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2.2.4 Crab Processing and Preservation
2.2.4.1 Alive Transportation of Crabs
Crab meat is very sensitive and can change its quality in a very short time. Therefore,
it is very important to keep the crabs alive before consumption or before the process.
Previously, the live consumption of crabs was limited to fishing zones. However, the
fact that crabs must be transported live to other regions has resulted in the development of methods of transporting them alive.
Keeping alive of crabs starts first on the ship’s deck at sea. Live crabs should be
processed immediately after capture if possible. If they are exposed to sunlight and
wind, they die quickly. If the time and weather conditions are appropriate, they
should be stacked as soon as they are captured and, in any case, must be placed
directly in the boxes or on the bottom of the ship. Crabs should be packed in top
ventilated boxes as close as possible to each other. Thus, they are prevented from
being damaged by fighting with each other during transportation. The full boxes
must be protected from the sun and wind. Wet straw or sawdust on the bottom of the
boxes will extend the shelf life. Crab transport should be carried out as soon as possible. Especially, it should be transported at night when the air temperature is low
(Edwards and Early 1978; Borderias 2012). The crab, which is individually tied, is
tightly packed in the carton in its vertical position with the claws at the top. In case
of air transport, liner inserted to the boxes are used for sealing. A few layers of paper
or newspapers are placed at the bottom of these boxes. Thus, the liquid to be leaked
from the crab is impregnated. The mortality rate of crabs transported in this way is
generally reported to be less than 10%. In some countries, such as the Philippines,
the crab is placed in cartons covered with plastic sheets (after connecting separately). Cartons and plastic sheets have ventilation holes. The crab is also packaged
in perforated polystyrene boxes (Mohamed and Devaraj 1997).
Under normal conditions, crabs can only live out of water for a short time. Longer
life out of sea water depends on environmental factors such as temperature and
humidity. If these factors are optimally adjusted, they can live longer. In a study, it
was shown that crabs can live outside the water for 24–210 h depending on the
humidity level in the atmosphere (Mohamed and Devaraj 1997). Relative humidity
significantly affects the survival time of the crab. In the case of saturated relative
humidity, the crab loses less weight. If the crab loses 10% of its weight, it dies
(Gillespie and Burke 1991).
The activity of live crustaceans decreases as the temperature decreases. Handling
of animals at low temperatures can be easier and any kind of transport should be less
stressful. The decrease in the activity will reduce the amount of waste. The starvation period (24–48 h) will also reduce the production of waste. The gradual reduction in temperature and starvation time should be considered as pre-treatments for
live transport or dry transport (Jacklin and Combes 2007a).
2 Crustacean Shellfish
2.2.4 Crab Processing and Preservation
2.2.4.1 Alive Transportation of Crabs
Crab meat is very sensitive and can change its quality in a very short time. Therefore,
it is very important to keep the crabs alive before consumption or before the process.
Previously, the live consumption of crabs was limited to fishing zones. However, the
fact that crabs must be transported live to other regions has resulted in the development of methods of transporting them alive.
Keeping alive of crabs starts first on the ship’s deck at sea. Live crabs should be
processed immediately after capture if possible. If they are exposed to sunlight and
wind, they die quickly. If the time and weather conditions are appropriate, they
should be stacked as soon as they are captured and, in any case, must be placed
directly in the boxes or on the bottom of the ship. Crabs should be packed in top
ventilated boxes as close as possible to each other. Thus, they are prevented from
being damaged by fighting with each other during transportation. The full boxes
must be protected from the sun and wind. Wet straw or sawdust on the bottom of the
boxes will extend the shelf life. Crab transport should be carried out as soon as possible. Especially, it should be transported at night when the air temperature is low
(Edwards and Early 1978; Borderias 2012). The crab, which is individually tied, is
tightly packed in the carton in its vertical position with the claws at the top. In case
of air transport, liner inserted to the boxes are used for sealing. A few layers of paper
or newspapers are placed at the bottom of these boxes. Thus, the liquid to be leaked
from the crab is impregnated. The mortality rate of crabs transported in this way is
generally reported to be less than 10%. In some countries, such as the Philippines,
the crab is placed in cartons covered with plastic sheets (after connecting separately). Cartons and plastic sheets have ventilation holes. The crab is also packaged
in perforated polystyrene boxes (Mohamed and Devaraj 1997).
Under normal conditions, crabs can only live out of water for a short time. Longer
life out of sea water depends on environmental factors such as temperature and
humidity. If these factors are optimally adjusted, they can live longer. In a study, it
was shown that crabs can live outside the water for 24–210 h depending on the
humidity level in the atmosphere (Mohamed and Devaraj 1997). Relative humidity
significantly affects the survival time of the crab. In the case of saturated relative
humidity, the crab loses less weight. If the crab loses 10% of its weight, it dies
(Gillespie and Burke 1991).
The activity of live crustaceans decreases as the temperature decreases. Handling
of animals at low temperatures can be easier and any kind of transport should be less
stressful. The decrease in the activity will reduce the amount of waste. The starvation period (24–48 h) will also reduce the production of waste. The gradual reduction in temperature and starvation time should be considered as pre-treatments for
live transport or dry transport (Jacklin and Combes 2007a).
2 Crustacean Shellfish