Real Food Encyclopedia | Oysters

Jonathan Swift wrote that “It was a brave man who first ate an oyster,” and it’s true that each of us who have looked upon the slimy, grayish, watery bivalves and screwed up the courage to slurp one down is an adventurous sort. The reward is a briny and delicious treat that reflects its “merroir,” or the taste of the waters where it has lived its life. For the most part, oysters are farmed these days, and most of oyster farms are sustainable. If done right, rather than polluting their environment with their production, oysters can even act as filters for the waters they grow in.

True oysters (as opposed to pearl or other varieties) belong to the Ostreidae family, which includes the genera Ostrea, Crassostrea, Ostreloa and Saccostrea. Like clams, mussels and scallops, they are bivalves, or aquatic mollusks with hinged shells. They’re found throughout the world’s oceans, usually growing in clumps, or reefs, in shallow coastal waters. They are filter feeders (eating mostly phytoplankton, but in the process, filtering and cycling nutrients in the water) and provide habitat for other fish.

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What to look for when buying oysters

First, look for oysters with shells that are not broken. If one is open, tap it; if it doesn’t close, toss it. Beyond that, what to look for depends on what type of oyster you like: briny, creamy, sweet, metallic, or earthy.

There are some great guides out there, including those from author Rowan Jacobsen  — this one urges you to figure out your “type” and choose accordingly. Jacobsen’s book, “The Essential Oyster” is a deep dive on the wide array of oysters available, including tasting notes on each.

Food & Wine has recommendations for reputable online ordering companies here.

Sustainability of oysters

As seafood goes, oysters are among the few species one can ingest without guilt. Overall, they are good for the environment and provide a good alternative to land-based animal protein, and as bivalves, they help cycle nutrients in the water they live in, cutting down on pollution. Adult oysters filter 2.5 gallons of water an hour, or more than 50 gallons per day. Also, oyster reefs help protect coastal areas from flooding and erosion.

Seasonality

As the old adage goes, it’s best not to eat oysters during months without any “R”s in them — in other words, summer. As mentioned in the nutrition section below, certain dangerous bacteria thrive in warmer weather, and before modern technologies like refrigerated trucks and chilled tanks, summertime oysters were more dangerous.

Oysters also usually taste better in winter, as author Rowan Jacobsen explains in our podcast episode about oysters: “This is the time of year when they are …most delicious, they’re full of food, they’re plump, they’re sweet. They also kind of sweeten themselves with amino acids that help them, not freeze, right? Sugars. They create these compounds that are kind of like antifreeze compounds are naturally sweet. So a winter oyster is a really good oyster.”

Geography

Food oysters can grow pearls inside but usually don’t — pearl oysters are a different species, but it’s likely that oyster farming techniques developed alongside pearl farming.

There are a few different methods of cultivating oysters. All include the same early stage, where oysters grow loose to the size of “spat,” at which point they are ready to attach themselves to some form of substrate, referred to as a “cultch,” or in some cases, are allowed to grow a little larger, to be used as “seed.” This is where farmers come in and methods vary; one is to distribute seed or spat along existing oyster beds, another is to raise them in bags or cages held off the sea floor and the third to raise them in a specially prepared tank optimized for oyster production.

Ninety-five percent of the world’s oysters are farmed. China leads the world’s production, followed by Korea, Japan and the U.S. The U.S. consumes about 60 percent of the world’s oysters.

Eating Oysters

Storing

Fresh oysters will keep in the fridge a few days, provided they aren’t sealed in plastic, or you’ll suffocate them. Once cooked, anything uneaten should go right back to the refrigerator.

Cooking

Probably the most intimidating part of dealing with oysters is shucking them. Their tight, craggy shells can be tricky to open. Using the right knife and the right technique is key. Check out Molly Watson’s clear oyster shucking instructions.

Eat oysters raw or fried, grilled, in oyster stew, in oyster stuffing, oysters Rockefeller, oyster sliders, you name it. Raw oysters can be great with just a squeeze of lemon. Beginner eaters might do well to add a splash of mignonette. Oyster purists advise against dunking them in cocktail sauce, which obscures their flavor. To dig into some of the old classic cooked oyster recipes, you can peruse M.F.K Fisher’s book “Consider the Oyster.”

To be sure you’re eating them as safely as possible, discard any broken or chipped shells. If an oyster is slightly open, tap it with your fingernail and if it doesn’t close itself, toss it.

Nutrition

Oysters are really good for you — rich in protein, phosphorus, iodine, calcium, iron, and Vitamins A, B complex and C.

In a 2005 meeting of the American Chemical Society, scientists announced findings that raw oysters really do have aphrodisiac qualities, and that the amino acids that lead to higher levels of sex hormones is highest in the spring.

Eating raw oysters is not without risk. A marine bacteria called Vibrio vulnificus occurs naturally, especially in low-saline areas like bays and estuaries, and is most common during warm summer months; it has been becoming slightly more common, thanks to rising temperatures, and in the summer of 2023 a few people died from the disease. The FDA recommends cooking oysters thoroughly to prevent getting sick. Others recommend buying ousters from trusted sources.