CAVIAR
Caviar is among the most expensive and luxury foods you can eat, even though it's really nothing more than fish roes. Surely the price compared to other animals is way out of this world, although the fish roes are much more rare and hence the price difference. Nowadays, there are farms that produce fish caviar and it's of almost the same quality as wild fish eggs, and its price is lower. The true caviar, is made of sturgeon roe, but also other fish species are used for making this delicacy. Of course, anything but beluga sturgeon caviar is different, but some chefs actually prefer the somehow cheaper caviar of osetra or sevruga. To American caviars, one that stands out is the paddlefish caviar, coming from Missisipi and Alabama. There are also cheap caviars made of salmon or trout roe, and their cost is relatively low due to availability. Caviar is normally served as a dish in itself (since it tastes good and is expensive), maybe as an appetizer or as a garnish on some other dishes, often a fish fillet.
What is the nature of caviar? Whether it's beluga, osetra, or paddlefish caviar it is essentially fish eggs. Fish ovaries (called roes) can accumulate thousands or even millions of eggs that are essential for spawning. The same thing happens in humans, by the way, although with some modifications. The nature of these eggs is the key to their nice taste. Eggs are a great storage of high concentrations of nutrients, including fat, amino acids, and DNA and RNA - a very tasty mix of flavorful molecules! The eggs that are used for making caviar should be in a perfect developmental stage. If they are too young and immature, they don't taste much; if they are too old then they are too soft and fragile, and may also smell. The perfect eggs are in-between these two extremes.
These eggs are then salted lightly, and since salt creates a slight osmotic pressure, it makes the egg more firm. Salt also helps to activate certain protein-crosslinking enzymes that further enhance the process of solidifying the egg. Another role of salt in making caviar is the activation of digestion of proteins, so that more flavorful amino acids are created within the eggs. The proteins that still reside within the egg will take on a different attraction potential to each other, so that they form a half-jelly-like texture inside the egg. All these processes - solidifying, creation of flavorful substances, and making of a fine texture - make up the production of caviar.
The most prized caviar is probably the one coming from the Iran - Russia border around the rivers that flow into the Caspian Sea, where the sturgeon lives and can be used for caviar making. There are also farms that produce caviar, and in some cases they are really good at that, thanks to a more clear environment. Caviar making starts with catching the fish, stunning them and picking out the roes prior to killing. The roes are then placed over a special "net" that will loosen and separate the eggs from the ovaries. Then, salt is added, and after a few moments the eggs are canned and stored at around -4 C/25 F, just above the freezing point of caviar (which is lowered by the salt). The rarest caviar is the Beluga caviar and it's also the most expensive. There are also more common ones like Osetra and Sevruga, and they all have different flavors and colors. Also, as we already mentioned, there are cheaper caviars made of e.g. salmon or cod, as well as other fish species. And don't forget to try the American paddlefish caviar as well!