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Requirement of controlled atmosphere in a reefer chamber - How to keep cargo fresh ?

Control of ventilation level

The importance of ventilation should not be underestimated. Proper ventilation of fresh, chilled products is necessary to remove the heat, carbon dioxide and other gases produced by the cargo. Heat is removed by continuously circulating the internal air, whereas carbon dioxide and other gases are removed by replacing the internal air supply with cooled fresh air.

Control of relative humidity level

Controlling the relative humidity level is also important when it comes to controlling the quality of chilled products. The relative humidity level affects many products, particularly the shelf life of fruits and vegetables – and thus their condition upon arrival.

If the humidity is too high, mould and/or fungi may develop. If the humidity is too low, it may result in a higher weight loss causing products to wilt and/or shrivel. For many products, it is therefore important to be able to control the relative humidity level during transport.

Please note that two different systems are used to either decrease or increase the relative humidity level, depending on the commodities involved.

How to control the atmosphere in a reefer container ?

Atmosphere control is another crucial variable in securing the quality of chilled cargo. When fresh perishables are shipped to distant markets, they require a precisely controlled transport environment. It is well known that harvested fruits and vegetables continue to live and breathe until they are consumed or destroyed by decay or desiccation. Under normal circumstances, these factors dictate the life span of individual products.

The life span can, however, be prolonged by keeping the commodities at their optimal temperature, combined with the supply of the most effective blend of oxygen, carbon dioxide and nitrogen.

By transporting products under Controlled Atmosphere, the applied environment will slow down the ripening process and extend the shelf life of the products. For further details please refer to the Equipment section of this brochure.

Reefer container configuration
Fig: Reefer container inside

Cold treatment

The purpose of Cold Treatment is to exterminate insects and larvae by maintaining a sufficiently low temperature for a pre-determined period of time. The period of time and temperature required are defined in protocols established by phythosanitary authorities of the importing countries. If the temperature rises above the established requirements, the entire Cold Treatment process will fail and must either be extended or started over again depending on the protocol. Applying Cold Treatment eliminates the need to fumigate cargo using insecticides, such as methyl bromide, which is illegal in many countries.

Cold Treatment is primarily applied to various types of citrus fruits, such as oranges, grapefruit and clementines. However, kiwi fruit, apples, pears, grapes, lychees, loquats, etc. can also be carried under Cold Treatment.

In order to reap the maximum benefits from the Cold Treatment process, several factors are absolutely essential. These factors include the correct pre-treatment, proper pre-cooling of the products, optimal packaging and stowage, as well as the constant monitoring at the terminals and on board the vessels.

Other useful articles :
  1. Methods of refrigeration

  2. Refrigeration is essentially the removal of heat through the process of evaporation. We choose to refrigerate commodities such as fruits and vegetables because we want to prolong their “practical shelf life” – the time from harvest until the product loses its commercial value.
    More .....

  3. Reefer cargo stuffing

  4. it is essential that all products are treated correctly prior to stuffing. Even though the temperature, ventilation and humidity are all optimal during the entire voyage, products will only arrive in perfect condition if the pre-treatment has been performed correctly. Successful shipping begins at the product sourcing area.
    More .....

  5. Growing demand for container refrigeration

  6. On deck refrigerated containers are generally serviced by clip-on air cooled electric motor drive cooling units. The units are plugged into the ships electrical system by way of suitable deck sockets.
    More .....

  7. Frozen products packaging requirement

  8. Proper packaging procedures will help protect frozen cargo during transport. Frozen products do not require air holes in the top and bottom of the cartons. Air flowing around the load is sufficient to remove heat that has penetrated the container. The cartons should be stacked directly on top of each other to take advantage of their strength in the corners.
    More .....

  9. Packaging & stowage guideline for reefer cargo

  10. Packaging plays an important role when it comes to protecting the cargo. The packaging material must be able to support a stacking height of up to 2.4 metres (7’10’’). The material should be able to withstand humidity without collapsing, and should allow the passage of an adequate vertical airflow through the cartons in order to maintain the desired temperature..
    More .....

  11. Choice of packaging for various commodities

  12. Goods should be well stowed within the package, evenly distributed and properly secured. Items completely filling the case or carton contribute to the strength of the whole package. Items which do not completely fill the package must be cushioned against shock or vibration.
    More .....

  13. How to keep cargo fresh ?

  14. Proper ventilation of fresh, chilled products is necessary to remove the heat, carbon dioxide and other gases produced by the cargo. Heat is removed by continuously circulating the internal air, whereas carbon dioxide and other gases are removed by replacing the internal air supply with cooled fresh air..
    More .....

  15. Loading precautions for refrigerated cargoes

  16. Refrigerated cargoes include meat carcases, carton (packed) meat, fruit, cheese, butter, fish and offal. Ships are specifically designed for their carriage, with separate spaces in holds and ’tween decks, each fitted with suitable insulation and individual control of ventilation. Ordinary general cargoes may be carried in the spaces at other times, the temperature being regulated accordingly for the type of cargo being carried.
    More .....

  17. Role classification societies maintaining seaworthiness of vessels

  18. classification societies publish rules and regulations which are principally concerned with the strength of the ship, the provision of adequate equipment, and the reliability of the machinery .
    More .....

  19. Periodic survey requirement by classification societies

  20. To maintain the assigned class all steel ships are required to be surveyed and examined by the Society’s surveyors at regular periods. The major hull items to be examined at these surveys only are discussed here..
    More .....

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