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2.2.4.3 Chilling
The post-harvest conditions of crabs can cause stress responses that can lead to
reduced quality and survival. Chilled packaging method has been shown to minimize respiratory requirements and prolong transport time. Reduced oxygen consumption will reduce the sensitivity to stress (Ninlanon 2011).
Crabs are usually kept alive or in ice to prevent rapid quality deterioration. It is
then stored in the refrigerator, which runs between 2 °C and 4 °C until melted ice or
consumption (Fotedar and Evans 2011).
Raw or cooked storage of crabs also affects cold storage time. In a study, the
shelf life of cooked crab (Scylla serrata) meat was determined as 8–9 days at
25–28 °C, 6 days at 6.5–7.5 °C and 11 days at 0 °C (George and Gopakumar 1988).
The shelf life of the cooked and uncooked crab (Portunus pelagicus) stored in ice
was determined as 14 and 10 days, respectively (Balasaraswathy et al. 2008).
In another study, live crabs were kept in tanks where sea water was provided at
ambient temperature and then stored in four different conditions. The first group
were kept on ice on 4 °C, the second group on 4 °C, the third group were kept on ice
at 20 °C for 4 h and then at 4 °C for 16 h by simulating the market conditions and
the fourth group at 20 °C was stored. According to the results of the study, the shelf
lives of unprocessed crabs (Carcinus maenas, Necora puber and Cancer pagurus)
were determined to be 9–11 days on ice at 4 °C; 13–29 days at 4 °C; under simulated supermarket conditions (4 °C and 20 °C) 5–7 days and 2–16 days respectively
(Robson et al. 2007).
2.2.4.4 Freezing
Crabs should be frozen after cooking (not before). When crabs are frozen and subsequently cooked, it is extremely difficult to remove the meat and yield is low.
When the crabs are frozen as whole, losses of the claws and legs are inevitable. The
extracted meats are either frozen in cardboard boxes as consumer packs or in large
blocks for catering manufacturers. They are usually glazed and packed in outer
carton for storage. White and black meats can be frozen in separate packages. Or
they can be packed in the same package with plastic film or parchment. Dressed
crab can be frozen in plastic bags. Barbecue claws should be frozen in an airflow
freezer due to their irregular shapes. However, homogeneous packages can be contact frozen. Freezing should be done quickly. First, the product must be cooled from
0 to −5 °C for no longer than 2 h. It should then be frozen. Unpackaged blocks
should be glazed after being removed from the freezer. Immediately after freezing,
the crabs should be taken to the cold store immediately. If possible, frozen crabs
should be stored at −20 to −25 °C (Edwards and Early 1978).
In a study comparing freshly caught and then frozen crabs (Scylla serrata) after
storage for 14 days on ice, the crabs were frozen in a plate freezer at −40 °C, coated
with polyethylene paper and packaged in a cardboard box and stored at −23 °C. At
the end of the study, fresh frozen crabs remained acceptable for up to 52 weeks. On
2 Crustacean Shellfish
2.2.4.3 Chilling
The post-harvest conditions of crabs can cause stress responses that can lead to
reduced quality and survival. Chilled packaging method has been shown to minimize respiratory requirements and prolong transport time. Reduced oxygen consumption will reduce the sensitivity to stress (Ninlanon 2011).
Crabs are usually kept alive or in ice to prevent rapid quality deterioration. It is
then stored in the refrigerator, which runs between 2 °C and 4 °C until melted ice or
consumption (Fotedar and Evans 2011).
Raw or cooked storage of crabs also affects cold storage time. In a study, the
shelf life of cooked crab (Scylla serrata) meat was determined as 8–9 days at
25–28 °C, 6 days at 6.5–7.5 °C and 11 days at 0 °C (George and Gopakumar 1988).
The shelf life of the cooked and uncooked crab (Portunus pelagicus) stored in ice
was determined as 14 and 10 days, respectively (Balasaraswathy et al. 2008).
In another study, live crabs were kept in tanks where sea water was provided at
ambient temperature and then stored in four different conditions. The first group
were kept on ice on 4 °C, the second group on 4 °C, the third group were kept on ice
at 20 °C for 4 h and then at 4 °C for 16 h by simulating the market conditions and
the fourth group at 20 °C was stored. According to the results of the study, the shelf
lives of unprocessed crabs (Carcinus maenas, Necora puber and Cancer pagurus)
were determined to be 9–11 days on ice at 4 °C; 13–29 days at 4 °C; under simulated supermarket conditions (4 °C and 20 °C) 5–7 days and 2–16 days respectively
(Robson et al. 2007).
2.2.4.4 Freezing
Crabs should be frozen after cooking (not before). When crabs are frozen and subsequently cooked, it is extremely difficult to remove the meat and yield is low.
When the crabs are frozen as whole, losses of the claws and legs are inevitable. The
extracted meats are either frozen in cardboard boxes as consumer packs or in large
blocks for catering manufacturers. They are usually glazed and packed in outer
carton for storage. White and black meats can be frozen in separate packages. Or
they can be packed in the same package with plastic film or parchment. Dressed
crab can be frozen in plastic bags. Barbecue claws should be frozen in an airflow
freezer due to their irregular shapes. However, homogeneous packages can be contact frozen. Freezing should be done quickly. First, the product must be cooled from
0 to −5 °C for no longer than 2 h. It should then be frozen. Unpackaged blocks
should be glazed after being removed from the freezer. Immediately after freezing,
the crabs should be taken to the cold store immediately. If possible, frozen crabs
should be stored at −20 to −25 °C (Edwards and Early 1978).
In a study comparing freshly caught and then frozen crabs (Scylla serrata) after
storage for 14 days on ice, the crabs were frozen in a plate freezer at −40 °C, coated
with polyethylene paper and packaged in a cardboard box and stored at −23 °C. At
the end of the study, fresh frozen crabs remained acceptable for up to 52 weeks. On
2 Crustacean Shellfish