fish

Crabs

Generality

Crabs are animal organisms of the aquatic type; they belong to the Subphilum of the Crustaceans, the Order of the Decapods, the Suborder of the Pleocyemata and the Infraorder of the Brachyura .

Crabs are amphibious animals because, by sealing the gills, as well as in the water they also survive in the open air (specific feature of the Brachiuri, not shared by Macruri and Stomatopodi ).

From the morphological point of view, the crabs make use of a robust armor (better called carapace, which covers both the body and the limbs), two frontal claws (with which it hunts and defends) and eight side legs appointed for movement and I swim.

The body of the crabs (also called capotorace ) is more or less discoid, of flattened shape, with the function of containing the organs. The crabs have the mouth, the eyes and the claws in frontal position, while laterally the legs are articulated and posteriorly - folded and recessed in the body - they hide the belly where the eggs develop.

Crabs are medium-sized omnivores and feed on fresh algae, small echinoderms, actinias and all kinds of organic debris; they have saprophagous habits.

The crabs represent a very heterogeneous group (Infraorder) and, to classify them in an orderly manner, it would be appropriate to differentiate 5 superfamilies: Dromiacea, Raninoida, Cyclodorippoidea, Ebrachyura and Thoracostremata . However, this kind of subdivision encompasses many species not assigned to human consumption, therefore only the most used crabs in the customary diet will be considered below.

Edible crabs of Italy

Numerous species of crabs live in Italy. Contrary to what many people think, crabs do NOT live only in salt water, but it is also true that (in our country) there is only one species of fresh water.

Edible sea crabs:

  • Crab, woolly or hairy crab ; binomial nomenclature: Portunus puber . It is the crab with the most combative character; it is covered with a thin down, has a reddish brown or mud gray color, stained with blue, black or red, with small red eyes and two particularly massive and powerful frontal claws. The crab reaches 12cm in diameter and is fished more in the spring and summer period, when its meats are tastier. Of the same family ( Portunidi ), but belonging to different Species, are: Portunus corrugatus or grancella (it frequents posidonia and sand / mud meadows), Portunus Holsatus (it frequents the sandy expanses below which it hides) and the Portunus depurator (small, reddish brown).
  • Granciporro ; binomial nomenclature: Cancer pagurus . It is predominantly nocturnal; in adult age (dimensions that touch the 30cm of diameter) it does not colonize easily accessible bathymetries and, sinking gradually, it can reach depths of over 100m. The granciporro has a particularly squat appearance, with large and powerful claws; unlike the previous one, it is slow, not very aggressive and is totally glabrous with a dark orange color, tending to brown. After the granseola, it is the largest and most delicious crab of our seas.
  • Porcelain crab, sleepy crab; binomial nomenclature: Dromia vulgaris . It is more stocky than the crab and, superficially, is NOT smooth and clean; it is distinguished by the peculiarity of growing large sponges on the back of the carapace, with which it hides and protects itself. It has habits similar to the granciporro even if it is slower, placid and smaller.
  • Granseola, spider crab, spider crab ; binomial nomenclature: Maja squinado . It is very similar to a spider by virtue of its long legs and heart-shaped body; it represents the largest crab in the entire category (it can reach 2kg in weight) and also, like the crab, presents mainly nocturnal habits, while with advancing age it tends to migrate towards greater depths.

Edible river crabs

  • River crab ; Binomial nomenclature: Potamon fluviatile . It has a greyish-brown color with yellowish streaks, reaches a body diameter of 3.5-4.5cm and lives in the burrows at the edges of the streams or in pools of fresh water; it has nocturnal habits and is particularly active in spring and autumn. Currently it is an endangered species because it suffers the presence of pollution; its meats, as well as those of the crayfish, are extremely valuable.

Fishing

All crabs are easily catchable fishery products, although with very different techniques depending on the species in question. Freshwater crabs are captured by hand, as are crab crabs and small specimens of crab, porcupine crab and spider crab (all crabs that occupy the sub-coast). On the contrary, adult crab crab and ganseola crabs are trapped with "pots" placed on high bathymetries, but fortunately these cannot reach 100-150m where older specimens persist.

Gastronomic hints and nutritional characteristics

Nutritional composition of the Crab, canned - Reference values ​​of the INRAN Food Composition Tables
Nutritional composition per 100 grams of edible part. Crab, in a box:

Edible part100.0%
water79, 2g
Protein18, 1g
Lipids TOT0, 9g
Saturated fatty acids- g
Monounsaturated fatty acids- g
Polyunsaturated fatty acids- g
Cholesterol101, 0mg
TOT Carbohydrates0.0g
Starch0.0g
Soluble sugars0.0g
Dietary fiber0.0g
Power81, 0kcal
Sodium550, 0mg
Potassium100, 0mg
Iron2, 8mg
Football120, 0mg
Phosphorus32, 0mg
Thiaminetr
Riboflavin0.05 mg
Niacin1, 10mg
Vitamin Atr
C vitamintr
Vitamin E- mg

Crabs are very delicious crustaceans; those of big dimensions (especially granseola and granciporro) are successfully used in the preparation of Catalan or boiled, while smaller crabs (crab of rena) represent a very tasty ingredient for sauces (with tomato or without) of first courses or stews. The only portion of crab waste (to be eliminated with cleaning) is the belly.

NB . To eat crabs with ease it is essential to use the appropriate pliers for breaking the claws; using your teeth could seriously compromise their integrity!

The crabs have a very high edible ration consisting essentially of the chitinous carapace; this, although not digestible by man, after a specific industrial processing (alkaline treatment), undergoes the conversion of chitin (polysaccharide) into chitosan, a "dietetic" molecule used in the formulation of some slimming supplements. Chitosan is considered a lipid chelator and as such should reduce intestinal absorption of dietary fats, moderating the amount of energy introduced with food; unfortunately, its application has not shown a worthy effectiveness.

Crabs are highly perishable foods. If stored (even in refrigeration) they activate the enzymatic degradation of free amino acids and muscle proteins early; this favors the onset of the typical ammonia smell.

Obviously, bacterial proliferation accelerates the decay process and increases the release of ammonium (although not always the vaguely pungent smell nullifies edibility). Enzymatic degradation can be stopped by cooking or freezing.

Crabs are potentially allergenic foods and their presence in the diet must NOT affect: pregnant women, nurses and children of weaning age.

Unfortunately, there are not many data regarding the nutritional intake of crabs; however, considering the Subphylum of belonging (crustaceans), it is likely to assume that they are characterized by:

  1. Low energy intake (<100kcal / 100g)
  2. Remarkable protein intake with high biological value
  3. Low lipid intake (probably characterized by a good concentration of polyunsaturated fatty acids)
  4. Traces of simple carbohydrates
  5. Medium or high cholesterol content (about 100mg / 100g)
  6. Excellent supply of water-soluble vitamins (from group B, especially thiamine, riboflavin and niacin)
  7. Satisfactory intake of iron and potassium.

WARNING! The reader DO NOT misunderstand the crabmeat (of which below we report the nutritional values) with the surimi ; the latter is a surrogate formulated with various fishery products, therefore (from the chemical point of view) it does not even vaguely resemble the crustacean proper.

Bibliography:

  • Edible animals of the Italian seas - A. Palombi, M. Santarelli - pag 364
  • Food Microbiology - JM Jay, MJ Loaessner, DA Golden - Springer - 126-127