controller/ Restrictor
This is either a valve assembly or a restrictor device in the pump. Its function is to
regulate the flow of the product through the heat exchanger during pasteurisation,
to ensure adequate heating and the correct holding time.
10.5.4 Heat Exchanger
A heat exchanger comprises a number of very thin stainless steel plates which are
batched in ‘sets’. The number of plates in a set varies and is largely governed by
the pump capacity. The larger the pump the greater number of plates in a set.
The plates are sealed from each other by gaskets.
Within the heat exchanger, cold milk for pasteurisation enters from one end and is
pre-heated by the hot milk which has been pasteurised which passes in the
oposite direction. Conversely, hot milk which has been pasteurised is cooled by
cold milk entering the unit.
As the efficiency of a heat exchanger is around 90%, additional heating of the milk
is required before it enters the holding tube. This is provided by hot water or steam
within the “hot end” of the unit.
Similarly, milk leaving the pasteuriser to be bottled/ packed will require additional
cooling. This is provided by chilled water or coolant (e.g. glycol) within the “cold
end” of the unit.
10.5.5 Holding Tube
The purpose of the holding tube is to ensure that milk which has been heated to a
temperature of not less than 72oC within the heat exchanger is held at this
temperature for a minimum of 15 seconds before it re-enters the heat exchanger
to be cooled. The dimensions of the holding tube (length and diameter) need to be
calculated in relation to the flow rate of the pastueriser. It should also have two
injection points fitted to it. One where the finished product exits the heat
exchanger and enters the holding tube and the other at the exit of the holding tube
next to the flow diversion valve, to allow an engineer to check the holding time by
measuring the length of time it takes coloured dye to pass through the tube..
10.5.6 Temperature Sensor and Gauge
The holding tube is fitted with a temperature sensor and gauge at the outlet so
that the temperature of the finished product can be measured. The sensor must
also be connected to the thermograph chart so that a permanent trace of the
temperature of pasteurisation is made.
10.5.7 Flow Diversion Valve
The purpose of the Flow Diversion Valve is to prevent milk which has not
maintained the correct temperature of (72oC) for the required time of not less than
15 seconds, from leaving the pasteuriser. It is operated by the temperature
sensor at the end of the Holding Tube. The valve should be positioned upright and
be set at high level. Diverted product must always be passed downwards and
return back to the balance tank.
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10.5.7 Control Panel
Control panel should have two ‘set points’ and one Auto/ Manual Switch.
‘Set Points’:
One set point controls the divert temperature and should
be set by the installer. This set point should be secured
(i.e. locked/ tagged/ sealed) and it must not be possible for
the operator to alter it.
The second set point controls the operating temperature of
the equipment. This controls the temperature of the water
and should be about three degrees above the process
temperature requirements. (i.e. if process temperature is
73oC operating temperature should be set at 76oC).
Auto/ Manual Switch: When milk is being pasteurised the switch must always be
set to “automatic”, so that the Flow Diversion Valve will
operate if the milk has not breached the correct minimum
temperature (72oC).
The Manual setting is required for cleaning purposes.
When the switch set to this position the Flow Diversion
Valve is disabled.
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REFERENCES
Guidance Documents
A.D.A.S.
Pasteurised milk – guidelines for “on farm” milk processors:
production steps and control means for assured hygienic quality.
(1996)
British Standards
Institute B.S.7771:
Code of practice for pasteurisation of milk on farms and in small
dairies (1994)
British Standards
Institute B.S.5305:
Code of practice for cleaning and disinfecting of plant and equipment
used in the dairying industry (1984)
Food Standards
Agency – Dairy
Hygiene Inspectorate
Milk Hygiene on the Farm – A Practical Guide for Milk Producers
(2006)
Legislation
1990 Chapter 16
The Food Safety Act 1990
SI 2004: No 2990
The Food Safety Act 1990 (Amendment) Regulations 2004
SI 2004: No 3279
The General Food Regulations 2004
SI 2006: No 14
Food Hygiene (England) Regulations 2006
EC 178/2002
- laying down the general principles and requirements of food law,
establishing the European Food Safety Authority and laying down
procedures in matters of food safety
EC 852/2004
- on the hygiene of foodstuffs
EC 853/2004
- laying down specific hygiene rules for food of animal origin
EC 854/2004
- laying down specific rules for the organisation of official controls on
products of animal origin intended for human consumption
EC 1662/2006
- amending Regulation (EC) No 853/2004 of the European
Parliament and the Council laying down specific hygiene rules for
food of animal origin
EC 1664/2006
- amending Regulation (EC) No 2074/2005 as regards implementing
measures for certain products of animal origin intended for human
consumption and repealing certain implementing measures
EC 2073/2005
- on microbiological criteria for foodstuffs
EC 2074/2005
- laying down implementing measures for certain products under
various EC Regulations [EC No. 852/2004; EC No. 853/2004; EC
No. 854/2004; EC No. 882/2004
- 33 -
Appendix A:
Pasteuriser Performance Report
Service Engineer Details:
Farm Details:
Name:
Address:
Name:
Address
Tel:
Tel:
Pasteuriser Details:
Make:
Size:
Serial No.
Processing Check
Cleaning Check
4o C
A
Raw Milk in
Test Temp.
<
B
Cold Milk
Test Temp.
< 10oC
Holding tube temp.
Thermograph temp.
Hot temp. gauge
Thermograph temp.
 0.5oC
Thermograph error
Cold temp. gauge

Cold temp. gauge error
Wash return to tank
Yes
Achieves>60oC
No
0.5oC
Mins taken to reach 60 oC
B-A
< 5o C
Difference between milk
in and milk out
+ 30 mins = cleaning time of
Is flow diversion valve cleaned?
Milk Throughput (normal flow)
Time taken to fill a
No
10 gallon Churn ( see table)
mins
60 x 10
mins taken
Yes
=
gals / hr
Are the pressures recommended by the
Yes
manufacturer maintained through Processing?
No
Milk Throughput (while homogenising)
gals / hr
Milk Throughput (take-off to separator)
gals / hr
Holding Tube
 72oC
Test temp.
Recommended Times
Thermograph temp.
Litres / hr

Thermograph error
0.5oC
Hot temp. gauge
 0.5oC
seconds
Hot temp. gauge error
Holding time
Flow Diversion

Test temp.
Flow divert
Yes
Pointer reset
No
Dye Test
110
700
3.87
155
900
3.00
200
1350
2.00
300
2000
1.35
444
Certification by Service Engineer
 0.5oC
Pasteuriser Plate Integrity Tests (when required)
Conductivity
Gals / hr
5.45
71.5oC
Setting
Pasteuriser thermometer error
Mins / 10 gals
500
I certify that I have carried out the checks
on this pasteuriser and have found it to be
pasteurising and cleaning satisfactorily
Other
Nature of Other Test
Signature
Condition of gaskets checked
Title
Date
Visual inspection of pasteuriser
Note: If more than one Pasteuriser is installed a separate Report sheet must be produced for each Pasteuriser.
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