Our reefer containers enable adjustment of the fresh air ventilation level for the purpose of diluting or removing undesirable gases (for example, ethylene and CO2) generated by the cargo inside the container during the transportation period. This can reduce or eliminate negative effects such as the acceleration of the ripening process or flavor loss of some commodities. The necessity and quantity of air exchange depends on commodity type and condition at the time of loading.
Temperature control is the most critical function of any reefer services. Temperature has the largest effect on the respiration of produce and bacterial growth. A temperature increase of 10°C will result in an approximate doubling of the respiration rate of fruit; while lowering the temperature will substantially reduce the growth rate of micro-organisms. However, an optimal temperature set point, which is commodity-specific, is needed as too low a temperature may also cause adverse effects like chill injury of fruits, meat texture changes, or crystallization of some chemical products.
It should be noted that reefer equipment is designed to regulate temperature inside the container in relation to the cargo pre-loading condition, rather than removing heat absorbed by cargo before or during its loading. Hence, proper pre-treatment and pre-cooling of cargo, as well as proper handling in the appropriate ambient conditions during container loading and unloading, are crucial to maintain cargoes in the best possible condition.
Reefer cargoes are generally classified according to the storage temperature as below:
The optimal temperature set-point is commodity-specific.
The reefer machine unit features a dehumidifier to lower the humidity level inside the container. Typical usage includes the transportation of flower bulbs and precision instruments. The humidity level can be reduced to a set percentage during voyage to provide the desirable environment for the cargo. The correct setting also serves the purpose of complying with some import regulatory requirements, for example, acquiring the ATO-DLO certification from the Netherlands Agricultural Ministry for the transportation of flower bulbs.
Atmosphere control is the process by which the internal gas atmosphere of the reefer container is changed, regulated or enhanced in order to reduce the decay and ripening of fresh produce. Food quality is better maintained, enabling a longer transit time, wider geographical distribution, and extended shelf life.
Perishables, especially climacteric fruits and vegetables, continue to live and breathe after harvesting and during transportation to the consumer. Various technical development and techniques have been developed to slow down the rate of respiration and extend the shelf-life of perishables, including storage atmosphere control and treatment of foodstuffs prior to and during transportation. Normal air mainly comprises 21% oxygen (O2), 0.038% carbon dioxide (CO2) and 78% nitrogen (N2). During respiration, fruits and vegetables take in oxygen and emit carbon dioxide and ethylene. By altering the composition of oxygen and carbon dioxide in the atmosphere, the respiration rate of perishable products can be slowed down and the storage life is extended. Below are several atmosphere control technologies commonly employed in today’s reefer transportation:
Modified Atmosphere (MA) refers to the technology which changes the composition or concentration of gases inside the reefer container. Typically, nitrogen is injected in the container from an external source during cargo loading to replace oxygen. With a low oxygen atmosphere, respiration and ethylene production of fruit and vegetables are significantly reduced, which in turn slows down ripening and decay.
Controlled Atmosphere (CA) refers to the technology which actively regulates a modified atmosphere composition. The initial composition of gases is maintained for the duration of storage/transit by the addition or removal of undesirable gases controlled by a regulating device installed on the reefer container.
Ozone Enhanced Atmosphere is the active introduction of ozone into the internal atmosphere of the container, which has the effect of preserving the cargo. Regulated amounts of ozone are released into the reefer container throughout its journey, which reduces microbial decay and slows ripening for commodities such as climacteric fruit and vegetables by decomposing the ethylene they generate.
Selection and application of the atmosphere control technology is commodity-specific. MOL works closely with a number of atmosphere control technology providers in the market, (for example, Transfresh, MAXtend, Purfresh), enabling the company to offer customers a range of transportation solutions, whatever their requirements are. For specific information, please contact your local MOL office or email email@example.com.
Cold treatment (or sometimes called cold sterilization) is a common practice in containerized reefer services. In cold treatment, an uninterrupted and sufficiently low temperature is maintained for a predetermined duration in order to kill any insects and larvae that may be hidden in perishable cargo (for example, citrus, apples, grapes, lychees, and so forth). Temperature probes that measure and record the internal temperature of the cargo at specific locations inside the reefer container are installed and connected to the reefer unit controller for subsequent temperature record verification. This practice is usually applied to fulfill the quarantine exemption requirement as stipulated by the sanitary laws and regulations of the importing countries. Required treatment duration, the number of probes and their installed locations inside the container are specified in the protocol which is mutually agreed upon between the authorities of the export and import countries.