79
Crabs should be processed as quickly as possible for canning. Crabs should be
processed under conditions that limit the enzymatic activity that causes the deterioration of fresh flavours. They should be kept wet and cool immediately after catching. Cooking may be in boiling water or in retorts using pressurized steam. After
cooling, the edible meat is collected from the shells. The meat should be pressed
before putting it in the can. The cans should be packed tightly because some shrinkage occurs during the process (Featherstone 2016b).
An important problem with canned crab meat is discoloration. In canned crabs,
discoloration occurs with the formation of blue/black or grey/black pigments
(Featherstone 2016b). During the canning process, while a blue colour forms due to
the blood components of the crab meat, the brown associated with the mailard reaction, the black associated with the sulphite reactions of metals, the yellow associated with lipid oxidation and the red related to muscle pigments may be formed. In
addition, metals such as copper iron, muscle pH and moisture content, heat treatment, gender, seasonal factors have been reported to be effective in colour change
(Requena et al. 1999). It has been reported that blue discoloration can be reduced by
bleeding the crab before processing (Boon 1975). In a study conducted by Vijayan
and Balachandran (1981), it was found that there was a definite relationship between
the copper content of the crabs (Scylla serrata) and the blue colour change. They
also found that after thoroughly washing the crab carcass under running water, the
copper level decreased, and the blue discoloration was prevented.
Crab meat contains a copper-based hemocyanin that can form grey to blue-black
complexes when canned or pasteurized. Meats processed above about 87.7 °C often
change colour. Contamination of crab meat with metals, especially iron, can greatly
increase the blue discoloration. On the other hand, it is stated that ferric and ferrous
salts added to canned product may cause blue discoloration after processing
(Boon 1975).
Usually pasteurized crab meat is packed in aluminium cans. However, with the
advent of thermally stable polyethylene packaging, the crab products were sold in
laminated bags (Galetti 2010). Blue crab meat is pasteurized in different packages
including steel boxes, aluminium boxes, plastic boxes, non-barrier bags and barrier
bags. It was determined that crab meat pasteurized in plastic and aluminium cans
had better quality and longer shelf life than those put in steel tin cans. The lowest
quality and shortest shelf life are determined in the product packaged in oxygen
barrier bags (Gates et al. 1993). Lacquered containers should be used for canned
crab. Sometimes it is necessary to double-varnished boxes to completely protect
the crabs from contact with the tin. Parchment is also used in some cases
(Featherstone 2016b).
2.2.4.6 Crab Cakes
To produce crab cakes, the minced crab meat is mixed with spices or sauce, covered
with dough or potatoes are added. Milk, eggs, mayonnaise can be used for the crab
cake and green peppers and onions can be added. Crab cakes are either freshly mar2.2 Crabs
Crabs should be processed as quickly as possible for canning. Crabs should be
processed under conditions that limit the enzymatic activity that causes the deterioration of fresh flavours. They should be kept wet and cool immediately after catching. Cooking may be in boiling water or in retorts using pressurized steam. After
cooling, the edible meat is collected from the shells. The meat should be pressed
before putting it in the can. The cans should be packed tightly because some shrinkage occurs during the process (Featherstone 2016b).
An important problem with canned crab meat is discoloration. In canned crabs,
discoloration occurs with the formation of blue/black or grey/black pigments
(Featherstone 2016b). During the canning process, while a blue colour forms due to
the blood components of the crab meat, the brown associated with the mailard reaction, the black associated with the sulphite reactions of metals, the yellow associated with lipid oxidation and the red related to muscle pigments may be formed. In
addition, metals such as copper iron, muscle pH and moisture content, heat treatment, gender, seasonal factors have been reported to be effective in colour change
(Requena et al. 1999). It has been reported that blue discoloration can be reduced by
bleeding the crab before processing (Boon 1975). In a study conducted by Vijayan
and Balachandran (1981), it was found that there was a definite relationship between
the copper content of the crabs (Scylla serrata) and the blue colour change. They
also found that after thoroughly washing the crab carcass under running water, the
copper level decreased, and the blue discoloration was prevented.
Crab meat contains a copper-based hemocyanin that can form grey to blue-black
complexes when canned or pasteurized. Meats processed above about 87.7 °C often
change colour. Contamination of crab meat with metals, especially iron, can greatly
increase the blue discoloration. On the other hand, it is stated that ferric and ferrous
salts added to canned product may cause blue discoloration after processing
(Boon 1975).
Usually pasteurized crab meat is packed in aluminium cans. However, with the
advent of thermally stable polyethylene packaging, the crab products were sold in
laminated bags (Galetti 2010). Blue crab meat is pasteurized in different packages
including steel boxes, aluminium boxes, plastic boxes, non-barrier bags and barrier
bags. It was determined that crab meat pasteurized in plastic and aluminium cans
had better quality and longer shelf life than those put in steel tin cans. The lowest
quality and shortest shelf life are determined in the product packaged in oxygen
barrier bags (Gates et al. 1993). Lacquered containers should be used for canned
crab. Sometimes it is necessary to double-varnished boxes to completely protect
the crabs from contact with the tin. Parchment is also used in some cases
(Featherstone 2016b).
2.2.4.6 Crab Cakes
To produce crab cakes, the minced crab meat is mixed with spices or sauce, covered
with dough or potatoes are added. Milk, eggs, mayonnaise can be used for the crab
cake and green peppers and onions can be added. Crab cakes are either freshly mar2.2 Crabs