During Transit: Temperature control is most essential and must be
strictly maintained. Daily records showing the temperature in each
compartment are to be kept for each watch. Nowadays automatic
temperature recorders keep a continuous record of temperatures. During
transit of chilled meat, a certain amount of CO2, (10% by volume) is
introduced to preserve the meat, Excessive CO2, can discolour the
consignment. Hence it is essential to keep a record and control of CO2
concentration. An instrument called a thermoscope is used to monitor the
concentration of CO2. Conversely, in the case of fruits, the ripening of the
fruit causes evolution of CO2, which, if present in concentrations of above
5% spoils the fruit. This excess CO2, can be dissipated by allowing fresh
precooled air occasionally into the hold, taking care not to cause large
variations in temperature.
During Discharge: Prior to discharge a cargo surveyor is generally
called to check the transit temperature and CO2. records. If the
concentration of CO2, is higher than 7% the compartment must be vented
with fresh air prior to man entry for discharge.
Here are some properties of refrigerated cargoes with their carrying
Apples (-1 to 2-C) should be in good condition. Can taint other cargoes.
Bananas (around 12-C) are carried as a special trade. They are shipped on
their stems in a hard, unripe state. Daily inspections of the compartment
are to be made and any ripe fruit plucked. Too low temperatures can
permanently arrest the ripening process. Shipment is done in such a state
as to arrive at the discharge ports and reach the markets, ripe and ready for
Butter is carried frozen, while cheese (3-to 6C) is chilled. Both are liable to
Citrus Fruits (3- to 7C) leave behind a strong, fruity smell which must be
removed before loading any other cargo.
Chilled beef (-2-C) should not have any whitish, mould marks.
It is hung from hooks, not too close together, to permit ventilation and
Frozen meat (-10-C) Soft carcasses should be rejected and bloodstained
wrapping regarded with suspicion. Maybe loaded in smaller pieces in bags.
Eggs are fragile and must be handled carefully. They are easily tainted and
may require stowage in a separate compartment.
Drugs and experimental samples are often sent in refrigerated ships.
Instructions of the shipper must be strictly followed.
Chemicals and gases are shipped in refrigerated condition in special ships.
Their carriage is a separate subject in itself.