36
Chilling On-Board
Shrimps must be taken care of when it comes to the deck of the trawler. Shrimp
catching should be done in a reasonable time. Unnecessarily extending time can
damage shrimps in the nets. Shrimps should be processed quickly after coming to
the deck. Exposure to sun and wind on deck should be avoided. Otherwise, the
spoilage starts immediately. Firstly, shrimps must be separated from the other
caught. Then shrimps should be washed with sea water and the sand, mud and bacteria should be removed.
Icing
The most common method for preserving the freshness of shrimps is icing. For
optimum results, the ice method and ice quality should be considered. The shelf life
of iced shrimp can be extended for a few days. The time from shrimp death to icing
is critical. Immediately after death, autolytic and bacterial enzymes begin to break
down in proteins, lipids, and carbohydrates. To reduce the bacterial load of the
shrimp, it is inevitable to wash it thoroughly and reduce the ambient temperature.
After separation and washing, the raw shrimps are drained and packed in ice in
boxes. The time between catching and chilling must be short. A 1-h delay can cause
deterioration, especially on a warm day (Anonymous 1972).
Ice-chilling of seafood is mainly due to the flow of cold melting water over the
product. When the product to be cooled is hotter, the melting rate will be higher, so
cooling is applied automatically and quickly without the risk of freezing. In addition
to good cooling conditions, melting water also helps to remove blood, bacteria, etc.
The chilling of the product to the temperature, which is the melting point of the ice,
can be achieved by surrounding of the product completely with ice (Gokoglu 2002).
Boxes should not be deeper than 200 mm to prevent crushing of shrimps on the
bottom. A thin layer of ice or broken ice block should be placed on the bottom of the
box. A layer of shrimp should be placed on a layer of ice not higher than 50 mm and
should be covered with a little more ice. Shrimp and ice should be added in this way
until the box is filled. Boxes should not be overfilled, otherwise shrimps may be
crushed. Shrimp should be covered with ice until landed. In summer, 1 kg of ice
may be required for 1 kg of shrimp. Storage temperature should be kept at 1–3 °C
so ice melts slowly (Anonymous 1972). The maximum storage time of the shrimp
in ice varies up to 3 weeks depending on the washing process and the effectiveness
of the icing after washing. Shrimp tissue is still biochemically active, although
shrimps lose their vitality in a short time after their capture. Therefore, they enter an
extremely rapid deterioration process due to the activity of both bacteria and original enzymes (autolysis). Shrimps stored in crushed ice will remain in good condition
for 4 days. But for better results, shrimps should be processed within 2 days.
Shrimps stored on ice for 6 days, the typical aroma disappear, and the meat softens;
in this case it becomes difficult to remove the shell. After 8 days the fishy odour and
aroma develops.
2 Crustacean Shellfish
Chilling On-Board
Shrimps must be taken care of when it comes to the deck of the trawler. Shrimp
catching should be done in a reasonable time. Unnecessarily extending time can
damage shrimps in the nets. Shrimps should be processed quickly after coming to
the deck. Exposure to sun and wind on deck should be avoided. Otherwise, the
spoilage starts immediately. Firstly, shrimps must be separated from the other
caught. Then shrimps should be washed with sea water and the sand, mud and bacteria should be removed.
Icing
The most common method for preserving the freshness of shrimps is icing. For
optimum results, the ice method and ice quality should be considered. The shelf life
of iced shrimp can be extended for a few days. The time from shrimp death to icing
is critical. Immediately after death, autolytic and bacterial enzymes begin to break
down in proteins, lipids, and carbohydrates. To reduce the bacterial load of the
shrimp, it is inevitable to wash it thoroughly and reduce the ambient temperature.
After separation and washing, the raw shrimps are drained and packed in ice in
boxes. The time between catching and chilling must be short. A 1-h delay can cause
deterioration, especially on a warm day (Anonymous 1972).
Ice-chilling of seafood is mainly due to the flow of cold melting water over the
product. When the product to be cooled is hotter, the melting rate will be higher, so
cooling is applied automatically and quickly without the risk of freezing. In addition
to good cooling conditions, melting water also helps to remove blood, bacteria, etc.
The chilling of the product to the temperature, which is the melting point of the ice,
can be achieved by surrounding of the product completely with ice (Gokoglu 2002).
Boxes should not be deeper than 200 mm to prevent crushing of shrimps on the
bottom. A thin layer of ice or broken ice block should be placed on the bottom of the
box. A layer of shrimp should be placed on a layer of ice not higher than 50 mm and
should be covered with a little more ice. Shrimp and ice should be added in this way
until the box is filled. Boxes should not be overfilled, otherwise shrimps may be
crushed. Shrimp should be covered with ice until landed. In summer, 1 kg of ice
may be required for 1 kg of shrimp. Storage temperature should be kept at 1–3 °C
so ice melts slowly (Anonymous 1972). The maximum storage time of the shrimp
in ice varies up to 3 weeks depending on the washing process and the effectiveness
of the icing after washing. Shrimp tissue is still biochemically active, although
shrimps lose their vitality in a short time after their capture. Therefore, they enter an
extremely rapid deterioration process due to the activity of both bacteria and original enzymes (autolysis). Shrimps stored in crushed ice will remain in good condition
for 4 days. But for better results, shrimps should be processed within 2 days.
Shrimps stored on ice for 6 days, the typical aroma disappear, and the meat softens;
in this case it becomes difficult to remove the shell. After 8 days the fishy odour and
aroma develops.
2 Crustacean Shellfish