Crustaceans

Classification and description

Shellfish are invertebrate aquatic creatures belonging to the Arthropod group; they are equipped with articulated appendages dedicated to movement, while the body is provided with a resistant casing composed of a matrix based on calcareous salts and is called carapace. The carapace, in the larger crustaceans, constitutes a real shell that protects the head (capotorace) and partly the chest (cephalothorax).

The presence of 10 thoracic legs distinguishes a group of crustaceans also called Decapods; of these, many are characterized by a pair of front legs transformed into pincers, the claws, while frontally two pairs of appendages can be distinguished: the antennas and the antennas. Crustaceans generally live immersed in water, on various seabeds and at various depths, even if a part of them, the Brachiuri, possess the ability to remain dry for a limited period of time (amphibious characteristic).

Subdivision of Decapod crustaceans

EDIBLE Decapod crustaceans can be divided as follows:

MACRURI: long abdomen, stretched with a tail-shaped fan-shaped fin (eg lobster, lobster, shrimp, etc.)
BRACHIURI: short abdomen without fan, folded under the capotorace (eg crab, )
STOMATOPODS: provided with two mouth appendages with attached raptor claws formed by a toothed movable article that folds over the segment itself (eg canocchia etc.)

storage

Why aren't crustaceans long?

The high amount of free amino acids significantly promotes the formation of nitrogen, which is already present in quantities of 300mg per 100g of edible portion. Free nitrogen is responsible for the bad smell of preserved crustaceans, but the amount naturally present in the live animal's flesh would not be sufficient to justify it; two essential mechanisms contribute to the formation of the bad smell of dead crustaceans:

The own enzymatic action
Anaerobic bacterial action

These are parallel processes that intervene by degrading the muscle proteins and transforming the trimethylamine oxide (TMAO) into trimethylamine (TMA), a volatile compound responsible for the typical "fishy smell". Ultimately, the high quantity of free amino acids and free nitrogen, associated with the enzymatic and bacterial action on dead animals, determines a very limited preservation of fresh crustaceans, beyond which there is a strong smell of ammonia and poorly preserved fish.