Oysters are the name given to a family of marine mollusks. Their different genera serve people on the one hand for pearl cultivation, on the other hand as food. Eating oysters is considered gourmet cuisine in Europe and the United States. They are very nutritious and are considered an aphrodisiac. The most important oyster species for food purposes is the Pacific rock oyster.
Here’s what you should know about oysters
Oysters are the name given to a family of marine mollusks. They are highly nutritious and considered an aphrodisiac. In European gourmet cuisine, the oyster is eaten raw and fresh. The prerequisite is a tightly closed shell until consumption. In it, the mussel stores seawater, which it needs to survive. The oyster taste is therefore salty and characterized by the flavors of the sea. Lemon or vinaigrette are typical serving additions and partially neutralize the salt content. The mussel meat is very protein-rich and has a nutty aroma of its own. This comes into its own when the oyster is not swallowed immediately, but is still chewed a little in the mouth. Oysters can also be boiled, fried and grilled. In North America, a diverse recipe culture has developed in this regard. In Asian cuisine, oysters are generally cooked. It does not attach any gourmet significance to them. Oysters have existed for 250 million years. They have many natural predators. For their protection, they have therefore developed very thick shell valves. The vulnerable mollusk forms them on its belly and back. The dorsal valve is flatter than the ventral valve. A mechanical joint connects the shell valves and keeps them open a crack. The mussel has neither brain nor eyes. 40% of its body mass is muscle. When it tenses its muscles, the shell valves close airtight and store small amounts of seawater inside. Using this technique, oysters can survive for about 14 days on dry surfaces. The muscular strength of the small mollusks is so great that humans cannot open the shells under their own power. They can only do so by the leverage of a tool – usually an oyster knife. Oysters do not have a shell foot to move around. That is why they remain in the same location throughout their lives. They prefer to live in coastal waters and like to live near rivers. There, seawater contains more nutrients than at the bottom of the sea. Oysters filter 240 liters of water per day and feed on microalgae. Due to human consumption and marine pollution, wild oysters have been severely depleted. 96% of all oysters consumed come from aquaculture. The Pacific rock oyster accounts for 93.7%. The largest part comes from China. In Europe, this oyster species is mostly sold as “Fines de Claire”. The American oyster accounts for 5.1% of the annual production. The share of European oysters is only 0.2%. They are named after their cultivars: Bélon in France, for example, and Colchester in Great Britain.
Importance for health
The health effects of edible oysters are many. They have a sleep and appetite stimulating effect. They are extremely low in calories and are very suitable for dietary meals. 1 – 2 % of the shellfish flesh is composed of vitamins and minerals. Therefore, oysters provide an optimal supply of trace elements. When eaten raw, these vital substances are available to the body’s functions without restriction. Oysters contain a high proportion of zinc. This chemical element supports the formation of the male sex hormone testosterone. Therefore, oysters are believed to have a desire-enhancing effect and to increase the duration of erections. Oyster shell contains organic sulfur compounds with anti-inflammatory effects. Ground oyster shells are used in empirical medicine to relieve rheumatic diseases and pain.
Ingredients and nutritional values
Oysters are 83-86% water, 9-10% protein and 4% carbohydrate. They contain a lot of calcium and magnesium, plus zinc and iron, as well as iodine and phosphorus. They provide the body with vitamins A, B1, B2, B12, as well as nicotinamide, folic acid and biotin. 100 g of oyster meat contain about 65 – 75 kcal.
Intolerances and allergies
Oysters should only be purchased and eaten at locations that are subject to regular food and health inspection. Health risks exist when eating oysters of unclear origin.Then there is no guarantee that the oysters do not contain parasites or harmful bacteria. Oysters are also problematic if they come from a marine environment with toxic algae or an algal bloom (so-called red tide). The toxic substances accumulate in the shellfish flesh. Eating such oysters is highly toxic. To protect oneself from health risks, it is imperative to pay attention to certified origin. Eating dead oysters is also highly toxic. The decomposition process releases dangerous shellfish toxins.
Shopping and kitchen tips
The freshest and best quality oysters are available directly from oyster farmers in coastal regions — accessible to most consumers only during vacations. In everyday life, fishmongers, supermarkets and Internet ordering services are the alternative. Those who want to prepare hot meals and cook or fry the oysters can choose frozen oysters without hesitation. When buying fresh oysters, their condition can best be checked at the local fishmonger or supermarket. Oysters would never open their shells outside of water. Only a dead oyster will no longer tense its muscles and therefore exhibit an open shell. If a mussel with open shell valves can be discovered in the assortment, it is better to refrain from buying it altogether. This also applies to oysters with broken or damaged shells. Care should also be taken to ensure that the oysters are lying in the display with the rounded belly side down and have not been thrown around wildly. Sellers should generally be asked when the oysters were fished. A professional retailer will be happy to provide information about this at any time out of responsibility for customer health. For internet orders, delivery should be made within 24 hours. Ideally, oysters should be packed in Styrofoam boxes with cold packs. It is best to consume them immediately. If necessary, oysters can be stored for 3 – 4 days in the refrigerator at temperatures between 5 – 10 °C. To do this, layer the oysters in a watertight container – belly down. Place a cloth over them and store them separately from other food. Before preparation, carefully clean the shells under running water with a brush.
Preparation tips
To eat raw oysters, the shell must be opened with an oyster knife. This poses a high risk of injury. Be sure to wrap the top of the shell in a thick towel or put on a special protective glove. Insert the knife into the backside shell joint, turn the knife clockwise, then the joint will break. Then run the knife edge directly along the top shell to separate the top shell from the oyster muscle. Remove shell and separate the belly shell from the muscle meat. They can be eaten unseasoned or dressed to taste with lemon juice, parsley, onions. The separated oyster meat can be breaded and deep fried or fried in a pan. With the shells they can be boiled or grilled. Only mussels whose shells open after 5 – 10 minutes and from which (when grilled) the water stored inside foams in fine bubbles from the mussel crevice should be eaten.
