Fish roe is an excellent source of nutrients, and just about every culture that has relied primarily on fishing for its nutritional needs has developed its own method for preserving roe for long periods of time. Without modern refrigeration, the best option is salting and drying. Famously, this method is used to produce Mediterranean Bottarga and traditional Russian Payusnaya caviar. Though there are similarities between the two products, they are ultimately quite different due to minor differences in timing and the required degree of drying.
Unlike Bottarga, which is made by salting whole sacs of Mullet roe before pressing and heavily drying them, Payusnaya (Russian for "pressed") caviar is made of Sturgeon caviar eggs that have already been extracted from the sac. Originally, the Sturgeon eggs used to make Payusnaya were those that broke during grading and packing for high grade caviar, or those that were damaged or too ripe.
By traditional standards, Payusnaya caviar may contain eggs from different species of Sturgeon, generally Osetra and Sevruga. This blending of different species produces a rich, layered flavor that will delight the palate. After being cleaned and separated from the sac and other tissue, the eggs are placed into a strong warm brine salted with natural sea salt, then removed after 1.5-2.5 minutes. The brine is drained and the caviar is placed into an artificial muslin sac for a certain period of time and hanged to drain. During this stage, the caviar loses up to 35% of its moisture, so the external layer of the eggs dries out and becomes more intense in flavor, though the eggs inside the sac remain fairly moist. At the final stage of processing, the partially dried roe is pressed into a kind of paste, reminiscent of a black grainy jam.
The traditional recipe for Russian Payusnaya caviar requires a higher dehydration level, which results in a texture similar to butter. It is still not as dry as Bottarga, which must be firm enough to be grated over a dish or sliced like a sausage. Current standards produce a version of Payusnaya with a consistency that allows it to be either spread on a sandwich or formed into small cubes that can be added to cooked dishes like mashed potatoes, rice, and pasta as seasoning, giving the dish a concentrated burst of rich flavor. Payusnaya caviar resembles a jam that is uniformly black in color. It is not particularly known for its appearance — it is made from the same fresh high-grade Sturgeon beads as other elite caviars, but it uses only those that were broken during extraction from the egg sac membrane. This does not alter the quality or flavor potential of this product, but it does mean it cannot be sold as premium, undamaged caviar. Due to its intense flavor, Payusnaya caviar is rarely served on its own — this highly concentrated product may contain three to four times more roe than an equivalent volume of regular caviar.
Payusnaya caviar is sold in standard glass jars or in tin cans, like other caviars, and should also be kept in the refrigerator at low temperatures. Due to its preparation method, however, it can last much longer than other caviars, so you can enjoy the impressive caviar flavor in your dishes for many weeks and even months after opening it — if you can commit to parceling this delicacy out in such small portions, that is. Once you've had a taste, we doubt you'll want to!