According to the Gourmet Cookbook, “Most mussels sold today are cultivated, meaning that they’re farmed on suspended ropes or in beds on the ocean floor and closely monitored. After harvest, they’re carefully cleaned and graded.” The result of cultivation is that mussels, once a nuisance to clean and debeard (remove the wiry thread the mussel uses to anchor itself) are now meatier, free of grit, and require only a light scrub before cooking. Since mussels are filter feeders (they feed on plankton in the water around them), they are sensitive to the effects of water contamination; Marine biologists have actually used mussels to evaluate water quality. Cultivation results in water that is closely monitored for contamination.
The mussels most commonly found on the East Coast are the cultivated blue ones from Prince Edward Island, but sometimes green New Zealand mussels appear in the shops, and, on rare occasions, Mediterranean mussels, cultivated on the West Coast, make their way across country. Back to Gourmet’s instructions: “The key to great mussels is freshness – you want them alive. It’s best if they’re no more than four days old. Proper handling is also crucial. They should be stored at the grocery in or on ice. Select those with closed shells and take a sniff –they should smell pleasantly briny. Once home, drain off any liquid before refrigerating them in a bowl, covered with a wet towel. Don’t worry if some open their shells while in the fridge. When ready to cook them – the same day is best – tap those with open shells and discard any that don’t close by themselves.”
Clean mussels by scrubbing them with a brush under cold water and scraping off any barnacles with a knife. Discard any with cracked or broken shells. If the beard (byssus) is still attached, remove it by cutting it off with a knife. To steam 1-1/2 to 4-1/2 pounds of mussels, put 1 cup of liquid – water or a mix of water and white wine or beer (not dark) – into a 4 to 6 quart pot. Bring the liquid to a boil over high heat, then dump in the mussels and cover the pot. Reduce the heat to moderate and cook the mussels, stirring occasionally, until they open wide. This will take 3 to 6 minutes, but check frequently after 3 minutes, and scoop out the mussels as they open with a slotted spoon. Discard any that remain closed after 6 minutes, and save the flavor-packed cooking liquid if desired.