Finally, Beluga, the largest of the caviar suppliers, weighs between 40 and 300 kg. The caviar that is obtained corresponds to about 15% of its weight. It is a robust and wild fish, difficult to catch and, above all, it reaches rivers to lay eggs only every 2-4 years. Beluga caviar has large, soft-grained grains and a color ranging from light gray to dark gray. Sturgeon fishing goes from February to May but the best quality is obtained in spring. n, caviar is subjected to a differentiated graduation based on the criteria of color, compactness, size, regularity, odor, brightness, taste and integrity. The only means of preservation is sodium chloride (salt), to which a bit of boric acid (borax) is added. The salt is added in very precise quantities and with extreme caution to avoid damaging the product: if the salt is low, the caviar deteriorates quickly, if it is too much, the caviar becomes dry and sticky.