This month's Processing column continues with "How is it processed?" theme, focusing on caviar. Caviar comes from the Persian word khaviar, which means "egg cup". The traditional caviar is the wild sturgeon bottarga raised in the Caspian and Black Seas and has historically been called “black gold”; it is collected by the beluga, osetra and sevruga sturgeon. Many countries include eggs of other sturgeon species, as well as other fish, such as salmon, trout, steelhead, carp, and whitefish, under the caviar label. According to the rulings of the US Food and Drug Administration, however, the real caviar only comes from the sturgeon.
Caviar was prized by Byzantine Greek aristocrats, who traded with Russia as early as the 10th century. Beluga caviar from the Caspian Sea is the most expensive variety of caviar, followed by osetra caviar. Its popularity has led to the depletion of wild stocks due to overfishing. In 2005, the U.S. Fish and Wildlife Service banned the import of Caspian and Black Sea beluga caviar to protect the endangered beluga sturgeon. This was followed in 2008 and 2011 by Russia's suspension of wild caviar production to replenish wild stocks. In recent years there has been a dramatic increase in the production of “sustainable” caviar from aquaculture farms.
The global caviar market was valued at $ 276.2 million in 2018 (Grand View Research 2019). Osetra caviar is popular with high-income consumers and its market value in 2018 was $ 72.1 million (Grand View Research 2019). It is available in a wide range of colors, from black to blue to yellow to green. A teaspoon of caviar can cost more than a family meal at some restaurants.
If the fish are stressed, they will reabsorb the eggs and will have to return to the growth chambers for another year or two to produce them again.
Sevruga caviar, known for its flavor and texture, accounted for around 25% of global revenue in 2018 (Grand View Research 2019). In recent years, cheap caviar has become widely popular on the market and is easily consumed by novice connoisseurs and prized for its less fishy taste and darker color. The breakdown of sales by caviar form shows that freshly caught caviar held the largest market share in 2018, but interestingly, dried caviar is the fastest growing form and is expected to expand at a growth rate. compound annual (CAGR) of 9.1% from 2019 to 2025. The markets for preserved and frozen caviar are projected to increase at a CAGR of 8.4% for the same period of time (Grand View Research 2019).
According to the Washington Post, China exported more than 130 tons of caviar in 2017, while the United States produced just under 16 tons. In the same year, the United States imported Chinese caviar worth $ 7 million, five times the amount imported in 2012. At the same time, wholesale prices dropped by more than 50% (Reiley 2019). The Washington Post also reported that, according to the Food and Agriculture Organization of the United Nations, the import price went from $ 850,000 per ton in January 2012 to $ 350,000 per ton in November 2018.
Caviar has numerous positive health benefits. It is rich in protein, omega-3 fatty acids and selenium. One tablespoon of caviar provides adults' daily vitamin B12 requirement. High-quality caviar is known for its firm texture and aromatic qualities, which include a creamy and buttery taste, along with a delicate fishy finish.
Harvesting and processing
Commercial cultivation and harvesting of caviar have become popular due to overfishing in the wild. All over the world, sturgeon is bred to produce caviar using aquaculture. Young fish require constant feeding and are continuously fed high protein pellets throughout the day and night. As the fish grow, the frequency of feeding decreases. Bacteria are added to the culture tanks to remove toxic metabolites and the tanks are monitored regularly to ensure optimal fish growth. After several months, the fish are moved to larger tanks. The water from these tanks is continuously circulated to introduce oxygen and remove the carbon dioxide produced by the fish. Solid waste is removed from the tanks by filtering the water through screens. Additionally, water circulates through pieces of plastic that contain filter bacteria and molasses is added to reservoirs to feed those bacteria.
It takes seven to 10 years for the fish to be ready to be harvested for its eggs. Eggs can represent 15% to 18% of the weight of the sturgeon. At this stage, the fish are typically at least one meter long. Interestingly, there is no visual way to externally determine whether a fish is male or female. For this reason, high frequency ultrasound is needed to determine not only the sex of the fish but also the development of the eggs within the fish. Various methods are used to sedate the fish. These include exposure to carbon dioxide or sedatives, as well as sedation via a low electric current. Once the fish have been sedated, high-frequency ultrasound is used to evaluate the sturgeon's ovaries, or sacks in a row, and to evaluate egg production in each fish, one at a time.
Person in a laboratory setting
Caviar processing requires gentle handling. © Paolo_Toffanin / E + / Getty Images
Small biopsies are also performed to visually observe the quality of the egg, including color and size. The color of the eggs in each fish varies and there is no way to predict this. For example, "royal" caviar is gold and is found in only one sturgeon in 1,000 osetra. When ready for harvesting, the sturgeon will contain tens of thousands of eggs. By the age of seven, only about 10% to 20% of the fish is typically ready for harvest. Fish that are not yet ready are returned to the tank for another year of growth.
During the next processing step, the fish are purged into clean water tanks. This step is important for eliminating unpleasant flavors. It is also important that the fish are not stressed at this or any stage of their growth. If the fish are stressed, they will reabsorb the eggs and will have to return to the growth chambers for another year or two to produce them again.
It is at this stage that processing methods overlap for fresh and farmed commercial caviar. The fish are quickly stunned and the two ovaries are removed by a process called “stripping” which extracts the caviar through a small incision in the wall of the fish. Alternatively, the caviar can be extracted by doing a caesarean section, which can then be stitched up, allowing the female to continue producing eggs. The third process for egg removal is to massage the eggs out of the fish.
The very fragile eggs are then refrigerated and gently removed from the membrane by hand by rubbing the eggs against a mesh sieve. The tissue is then removed for composting. The eggs are then rinsed repeatedly with cold water to wash away the impurities, broken eggs and membrane residues. Further removal of crushed eggs and impurities is achieved by manual removal, using tweezers. The pure eggs are then poured into a fine mesh colander to remove the water.
The caviar is then carefully weighed and salted. Very fine salt is used in the process and its addition is crucial for optimal flavor and shelf life of the caviar. The lightly salted caviar is called "malossol" and has a salt content of less than 5%. Most high-quality caviar contains less than 3% salt. Caviar with a salt content of up to 8% is called salted caviar or semi-preserved caviar, and its taste is less fresh. By adding more than 10% salt, the product takes the name of "payusnaya" and forms a jelly-like cake that can be kept for three months.
The caviar is then cooled to allow it to absorb the salt from six minutes to several hours, after which it is drained again using a colander to remove the water. After draining it, it dries further by dabbing it thoroughly with a towel.
Now the caviar is ready to be packaged. Lacquer-coated cans are commonly used and are filled by hand and gently pressed to remove air. Air causes oxidation and deterioration during storage. The jars are then hermetically sealed.
Caviar is typically aged for three months. Aging is crucial for the flavor of the final product and for the caviar to develop subtle fragrance notes. Sometimes a longer aging is used. Caviar is perishable and requires refrigerated storage. Fresh caviar can be stored for two to four weeks. Caviar can also be pasteurized to extend shelf life and allow storage times of up to one year at room temperature. Pasteurization is known to reduce the quality in terms of texture and flavor of the final product, but improve food safety. Other methods of storing caviar include freezing and drying, both of which extend the shelf life.
Advances and innovations
The biggest area of innovation in terms of caviar in recent years has been the development of imitation of vegetable caviar, which is typically made from seaweed and can be enjoyed by vegetarians. The flavor and color of the final product mimics those of fresh caviar. It also lacks the cholesterol that is present in fresh caviar.
Another area of innovation for caviar is its use in cosmetics and health supplements. This area is growing rapidly.