River cancer is a species of the family of decapod crustaceans of the order Astacidea. The body of the cancer consists of:
- The cephalothorax, which has two parts: anterior (head) and posterior (thoracic), fused together. On the head part there is a sharp spine. On the sides in its grooves on the movable stems there are convex eyes. In front of the river cancer there are 2 pairs of thin antennae, among which one short, and the other long.
- Flat, segmented abdomen, consisting of 7 segments. The abdomen of the cancer has 5 pairs of bi-limb extremities, which freshwater uses for swimming. 6th and 7th pairs of abdominal legs form a caudal fin.
Pincers of freshwater armor apply for protection and attack. The females are smaller than the males and the segments of the abdomen are much wider than the cephalothorax. Males have more powerful claws. If the river cancer has lost a limb, then after the molting process, it will grow a new limb in place of the former. The color of river crayfish can vary due to the properties of water and habitat. Usually, the river cancer has a greenish-brown, brownish-greenish or blue-brown color.
River crayfish live in fresh water in Europe. This carcass is found in fresh clean water: in rivers, lakes, ponds, fast or flowing streams (up to 5 m deep, with depressions up to 12 m). River cancer goes to the hunt only at night. In the daytime, it lurks in all sorts of shelter - under the roots of trees, stones, burrows and other objects that can lie on the bottom. He protects his shelter from other crayfish. Freshwater can dig burrows up to 35 cm long. In summer, the river crayfish lives in shallow water, and in winter - it goes to depth in strong, clay or sandy soil.
As a man, river crabs have been used since ancient times. This is confirmed by the remains of animal shells found in the "kitchen piles" of the Neolithic period. Before serving, freshwater is processed by boiling in salt water, acquiring after it a reddish tint and a delicious, appetizing smell. Cooked crayfish are served to the table sprinkled with any herbs (parsley, celery, dill, etc.).
The coloration of crayfish during cooking is explained by the abundance of carotenoids in them. In the skin there is a pigment Astaxanthin, which in its purest form is a bright red color. Before heat treatment in living shell animals of the family of crustaceans, carotenoids are combined with proteins, and therefore the color of the freshwater cover is bluish, greenish or brown in color. During the boiling, these compounds disintegrate, and the released astaxanthin pigment gives the body red color.
Before cutting the crayfish, it should be slightly boiled in boiling water, so that the meat can be easily separated from the shell.
Useful properties of cancer of the river:
The most nutritious meat of river cancer is found in the abdomen and in the claws. A larger volume is contained in the abdomen.
Meat of the river cancer is white in color, with rare pink veins. It is very nutritious and excellent to taste. In its composition, the meat of cancer has a huge amount of proteins and a minimum fat content. Meat of this carcass refers to a high-quality diet and tasty product, which is easily digested and contains a huge number of useful elements. These include: proteins (up to 16%), calcium, vitamins E and B12. The meat of river crayfish contains a minimum of cholesterol and fats, as well as calories.
Of course, river cancer is not the record for the volume of meat in it compared to other freshwater families of crustaceans that people use for food. In the adult, there is little meat. For example, in a kilogram of shrimp contains about 400 grams of meat, and a kilogram of crayfish - about 100-150 grams. At the same time, river crayfish are 3-4 times more expensive than shrimps. Most likely, the use of crayfish is based on the attractive appearance of the dishes that he decorates.
The composition of the meat of river cancer contains a large number of sulfur, and therefore it should not be stored in aluminum cookware. After contact with the metal dishes, the meat turns black and spoils. It is recommended to use glassware.