What Does Prime Beef Mean and Where Does Prime Rib Come From?

USDA Prime is indeed the finest and most expensive grade of beef.

But we have all at one time or another been subjected to a $5.95 (salad bar included) slab of tough, dry “prime rib” rimmed with vulcanized-rubber fat that clearly deserved to be stamped “USDA Inedible.” Is there some misrepresentation going on here?

Not necessarily. It’s true that in almost any context, the word prime implies first or top quality. But in this case it has nothing to do with quality: It refers only to the cut: where in the animal it came from. A prime rib roast can be of any USDA quality grade at all.

Before they are butchered, the USDA grades beef carcasses into eight quality categories, based on such characteristics as maturity, texture, color and fat distribution, characteristics that result in tenderness, juiciness and flavor on the plate.

In descending order of desirability, they are Prime, Choice, Select, Standard, Commercial, Utility, Cutter, and Canner. (Select used to be called Good until 1987.)

When a carcass is butchered, regardless of its USDA grade, it is first divided into eight “primal” cuts: chuck, rib, short loin, sirloin, round, brisket and shank, short plate, and flank. The primal rib cut consists of rib numbers six to twelve of the steer’s thirteen ribs.

After the tips of the ribs (the short ribs) are chopped off, what remains is what in butcherese shorthand is known as “prime rib.” Again, the name has nothing at all to do with the USDA Prime quality grade, so don’t be enticed by the words on the menu.

Judge the roast’s probable quality by the quality of the restaurant.