Like all shellfish and food from the sea, the oyster has been eaten by humans for as long as they have existed. But the Egyptians and Hebrews considered it impure and did not include it in their diets.
The Ancient Greeks were fond of oysters, and their shells, ostrakon, were used to vote for the banishment of undesirable people. The word ostracism comes from this.
They knew how to farm them. The Romans followed and enjoyed them for centuries. .They were delighted to discover that oysters abounded on the coasts of Gaul during their conquest.
Oysters were popular in the Middle Ages, and they could be found "in the shells" and "shelled", sold by weight without their shell. They would be greatly prized on people's dinner tables during the Renaissance. Later, King Louis XIV loved them, but his prudent doctor advised him to only eat them cooked, either grilled in their shell or fried. Perhaps because of their reputation of being an aphrodisiac, oysters were eaten en masse everywhere in the 18th century, and oyster beds began to be depleted both in Europe and in the Americas. The arrival of the railways in the 19th century made their transport easy, which did not help. It was at that time that oyster farming came into its own on both sides of the Atlantic.
Oysters were for a long time eaten cooked, which was normal, given their delicate nature.
The leading oyster-producing nations are now China, Japan, the United States, Korea, and France.
Whatever its size or origin, an oyster should always be well closed, or if it a little open, it must close immediately when touched. An open oyster is dead and must be disposed of.
When opened, an oyster should be covered in its liquor. It will draw back when touched with the tip of a knife and give off a good sea smell. A dry oyster and/or one with a suspicious smell should be thrown away immediately.
All boxes of oysters bear a health label, indicating their origin and packaging date.
The quality of oysters vary depending on how they are farmed or the region they come from.
The larvae are collected in different ways and attached to supports. These "spats" grow for some 18 months. The oysters, by this time completely formed, are taken to oyster beds for the affinage, or "finishing", for a certain time. These are mostly located in the open seas.
In the Marennes-Oléron region, affinage takes place in clay basins, or claire ponds, usually in abandoned salt marshes. Claire oysters are finished for several days. Fines de claires are finished for 1–2 months at a rate of 20–40 oysters per square meter. Spéciales de claires are finished for 2 months at a rate of 10 oysters per square meter. Spéciales pousse en claire are finished for 4 months with 5 oysters per square meter. Their green color is due to a microscopic algae, blue navicula, that they absorb during this time.
In the Étang de Thau area, Bouzigues oysters are farmed on completely submerged "tables" for 8–11 months using a traditional method.
Prestige oyster-growing regions exist in each country: Whitstable, Helford, and Colchester in the United Kingdom; Blue Point and Cape Cod in the United States; Caraquet and Malpèque in Canada.
Triploid oysters are distinguished by their "beak" at the hinge, which points downwards.
Oysters in Europe are classified by weight, known as caliber. This definition is not the same for concave oysters and flat oysters.
Concave oysters: the categories reflect the weight of a single oyster.
. No. 0: > 150 g
. No. 1: 111–150 g
. No. 2: 86–110 g
. No. 3: 66–85 g
. No. 4: 46–65 g
. No. 5: 30-45 g
Flat oysters: these categories depend on the weight for 100 oysters.
. Category 000: 100 oysters = 10–12 kg
. Category 00: 100 oysters = 9–10 kg
. Category 0: 100 oysters = 8 kg
. Categories 1-6: = 7, 6, 5, 4, 3, and 2 kg, respectively.
Elsewhere, oysters are usually calibrated according to the size of their shell. In Canada and the United States, cocktail oysters are smaller than 76 mm.
Oysters are sold in boxes and by the dozen at fish stores.
They are also sold without the shell, frozen (without shell), and smoked (canned).
Oysters are eaten raw, possibly seasoned with a little lemon juice or shallot vinegar, something purists reject because this acidity ruins their original flavor.
Escoffier served them in different ways: à l'Américaine, à l'Anglaise (broiled covered with bacon slices), au gratin, Maréchal (fried in a light batter), Mornay etc.…
It is just possible that the famous recipe for Oysters Rockefeller was inspired by Escoffier's Oysters à la Florentine: the poached oysters are placed in their shell lined with a bed of spinach cooked in butter, then covered with a Mornay sauce and glazed.
Oyster sauce is a popularly used condiment in Chinese cooking.
Oysters can remain in their box in a cool place at between 5 and 15ºC for up to one week.
If they are sold in bulk, their shell should be laid with the concave side face down, covered with a damp cloth and a weight, at between 5 and 15ºC.
In any case, it is better to use them as quickly as possible.
Oysters are high in minerals of all kinds, B vitamins, and protein. They barely contain any fat, even spawny oysters, but they have a small amount of carbohydrate.
They are reputed to be an aphrodisiac, but this has never been verified scientifically. However, this belief dates back a very long time – reinforced by Casanova, who easily ate several dozen before going out to find a beautiful woman – leading one to think that perhaps their zinc content is the most important thing. This mineral contributes to the production of testosterone, essential for a good libido, but the absorption of zinc does not have an immediate effect.
Numerous species of oysters exist around the world, divided into two main categories: flat oysters, with the scientific name of Ostrea, and the concave oyster, Crassostrea.
The most common varieties are:
. European flat oyster (Ostrea edulis), known as belon in Brittany, and gravette in the Arcachon Bay area.
It is farmed in other parts of the world. The pied-de-cheval oyster is very large (300 g on average). It contains a lot of iodine.
. Pacific or Japanese oyster (Crassostrea gigas)
Native to the northwest Pacific Ocean, it is the most widely farmed oyster in the world. In France, this species has replaced the Portuguese oyster, which accounted for the bulk of production in France until the 1970s, when it was decimated by a disease.
. Huître américaine (Crassostrea virginica): farmed in the United States and Canada.
. Common rock oyster (Crassostrea margaritacea): it is found in Australia, South Africa, and Madagascar.
. New Zealand oyster (Ostrea sinuata or luteria): flat.
The oyster season traditionally fell in the months ending in r. During the remaining months – May, June, July, and August – they are spawny (filled with fertilized eggs), which they release when the water temperature is approximately 18ºC.
. Triploid oysters, also known as "four seasons oysters"
This is an oyster that has been genetically modified (by chromosome manipulation) to make it sterile, and therefore saleable throughout the year. It also develops faster than other, diploid, oysters.