After the eggs are obtained from the fish, there are three common ways in which caviar is processed to preserve the product and keep its quality for longer. All the methods use salt as the primary agent in curing the roe to increase its flavor as well as its shelf life, but the amount of salt and method of preservation can change depending on the quality and type of roe being cured.
Least salt : The highest quality method for preserving caviar is the malossol process, which is best for enhancing the flavor while reasonably increasing the shelf life of the product. In some parts of the world, malossol caviar can have borax added to further reduce the required salt content.
More salt : Caviar that would typically be cured as malossol, but is second in quality due to overly ripe, soft or damaged eggs, typically becomes pressed caviar. With this method, the eggs are first cured with slightly more salt, and then pressed into a hard jam-like substance. Because of higher salt and more concentrated flavor, pressed caviar is revered by connoisseurs for its strong taste.
Most salt : A grade down from pressed caviar is the semi-preserved, or “salted” caviar, which contains a much higher salt content to increase the product’s shelf stable-ness. Typically only used in producing lower quality fish roes, this method often compromises taste for stability with a typical salt content of 8%. Additional preservatives, such as Sodium Benzoate, are sometimes added to certain types of semi-preserved caviar.
After the initial curing and preservation process, the roe will have different preparation, finishing and storage needs based on what salting method was used. Malossol caviar is usually put in banded tins or vacuum sealed containers, and stored at temperatures ranging from 26° to 36° F for about a two month fresh caviar shelf-life. To further increase shelf-life, the caviar can be frozen or treated with high heat to remove any bacteria. When frozen or pasteurized, malossol caviar can last over a year, but the taste and texture can be negatively affected.
Pressed caviar and semi-preserved caviar is usually stored in vacuum sealed containers as well, having an one year average shelf-life. While pressed caviar needs to be kept cool, semi-preserved caviar's high salt content and other preservatives allow it to remain outside coolers and freezers without spoiling.