Ships’ holds for the transport of perishable products must be absolutely clean, free from any taint, and protected from pollution such as oil, bunker fumes, and exhaust gases. Reliable and accurate temperature maintenance, air handling systems, and a recording/logging system are basic requirements for carrying perishable products. Some of the more important PPECB requirements are briefly discussed in this chapter.
1. Precooling of Decks
All decks to be used for carrying South African perishable produce must be thoroughly cleaned and then precooled prior to a PPECB inspection.
1.1 PPECB Requirements
All decks to be used for the carriage of South African perishable produce must be precooled for at least 48 hours, and the following return air temperatures (RAT) must be maintained for at least 24 hours prior to commencement of loading:
- Chilled produce: Precool to -0.5°C ± 0.5°C.
- Chilled produce for in-transit cold treatment: All decks must be precooled for at least 48 hours, and all cargo and air sensors must record a constant temperature of -0.5°C for at least the last 24 hours prior to loading.
- Deep frozen produce: Precool to -18°C or colder.
The temperature control thermostat can be set slightly colder (e.g., -1.0°C for chilled and -20°C for frozen cargo) to maintain the specified RATs. The precooling process, including defrost cycles, must be accurately logged or recorded for scrutiny by the PPECB.
1.2 Agent’s Instructions
The ship’s agent is the local contact for vessels carrying South African perishable produce. All PPECB communication with vessels at sea, during loading, and after discharge will be via the local ship’s agent unless otherwise arranged. The ship’s agent must:
- Inform the Master of the vessel of the PPECB precooling, technical, and deadline requirements.
- Supply the PPECB with a valid copy of the USDA certificate for the vessel if used for carriage of fresh produce to the USA or for in-transit cold treatments to other destinations.
- Inform the Master of the PPECB requirements regarding temperature management and voyage temperature logs.
1.3 Records Required from the Master
It is strongly recommended that the Master arranges for the following actions and documents to assist the PPECB during the preloading inspection process:
- Calibration certificates for all temperature and carbon dioxide (CO₂) instruments.
- Calibration data on the precalibration done by the crew in preparation for in-transit cold treatment.
- Logs of the previous shipment to confirm that carrying conditions can be maintained.
- Records of cargo carried on previous voyages to assess any taint and product contamination risks.
- Records on maintenance and repairs of refrigeration equipment, temperature controlling, and recording systems.
- Records on cleaning and deodorisation of decks and maintenance of floor gratings and cargo handling equipment.
2. Preparation of Vessel
All shipping spaces must comply with national and international requirements to minimize product quality losses and guarantee food safety and traceability. PPECB is responsible for ensuring that perishable cargo is handled and shipped under optimum conditions.
2.1 Structural Maintenance
The vessel must comply with internationally accepted maritime requirements for seaworthiness and other legal requirements. Important conditions include:
- Hatch covers must open and close freely and seal properly to minimize heat leakage.
- All cargo handling gear must be in good working condition for fast and uninterrupted loading, handling, and discharge.
- All floor gratings and cargo securing structures must be in good repair for efficient loading, stability, and discharge.
- All air ducts, water draining pipes, and systems must be clean and provide efficient, unobstructed flow.
- All insulation must be intact, well secured, and dry. Damaged insulation must be replaced with clean, new insulation of the correct specification.
- All container handling and securing devices for on-deck containers, as well as power supplies, must be in good, safe, and working condition.
- All materials used, maintenance methods, and procedures, as well as personnel training and competency, must comply with international specifications (e.g., Lloyds or similar bodies).
2.2 Cleanliness Requirements
All spaces to be used for perishable products must be absolutely clean. The three basic food safety requirements—physical, biological, and chemical cleanliness—must be checked by PPECB. Of particular importance:
- All gratings must be free from any foreign matter and clean.
- All floor surfaces underneath the gratings, especially joints in the floor structure, must be clean and rust-free.
- All side walls, ceilings, and deck covers must be clean, free from fungal growth, dry, and smooth to minimize dust accumulation.
- All air ducting must be clean inside and outside.
- All drain pipes must be clean to ensure efficient drainage and eliminate pollution.
- All air circulation fans and fan housings must be absolutely clean; no deposits on fan blades, housings, or protective screens.
Clean, unpolluted water must be used to wash cargo spaces. Only approved and registered detergents and cleaning materials may be used. Any trace of fungal growth must be treated with an approved fungicide at the correct concentration.
2.3 Deodorization of Shipping Spaces
All decks for perishable products must be taint-free prior to loading and kept free from contamination and pollution during loading and the voyage. Most taints are from materials used (paints, silicone sealants, detergents) or from previous cargo (onions, garlic, fish, chemicals). Important aspects:
- Only approved and registered paints, sealants, cleaning products, etc., must be used as per manufacturer recommendations.
- Special care must be taken when carrying cargo that may taint the shipping space (e.g., chemicals, onions, hides).
- All remnants of cargo, especially after carrying loose fish, must be removed immediately after discharge.
- The origin and nature of the taint will dictate the deodorization method. Guidelines include:
- Thorough cleaning followed by adequate fresh air ventilation immediately after discharge.
- If any odor is detected after normal cleaning, a 6% Hydrogen Peroxide (H₂O₂) solution can be used to wash down the contaminated area.
- Activated charcoal (1kg/100m³ space) can be used while ventilating with fans at half speed. Note: charcoal only removes odor from the atmosphere, not the source.
2.4 Cooling System Maintenance
Routine maintenance must be done according to the manufacturer’s instructions. Only approved materials, spares, and procedures must be used by experienced and trained personnel. Ensure:
- Detailed records of all maintenance and repairs are kept.
- Routine inspections and tests are performed and documented as per manufacturer recommendations.
- The general appearance, functioning, and records of previous voyages must create confidence that the cooling system is reliable and will perform within tolerances during the next voyage.
2.5 Calibration of Temperature Control Systems
Temperature control thermostats or electronic controlling devices should be calibrated. The temperature in all refrigerated spaces must be controlled at the specified product temperature with a maximum deviation of ±0.5°C. Measuring and recording the temperature of the delivery air approximately three meters from the cooling coils indirectly checks the temperature controller.
- The calibration test should include at least one defrost cycle to ensure the controller restarts correctly.
- The controller should be checked for linearity at a warmer (e.g., +5.0°C) or colder (e.g., -18°C) temperature if subtropical fruits or deep frozen produce are to be carried.
2.6 Calibration of Temperature Recording Systems
The Master of the vessel is responsible for ensuring all controlling, measuring, and recording devices are calibrated. PPECB will check these calibrations and may require a calibration certificate from an accredited organization. Quarantine regulations for in-transit cold treatments or certain exporters/importers may require PPECB to perform extensive calibration on all temperature measuring and controlling devices.
2.7 Maintenance of Temperature Logging Systems
All temperature controlling, measuring, and logging equipment must be well maintained to ensure accurate and reliable functioning during the voyage. Quarantine Authorities may require a guarantee that the temperature equipment functions accurately for at least one month after departure. It is essential that:
- Personnel are well-trained and experienced for routine equipment maintenance and minor repairs.
- Only spares and procedures specified by the manufacturer are used.
- A competent and qualified representative of the manufacturer is available for major repairs if required.
- The Master must ensure necessary maintenance procedures are carried out and inform the local ship’s agent well in advance of any spares or specialized repairs needed.
PPECB will not authorize commencement of loading unless convinced that the temperature controlling, measurement, and recording systems are operating within the relevant specification.
3. Vessels for In-Transit Cold Treatment
Certain countries require in-transit cold treatments to eradicate specific insects. These requirements are strict; non-conformance may result in the product being returned or diverted. Bilateral agreements between the South African Department of Agriculture and the importing country govern export conditions and treatments. PPECB ensures compliance.
3.1 Verification of Cold Treatment Certificate
All vessels used for in-transit cold treatment must have a valid cold treatment certificate. Two bodies issue certificates for the South African trade:
- USDA certificate: Issued by an accredited United States Department of Agriculture official. Valid for three years, renewable after re-inspection. PPECB may issue a temporary certificate under special conditions, endorsed by the USDA.
- PPECB certificate: Issued by an accredited PPECB official after a detailed inspection. Criteria are similar to USDA, but some countries require a guarantee that all temperature devices hold calibration for at least one month. Some require an “empty deck” test under PPECB supervision.
3.2 Cargo and Space Temperature Sensors
Sensors measure cargo (fruit or pulp) and air temperature in different deck positions. Requirements:
- Independent decks: Minimum 3 fruit and 2 air temperature sensors for smaller decks; 4 fruit and 3 air sensors for larger decks.
- Twin compartment decks: Minimum 3 fruit and 2 air temperature sensors per deck.
Connecting cables must be at least 5 meters long. Handle sensors carefully as they are delicate and can be damaged or develop loose connections.
3.3 Maintenance and Precalibration of Temperature Data Logging System
Quarantine requirements for in-transit cold treatments are strict. Any malfunctioning of the temperature system will result in shipment rejection. Vessels must:
- Have all relevant service manuals.
- Employ well-trained technicians for routine maintenance at sea.
- Carry necessary spares of the correct specification.
- Perform routine maintenance as specified.
- Have an agreement with a competent service provider in South Africa for advanced repairs.
Temperature recording/logging equipment must maintain calibration for at least one month. All temperature data must be stored for at least one month to ensure all records are available as one set of data, printout, or graph. Precalibration by the crew before arrival in a South African port is strongly recommended.
General guidelines:
- Set thermostatic temperature controllers to deliver air at -0.5°C ± 0.5°C.
- Ensure unobstructed airflow across cooling coils into the air supply plenum.
- Ensure fixed air sensors are properly mounted and protected from heat sources.
- Ensure all cable connections are intact and protected.
- Ensure connecting cables are of required length and stored for easy placement.
- Ensure all cabling is protected, undamaged, neatly fixed, and identified.
- Ensure temperature data loggers/recorders are properly maintained and commissioned for the next voyage.
Proceed with the calibration procedure as outlined in section 3.5. Submit precalibration records to PPECB prior to official calibration.
3.4 Precooling of the Holds
All decks to be used for South African perishable products must be precooled to -0.5°C for at least 48 hours and maintained at a constant temperature of -0.5°C for at least the last 24 hours prior to loading. For in-transit cold treatment, all cargo and air sensors must record a constant temperature of -0.5°C for at least the last 24 hours.
3.5 Temperature Checks and Calibration
General procedures followed by PPECB for temperature checks and calibration:
- Check temperature records of previous voyages and precalibration by ship’s personnel.
- Check the general condition of temperature controlling, measuring, and recording equipment.
- Check records of routine maintenance.
- Install new charts in loggers and set recording/printing interval at 60 minutes.
- Switch off precooling.
- Prepare ice cubes (approx. 2x2x2 cm) from pure distilled water.
- Fill insulated ice buckets with clean ice cubes; add a small amount of distilled water. Stir slowly and continuously.
- The ice-water mixture must register 0.0°C on a certified calibrated thermometer.
- Submerge temperature sensors in the ice-water mixture, keep stirring, and ensure the thermometer registers 0.0°C.
- Print out the temperatures recorded during calibration.
- Make a second printout.
- Sensors must register within 0.0°C ± 0.2°C, and the maximum difference between any two sensors may not exceed ±0.1°C.
- If parameters are not met, make a third printout; if still not met, service the total system.
Japanese Plant Quarantine Authorities also require a 24-hour empty deck test under their supervision, done after PPECB calibration.
3.6 Approval of Vessels for Cold Treatment
- The USA only acknowledges certificates issued by the USDA (valid for three years, but may be terminated sooner if criteria are not met).
- PPECB can, by arrangement with USDA, issue an extension certificate, endorsed by USDA calibration on arrival in the US.
- Some countries acknowledge the USDA certificate; others (e.g., Japan) require a PPECB calibration certificate regardless of USDA certification.
- The PPECB certificate is valid for three years but will be cancelled if the vessel fails to execute a cold treatment procedure successfully.
- A complete list of vessels certified for cold treatment of South African perishable products is available from PPECB.
4. Vessels for Carrying Conventional CA Cargo
Controlled atmosphere (CA) and modified atmosphere (MA) storage and transport require reduced oxygen (O₂) and increased carbon dioxide (CO₂) in the atmosphere. Special care is needed to ensure correct gas concentrations and personnel safety.
- CA decks are completely gas-tight, including deck and hatch covers.
- Gases are measured and controlled by introducing nitrogen (N₂) to reduce excess oxygen and by scrubbing excess carbon dioxide.
- Oxygen is introduced by controlled venting with outside air to replace oxygen used by respiring fresh product.
- MA is usually applied on a carton or pallet basis, using sealed bags of specially formulated polyethylene laminations. No special equipment is needed for MA produce, but it is very temperature dependent.
4.1 CA Decks
The shipping line must have procedures for gas tightness, methods to check for tightness, and procedures to maintain and restore gas tightness. Key aspects:
- Regular maintenance of deck structures (e.g., joints in insulation and gas seal, seals on pipes/cables/ducting).
- Gas-tight sealing of deck and hatch covers as per shipping line specifications.
- A gas equalizing system must be installed and fully operational to ensure equal atmosphere pressures inside and outside the gas barrier.
Instruments Required
- Gas measuring and recording instruments connected via manifolds and gas-tight piping to different positions in the deck.
- Instruments measure, control, and record oxygen and carbon dioxide.
- Some decks may have ethylene analysers to control ethylene for certain fruits, vegetables, and flowers.
4.2 Calibration of Gas Analysers
- Ensure absolute gas-tight sampling lines to the different CA decks.
- All gas analysers must be checked daily and calibrated as per manufacturer specifications.
- Calibration records must be kept for future reference.
5. Vessels Carrying Ventilated Cargo
PPECB does not recommend the carriage of perishable products under ventilated conditions. Some produce (e.g., onions, dried fruit, canned produce) may keep well for short periods at ambient temperatures. Condensation is always possible and usually causes product quality losses and packaging damage. PPECB strongly recommends a constant temperature (usually 16°C) for produce that keeps well at ambient temperatures, resulting in constant relative humidity (RH) and reducing condensation risk.
5.1 Air Handling Requirements
Heat of respiration and transpiration moisture from the cargo must be continuously removed. In unrefrigerated below-deck spaces, this is done by efficiently moving large volumes of fresh air through the cargo.
5.1.1 Fresh Air Ventilation
- Must be applied to maintain CO₂ concentration below 0.5% at all times.
- Minimum of 12 complete fresh air changes (based on empty volume) per 24 hours is required.
- Exhaust fans must remove 1200 m³ of air for every 100 m³ of shipping space per 24 hours.
- Fresh air ventilators must be fully open during the voyage; continuous ventilation must be applied as long as intake air temperature is equal to or less than exhaust air temperature.
- When inlet air temperature exceeds exhaust air temperature, continuous ventilation must stop. Fans must operate at least 2 hours during the coldest period per 24 hours while ambient air exceeds under-deck air temperature.
- Fresh air intake must stop when ambient air drops below 5°C. Ensure CO₂ levels do not exceed 0.5%; if they do, introduce only enough fresh air to maintain CO₂ below 0.5%.
5.1.2 Air Circulation
- Air circulation in the deck must be at least 90, preferably 120, complete air changes per hour (based on empty deck volume).
- Cargo must be packed in well-ventilated containers (e.g., woven/knitted jute or polypropylene bags, or cartons with sufficient ventilated openings facing airflow direction).
- Correct stowage is important to ensure circulating air is forced through the load.
- No open spaces between pallets; forklift entries in pallet bases must face airflow direction.
- Openings on wings and flares must be blocked with air bags or suitable material.
5.2 Instruments Required
Ventilated spaces must be equipped with accurate temperature recorders to record air temperatures in at least three positions:
- Fresh air inlet ventilator
- Exhaust air ventilator
- Expected warmest position in the deck
The CO₂ concentration in the expected area of highest concentration (normally at floor level furthest from air circulation fans and fresh air inlet) must be continuously recorded. Temperature and CO₂ readings and records must be kept and made available on request to PPECB.
5.3 Food Safety Requirements
Basic food safety requirements are highlighted in Chapter 1, paragraph 3.1. This is particularly important for loading, carrying, and discharge of ventilated cargo to prevent contamination and taints.
- Contamination of cargo must be avoided at all times. Only perishable cargo should be loaded into decks; never mix food products with cargo containing chemicals or packed in glass (e.g., cement, fertilizers, wine, or canned food in glass containers).
- Tainting of cargo is a high risk in ventilated cargo. Only pure, clean fresh air from the atmosphere should be introduced. Fumes from bunkers, diesel, and exhaust gases must never enter compartments containing perishable products.
Taints can also come from other perishable cargoes such as onions, dried fish, and spices. See Chapter 8 for more detail.