Caviar, as its name implies, is made from fish eggs. In fact, strictly speaking, only the sauce made of sturgeon eggs can be called caviar. Sturgeon spawns in Volga River and other inland rivers twice a year, which is a good season to collect fish eggs. Astrakhan, an ancient city located in the estuary delta, is the largest production and processing base of sturgeon roe in the world because of its superior geographical position. Caviar is high in protein and minerals, and contains no cholesterol. It is a food for nourishing the body and beauty beauty. Large and transparent black caviar is the top grade, the color is shiny black or dark brown, the head is uniform, and there is no adhesion between grains. The method of making caviar is very simple: dig out the fish sac from the fish cavity, separate the caviar from the attached tissues (mature caviar is easy to peel off from the ovary), rinse it, and add a proper amount of fine salt for curing. The purpose of adding salt is to keep fresh, because the protein and fat content of roe is as high as 30%, and it is easy to deteriorate without salt.