16
or xanthophylls, or the oxygenated derivatives of carotenes such as astaxanthin,
astacene, canthaxanthin, cryptoxanthin, lutein, neoxanthin, violaxanthin, and zeaxanthin. These pigments are present in esterified form or as protein complexes in the
shellfish. Raw shrimp are brown or green due to red orange colour of free and esterified carotenoids. Astaxanthin is the major red-orange coloured carotenoid in many
shrimp species which remains bound to proteins or chitin in shrimp (Venugopal
2020). The astaxanthin level of wild shrimps has been reported to vary between 740
and 1400 μg/100 g in edible meat portions, which again supports the argument for
including them as part of the daily diet (Sachindra et al. 2005). Yanar et al. (2004)
examined seasonal changes in the mussel tissue total caratenoid contents of the
most commercially important shrimp species (Penaeus semisulcatus and
Metapenaeus monoceros) in the north-eastern Mediterranean Sea caught in different seasons. They found considerably higher caratenoid contents for both species
during spring and summer than other seasons. It is reported that the total caretenoid
content varies according to the shrimp species and tissue (Sachindra et al. 2005;
Bono et al. 2012). They are high in carapace, followed by head and minimum in the
meat, varying from 17 to 200 mg per g (Venugopal 2020).
Raw shellfish species including shrimp have ash contents up to 2% that contains
minerals, which include sodium, potassium, calcium, magnesium and phosphorus
and microelements such as selenium, fluorine, iodine, cobalt, manganese, molybdenum, and others (Table 2.3). Shellfish contain nearly twice the amounts of minerals
as compared with finfish (Venugopal 2020). The two major sources of minerals for
marine organisms are seawater and feed. The mineral contents of shrimp species
can vary seasonally. Ca, K, P, Na, and Fe contents of two shrimp species (Penaeus
semisulcatus and Metapenaeus monoceros) from Eastern Mediterranean changed
seasonally (Yanar and Celik 2006).
2.1.2 Quality Changes in Shrimps/Prawns
In practice, shrimps are collected by trawl nets. Sometimes bagged trawl nets are
used. The nets are lowered to the bottom and withdrawn from the back of the ships.
Shrimp and other sea creatures are collected in the nets when the nets dragged at the
bottom. The net is pulled to the ship and shrimp and other sea creatures in the net
are discharged to the deck of the ship. Shrimp fishing is practically carried out at
night on sandy, muddy grounds. The type of the ground where the shrimp is caught
determines its quality. Shrimps caught from muddy ground can contain up to 30
million bacteria, while those caught in sandy bottoms contain less.
The quality of the shrimp begins to change when the trawl is withdrawn. Shrimp
trawls are drawn from the bottom of the sea from 1.5 to 5 h depending on the shrimp
concentration. In the case of trawling, the earliest caught shrimps die before they are
dumped to the deck and may begin to deteriorate. Especially during the shrimp
catching season, high temperature causes the shrimp to deteriorate while on the
trawler. After the trawl is unloaded to the ship’s deck, the shrimps are separated
2 Crustacean Shellfish
or xanthophylls, or the oxygenated derivatives of carotenes such as astaxanthin,
astacene, canthaxanthin, cryptoxanthin, lutein, neoxanthin, violaxanthin, and zeaxanthin. These pigments are present in esterified form or as protein complexes in the
shellfish. Raw shrimp are brown or green due to red orange colour of free and esterified carotenoids. Astaxanthin is the major red-orange coloured carotenoid in many
shrimp species which remains bound to proteins or chitin in shrimp (Venugopal
2020). The astaxanthin level of wild shrimps has been reported to vary between 740
and 1400 μg/100 g in edible meat portions, which again supports the argument for
including them as part of the daily diet (Sachindra et al. 2005). Yanar et al. (2004)
examined seasonal changes in the mussel tissue total caratenoid contents of the
most commercially important shrimp species (Penaeus semisulcatus and
Metapenaeus monoceros) in the north-eastern Mediterranean Sea caught in different seasons. They found considerably higher caratenoid contents for both species
during spring and summer than other seasons. It is reported that the total caretenoid
content varies according to the shrimp species and tissue (Sachindra et al. 2005;
Bono et al. 2012). They are high in carapace, followed by head and minimum in the
meat, varying from 17 to 200 mg per g (Venugopal 2020).
Raw shellfish species including shrimp have ash contents up to 2% that contains
minerals, which include sodium, potassium, calcium, magnesium and phosphorus
and microelements such as selenium, fluorine, iodine, cobalt, manganese, molybdenum, and others (Table 2.3). Shellfish contain nearly twice the amounts of minerals
as compared with finfish (Venugopal 2020). The two major sources of minerals for
marine organisms are seawater and feed. The mineral contents of shrimp species
can vary seasonally. Ca, K, P, Na, and Fe contents of two shrimp species (Penaeus
semisulcatus and Metapenaeus monoceros) from Eastern Mediterranean changed
seasonally (Yanar and Celik 2006).
2.1.2 Quality Changes in Shrimps/Prawns
In practice, shrimps are collected by trawl nets. Sometimes bagged trawl nets are
used. The nets are lowered to the bottom and withdrawn from the back of the ships.
Shrimp and other sea creatures are collected in the nets when the nets dragged at the
bottom. The net is pulled to the ship and shrimp and other sea creatures in the net
are discharged to the deck of the ship. Shrimp fishing is practically carried out at
night on sandy, muddy grounds. The type of the ground where the shrimp is caught
determines its quality. Shrimps caught from muddy ground can contain up to 30
million bacteria, while those caught in sandy bottoms contain less.
The quality of the shrimp begins to change when the trawl is withdrawn. Shrimp
trawls are drawn from the bottom of the sea from 1.5 to 5 h depending on the shrimp
concentration. In the case of trawling, the earliest caught shrimps die before they are
dumped to the deck and may begin to deteriorate. Especially during the shrimp
catching season, high temperature causes the shrimp to deteriorate while on the
trawler. After the trawl is unloaded to the ship’s deck, the shrimps are separated
2 Crustacean Shellfish