PPECB
COLD CHAIN MANAGEMENT BY DIFFERENT ROLEPLAYERS
INDEX
3/08/2005
1.
Introduction
2.
RRMT Requirements:
2.1
2.2
2.3
2.4
Structural
Temperature
Overall Condition
Cleaning Procedure
3.
Driver Education
4.
Preparation of Refrigerated Cargo:
4.1
4.2
4.3
5.
Packaging
Pre-cooling
Selection of product
Pre-loading Checks:
5.1
5.2
5.3
5.4
Equipment
Cargo
Documentation
Temperature Requirements
6.
Loading Practices:
7.
Transport Temperature Maintenance
8.
Offloading Practices
9.
Loading Checklist
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1.0
Introduction
It is important to bear in mind that quality is the major factor that sells the
final product. Quality can be maintained only if all links in the handling and
distribution chain show equal consideration for the produce.
The transport chain therefore has the twofold responsibility of transporting
the produce and maintaining its quality during in transit by keeping produce
at set point and holding a relative humidity.
Refrigerated Road Motor Transport (RRMT) is exactly what the name implies –
a transport vehicle to move refrigerated products from one point to a
destination under cooling. This mode of transport is not a pre-cooling unit,
but designed and built to move the maximum payload at a specified
temperature.
Perishable products must therefore be pre-cooled to the transport
temperature and loaded into the refrigerated unit with a minimum increase in
product temperature.
The following paragraphs serve as a checklist of actions or questions that
have to be answered to ensure the successful movement by RRMT of
perishable products by various role-players.
2.0
Refrigerated Road Motor Transport Requirements
2.1
Structural
When buying a new refrigerated trailer ensure that it is able to maintain the
necessary specified temperature during transit. Certain features should be
noted:
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Grooved or fluted sidewalls for better air circulation around the load.
Curved air deflector at the base of the inside front wall.
Strong and tough inner wall skins to prevent mechanical damage.
Smooth outer skin and preferably white for best reflection of the
elements.
Preferable to have 50 mm deep T-Bar grooved floors to allow for
better air circulation.
The following minimum thickness of insulation must be adhered to –
Sidewalls
Roof Panels
Floors
Bulkhead
Doors
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between
between
between
between
between
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55 to 65 mm
70 to 100 mm
100 to 115 mm
70 to 100 mm
70 to 100 mm
2.2
Temperature Requirements
A refrigerated truck system must have sufficient capacity to remove heat
generated by the following sources:
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Residual heat from the air inside the trailer –
In order to overcome this it is recommended to have trailers precooled prior loading and to practice fast loading.
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Environmental heat from outside through small holes or cracks as well
as ambient heat soaked off the road through the floor –
Body and door seals should always be kept in a perfect condition.
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Heat of Respiration generated by produce –
The higher the product temperature, the faster the respiration rate,
therefore products should be loaded at the required temperature.
The following features should be noted when purchasing a new vehicle in
order to meet strict temperature requirements:
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2.3
Refrigeration unit with a fan capable of circulating at least 0,944 m/s
of air against a 50 mm water gauge static pressure.
A large evaporator coil to maintain constant temperature.
A solid state temperature controller (Thermistor)
A thermostat that has a change over switch for delivery and return air
control.
Thermograph or temperature recorder to supply continuous
temperature history.
Thermocouples in the delivery and return air streams for temperature
checking and calibration of the thermostat.
Rigid ducting to facilitate even distribution of cooled air throughout the
trailer.
Overall Condition
The condition of a trailer affects its capability to maintain the temperature of
products as much as its design. It is therefore recommended for all vehicle
owners or operators to pay attention to the following aspects:
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Damaged wall and floor insulation – allows excessive heat to be
conducted from outside into the trailer.
Wet insulation due to cracks – will eventually deteriorate and looses its
effectiveness as an insulator.
Broken places or cracks in the wall and floor – may house dirt and
pathogenic microorganisms and are difficult to clean.
Faulty doors and deteriorated or cracked door seals – won’t be able to
maintain proper temperature control and will allow dust to enter the
trailer.
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2.4
Not properly fitted and sealed steel plates – may damage loads or
allow for fungal growth or insect breeding behind the plates.
Blocked and dirty cooling coil plenums and return air ducts – will not
be very effective during cooling.
Dirty trailers – may contaminate produce due to certain odour build up
within the vehicle.
External cleanliness of trailer – Dirty bodywork absorbs more heat
than clean, white bodywork. Dirty trucks on the outside – won’t be
able to reflect any heat.
Inaccurate and non – calibrated control systems – won’t be able to
ensure correct product temperatures.
Wrong positioning of the thermostat sensor – will cause severe cold or
freezing injury to perishable products.
Unroadworthy vehicles according to the National Road Traffic Act –
may cause unnecessary delays if stopped by traffic officials.
Cleaning Procedure
General
The cleaning methods and inspection criteria presented in this document are
intended to provide end users with a properly cleaned vehicle. Strict
international rules and regulations apply to the handling of perishable
produce. These regulations also apply to all transporting modes carrying
perishable products for exports from South Africa.
Cleaning Procedure
When cleaning is required? An additional objective is to eliminate
unnecessary cleaning costs by replacing more costly methods such as
washing with less costly methods, such as sweeping.
As a general guide, cleaning is required when material is present that is both
transferable to cargo and that is visibly dirty, sticky or wet and that cannot be
easily removed by brushing or dusting off without leaving stains.
In order to determine when to clean, the following general guideline should
be followed –
Cleaning is required when the following conditions are present:
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If the material is transferable to cargo;
Residue or odour is detected;
General appearance and cleanliness that would not be acceptable to
end-user.
The method used should be the least destructive, least complex and most
economical cleaning method, which is effective, but does not negatively affect
any part of the vehicle.
The following cleaning recommendations can be used as a guideline:
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Sweep OutDust, dirt and small remnants of previous cargo, should be swept out
of the Vehicle.
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Spot CleaningSpot cleaning is applied when only small areas need to be cleaned by
way of using a cloth and absorbing liquid.
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WashingWash with cold water with or without detergent in trailers if light
stains, fine dust and other materials remain after sweeping method.
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Cold High-Pressure Wash
To be used if stains, fine dust or other materials cannot be cleaned or
removed by any of the methods listed above.
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Hot High-Pressure Wash
Is the most effective way to clean oil stains. It is also the standard
way to clean refrigerated interiors and to remove odours from
vehicles.
Chemicals to be used
A detergent, free from perfume and other odoriferous materials
approved for cleaning surfaces and areas in direct contact with food,
can be used to facilitate cleaning and/or to remove any possible taint.
3.0
Driver Education
The driver should be adequately trained in transportation of refrigerated
products and be able to do the following:
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Supervise the loading process to ensure that no cargo or vehicle be
damaged during the process.
Ensure that cargo is loaded in such a way as to maximize air flow
within the trailer.
Insist on the removal of damaged packaging and products.
Ensure that cargo in partly load vehicles is properly secured.
Ensure that temperature checks are performed and documented.
See to it that all faults or damaged panels are repaired as soon as
possible.
Ensure that vehicles are delivered in a clean state at the loading
point.
Ensure that the cooling unit is functioning correctly. See to it that
trailers are pre-cooled and set at the correct temperature setting prior
loading.
Make scheduled checks to make sure that the refrigeration unit is
functioning correctly whilst refrigerated cargo is being transported.
Apply the same supervision during the off loading process.
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Ensure that proper loading and off loading checks and temperatures
are captured and signed for it by the driver and cold store operator.
Carry out the necessary loading and off-loading checks.
Ensure that product temperatures are correctly recorded, and then
sign the temperature recording form (PPECB Q02 Form).
Ensure the space behind the return air wall is free of any packaging
material, which will impede airflow.
4.0
Preparation of Refrigerated Cargo
4.1
Packaging
It is recommended for carton manufactures to take note of the following
aspects:
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4.2
The quality of the carton tends to depend on the value of the product
and on the length of the journey. Carton quality should be such that it
adequately protects the product from the packhouse to the point
where its unpacked.
Cartons must have sufficient strength to withstand continuous load
movement during transportation, and should not absorb moisture that
may cause them to soften and collapse.
Package design also pays an important part in transferring heat,
therefore packaging must allow for inadequate and unobstructed
airflow in both vertical and horizontal planes.
Carton ventilation must also align with pallet base openings through
the total load to facilitate vertical movement of air.
All pallet loads must be stabilized and properly strapped onto an
unbroken pallet base.
Never mix different packaging in the same load because it will result in
serious air circulation differences which compromise airflow and the
ability to remove vital heat.
Pre-cooling
The following aspects are of importance and Cold Store Operators must take
note of the following:
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To maintain a fresh appearance, prevent decay and extend
shelf life, it is necessary to start lowering the temperature and
remove the field heat from the product as soon as possible
after harvest.
A refrigerated vehicle can only maintain product temperature.
The product must therefore be pre-cooled to the required or
specified export temperature.
Proper and uniform pre-cooling is also an important
prerequisite for good temperature control within a refrigerated
vehicle.
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4.3
Loading cargo without proper pre-cooling cause’s condensation
problems. These could include restricted airflow due to ice on
the evaporator coil, or damp and weekend packaging.
Selection of Product
Prior loading, it is important for the loading point to take note of the
following:
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5.0
Ideally the export consignment must be made up according to the
buyer’s specification before loading of refrigerated vehicles.
This process must be done in the cold store to maintain optimum
product temperature.
Sorting and selecting during loading will delay the process and will
cause and increase in temperature.
Pre-Loading Checks
Every load and vehicle must be checked before loading according to:
5.1
Equipment
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5.2
Cargo
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5.3
Carriers should check their equipment before presenting it to the
shipper. This procedure is commonly known as the Pre-Trip Inspection
or PTI, whereby the machinery is subjected to a functional test.
Vehicle Operators/owners should ensure that the refrigeration unit is
set correctly for the load and is functioning properly and controlling the
temperature at the required level.
All trailers should be pre-cooled prior loading, with the unit switched of
at time of loading. If the trailer has a solid airflow ducting, it is not
necessary to turn off the refrigeration unit due to vertical air delivery.
Cold stores must make sure that all products are inspected and
approved prior ordering a vehicle.
Products should be clearly marked and identified as per importing
countries’ requirements.
Documentation
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Drivers must ensure that proper documentation and clear instructions
are issued before departing from loading point.
Packhouses should ensure that the necessary export certificates are
issued prior loading.
The RRMT operator should make use of the temperature analysis form,
(Q02) which must be signed for by the driver and packhouse operator.
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5.4
Temperature Requirements
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6.0
Recording equipment used, should fit the task at hand and must be
calibrated periodically.
Product temperature must be taken at the time of loading.
The following information, that also forms part of traceability
requirements should be recorded:
Pallet identification number and
Fruit temperature in centre of pallet and
Fruit temperature of the inner fruit in a carton on the outside
Of the pallet and
Capture all readings and countersigned by driver.
All temperature applications must be applied within industry protocol
and procedures. All temperature measurements must be carried out
according to industry protocol and procedures.
Loading Practices
The loading of refrigerated cargo must be as quick as possible to minimize
temperature increases. The following are important requirements:
6.1
Vehicle Requirements
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6.2
The cargo space shall be clean.
There must be no traces of odour from previous shipments
All spaces shall be dry and free from fungal growth.
All interior and exterior panels, doors and seals must not be damaged
in any way.
Loading Process
The two most important factors to take into consideration during the loading
process are time and contact with ambient air. Ideally the loading should
take place from an enclosed pre-cooled loading bay area. (Airlock)
There are a number of ways to contribute to proper loading, some of which
are as follows:
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Make sure that the product loaded first is not pushed up hard against
the evaporator.
Load the product on pallets away from the sidewalls.
Total pallet load should not be higher than 2.1 m and leave at least
150 mm between load and ceiling.
Allow at least 80 mm space between the door and the last pallet.
Pallets should be loaded in such a way that ventilation holes on the
sides of cartons face from the front of the trailer to the back, allowing
for lateral air flow from the door end, back to the refrigeration unit.
Stow the commodity uniformly in accordance with shipper’s
instruction.
With top air delivery using canvas ducts, avoid distorting the ducts.
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6.3
Do not leave large spaces in the center of the load.
Do not run the refrigeration unit during loading, except for those
trailers fitted with solid ducting systems.
If loading is interrupted, close doors and run refrigeration unit.
Cartons and pallets must be stowed in such way that they allow for
unobstructed vertical airflow channels.
Loading must be completed within 30 minutes.
Specified axle load limits must be adhered to.
Stabilizer bars must be used in all loads to prevent pallet movement
and mechanical damage to pallets.
Mixed Loads
Mixed loads should not be shipped unless the commodities are compatible.
Five important factors should be considered in determining the compatibility
of products:
• The required transit temperature;
• Required relative humidity;
• Emission of physiologically active gasses such as ethylene;
• Odour absorbing characteristics;
• Type of packaging.
7.0
Transport Temperature Maintenance
The driver of a vehicle must:
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8.0
Check that the refrigerated unit runs continuously during transit.
Check on thermostat settings, indicated temperature readings, any
alarm lamps and defrost operation.
Ensure that the temperature control thermostat is set to deliver at the
specified temperature.
Ensure that the hour meter reading of the refrigeration unit is
recorded, and to indicate the time of reading, prior leaving the loading
point.
Communicate all malfunctioning of equipment, deviations and delays
to vehicle owner.
Ensure that there is sufficient diesel, to power the cooling unit.
Off Loading Practices
The driver should perform the following functions:
• Keep the refrigeration unit running until the doors are about to be
opened.
• Record the hour meter reading when the refrigeration unit is switched
off and to indicate the time of reading.
• Supervise the off loading process.
• Report all problem arrivals e.g. warm temperatures, damaged cargo
or any problems to vehicle, to the owner.
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Ensure that the reason for not accepting the consignment be stated on
the delivery note, should the consignment not be accepted.
Ensure that all temperatures i.e. air delivery, return and chart readings
are documented and singed for by intake point.
All pre-shipment history will be complied from the above data, should any
problem arise or claim be filed, due to loss of quality.
R Robinson
PPECB
PM CCS
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RRMT LOADING CHECKLIST:
To be used before and during loading process.
Inspect Vehicle:
PPECB Certified
Cleanliness
Taint Free
Structural Damage
Doors close properly
Sufficient diesel to power unit
Temperature Setting:
Correct Setting
Pre-Cooled Vehicle
Clear Destination
Completed Q02 Form
Correct Load
PPECB Inspected
Per Specified Temperature
Properly Palletized
Record Readings
Within Spec
Documentation:
Cargo:
Temperature Checks:
Loading Process:
Away from sidewalls
No Damages
Enough space between Roof/Doors
Stabilized bars used (Part Loads)
Doors are properly closed and sealed