“Before you make those delicious pan-seared scallops, you need to buy the scallops. Unfortunately, that’s not always so simple.

Like shrimp, fresh scallops can be sold under a bewildering array of names — such as “bay” scallops, “sea” scallops and “jumbo” scallops — that don’t necessarily indicate a specific size or weight. And then there’s the mysterious “diver” scallop. What do all these descriptions mean?

Scallops Sizes
Retailers should describe scallop sizes by a range of numbers indicating how many of them there would be in a pound. Designating scallops as “20/30” would mean that it would take between 20 and 30 of them to make up a pound. The smaller the number is, the larger (by weight) the scallops are.

You may also see size designations that look like “U/15” or “U/10.” In these cases, the “U” stands for “under,” indicating that it would take fewer than 10 (or 15) of these to make up a pound. U/10 scallops would be the biggest ones available.

Bay Scallops
Bay scallops are among the smallest of the scallops, corresponding to 70/120 using the numerical scale described above — meaning that there would be between 70 and 120 meats per pound of scallops. Bay scallops are particularly sweet and delicate, but not well suited for pan searing.

Alternate names:
Cape scallops
Nantucket scallops
China scallops
Calico scallops
Queen scallops

Sea Scallops
At the opposite end of the size spectrum, sea scallops are the big boys — in the range of 10/40 per pound or even bigger (U/15 or U/10, for instance). Reaching 1½ to 2 inches in diameter, they can be pan seared much like a filet mignon — with high heat producing a crispy outer crust, while leaving the center tender and medium to medium-rare.

Alternate names:
King scallops
Great scallops
Diver scallops
Alaskan scallops
Jumbo scallops

Diver Scallops
Most scallops are harvested by boats dragging chain nets across the ocean floor. Diver scallops are harvested by divers who jump into the water and collect them by hand. The term “diver” does not itself imply a size, but these divers generally pick the largest scallops they can find, so diver scallops tend to be in the 10/30 range.

Aficionados say diver scallops are more ecological because the divers only pick the bigger, more mature scallops, while leaving the younger ones, which allows the population to replenish; whereas dragging with chains is indiscriminate and sweeps up other shellfish besides just scallops.

Fresh vs. Frozen Scallops
Just because a scallop has never been frozen is no guarantee that it’s been properly handled on its journey from fishing boat to supermarket. Choosing between frozen and fresh depends on what’s available. If you live near the coast and have a reputable seafood purveyor, and plan to use the scallops the same day you buy them, fresh might be best. But a good IQF (individually quick frozen) scallop might be superior to a “fresh” supermarket scallop that’s five days old.
Thaw frozen scallops overnight in the fridge. Don’t use a microwave and don’t thaw them at room temperature. In a pinch, you can defrost frozen scallops by sealing them in a plastic zipper bag and running cold (not warm or hot) water over them.

Wet vs. Dry Packed Scallops
Scallops are often soaked in a phosphate solution that whitens them and makes them absorb more liquid, increasing their weight by as much as 30 percent. So you’re paying $15 to $20 (or more) per pound for water.

Also, that phosphate solution is a common ingredient in soaps and detergents, and, not surprisingly, has a distinctly soap-like flavor. When you cook these scallops, all that extra liquid drains out and into the pan, so instead of searing them, you end up steaming them in something closely resembling soapy water.
If you want to avoid all that, look for scallops labeled “chemical free” or “dry packed.”

Source:  wwwthespruce, by Danilo Alfaro