How to Buy and Cook Prime Rib | The Food Lab

Is there anything more truly beautiful than a perfect prime rib? A deep brown crust crackling with salt and fat, sliced open to reveal a juicy pink center that extends from edge to edge, the faint but distinct funk of dry-aging permeating the room as it's sliced. When you see such a roast in front of you, everything else—the argument you had with your sister over mashed potatoes, the red wine stain on the carpet, the enticingly crisp bowl of roast potatoes, even the plaintive look of the dog staring up with a please sir, can I have a bone? face—disappears as you become lost in a mental vortex of juicy meat, crisp fat, and drippings.

It's the roast that has most often graced my family's holiday table, in various states of increasing deliciousness (I mean, you should see the overcooked, under-browned, dried-up, flavorless things we used to eat!), and the one that most represents the holidays to me. It only makes sense that I've invested considerable time, effort, and BTUs in inching my cooking technique closer and closer to optimal.

Here is the state of affairs in the Prime Rib Universe as they stand today.

The Quick Version: Our Top Recommendations

Buy a bone-in, prime-grade prime rib, preferably dry-aged (or age prime rib yourself). Season well with salt and pepper, and let it rest, uncovered, on a rack in the refrigerator for at least overnight and up to four days. Roast in a 200°F (93°C) oven until it hits 125°F (52°C) at the center (around four to five hours for an average rib roast; your mileage may vary). Remove from the oven, tent lightly with aluminum foil, and let it rest at least 30 minutes and up to one and a half hours. Ten minutes before serving, remove the foil and place it back into an oven preheated to its highest possible setting (500°F+, or 260°C). Roast until well browned and crisp, about 10 minutes. Carve and serve immediately.

Prime Rib, Explained

Q: So what exactly is prime rib?

The prime rib is a tender, flavorful roast cut from the center of the rib section of the steer.

To locate the prime rib, start by cutting your favorite steer neatly down the center from head to tail along the spine. Set aside one half for another use. Place your hand on its back, and feel your way backwards along its vertebrae until you start feeling ribs. Count backwards to the sixth rib (this is called, appropriately enough, "Rib #6"), and cut here.

Now continue counting back until you get to Rib #12 and cut again. Reserve the head section and the tail section for another use, saving only the ribs you just cut out. Saw the ribs off at about 13 to 16 inches down their length, and set aside the belly section. Take off the hide, and what you're left with is the prime rib.

It consists of seven full ribs with a large eye of meat running along their back side. This meat is part of the loin muscle of the steer, the exact same muscle that New York strips, ribeyes, and Delmonicos are cut from. It's also often referred to as a "standing rib roast," because, well, you roast it, it's from the ribs, and it stands up.

Q: Wait a minute—do humans have prime ribs, too?

Absolutely, though ours would most likely not be as tender as a steer's. You see, a steer spends much of its time standing on four legs, eating grass (or grain, as the case may be). Its back muscles do very little work, and, consequently, are very tender. Humans stand upright and do things like bend, lift, jog, and poke fires with sticks. Our backs get more of a workout, producing muscle fibers that are tougher, but probably more flavorful.

Q: So why would I want to eat a little-exercised portion of a steer, and what does marbling mean?

Two reasons: tenderness and fattiness. The loin muscle of a cow is one of the most tender cuts available, beaten out only by the tenderloin (a.k.a. filet mignon, where a chateaubriand comes from). Its advantage over the tenderloin is that it contains a generous amount of fat, both in large swaths around the central eye of meat and, more importantly, within the muscle itself, in a weblike network known as marbling.

Why is this marbling important? Mainly because it lubricates the muscle fibers. At room or fridge temperature, it's a solid fat, but once cooked, it melts, helping muscle fibers slip around each other more easily as you chew, resulting in juicier, more tender meat. Marbling is also important because most of the flavor in red meats comes from the fat. Indeed, studies have been conducted in which tasters fed portions of lean beef and lean lamb were unable to identify them correctly, despite being easily able to do so when given a portion with fat. Fatty beef tastes beefier.

Q: Here's something that's always confused me: Does "prime rib" have anything to do with "prime-grade" beef?

I'm really glad you asked. The answer is no.

The term "prime rib" has existed longer than the USDA's beef-grading system, which classifies beef into various grades according to its potential tenderness and juiciness. It's called prime rib because it's the best part of any given cow. After the USDA began introducing its labeling system denoting quality of beef, and included the label "prime" as the highest quality, things became a little confusing.

These days, it's possible to buy a "prime rib" that is also "prime grade," but it doesn't necessarily have to be so. My local Whole Foods sells "choice grade prime ribs," for example.

A full seven-rib prime rib is a massive hunk of meat, between 20 and 30 pounds. That's too big to fit into my oven in one piece, which is why I, like most people, buy my prime rib in three or four rib sections. These sections have different names depending on where they are cut from.

• Ribs 6 through 9, which come from closer to the cow's shoulder (a.k.a. the chuck), are referred to variously as the "chuck end," the "blade end," or the "second cut." This cut has more separate musculature and more large hunks of fat. Personally, I prefer this end, because I like to eat the fat in a well-roasted piece of beef. If you prefer leaner, more tender beef, then go for...
• Ribs 10 through 12, taken from further back and known as the "loin end," "small end," or "first cut." This has a larger central eye of meat and less fat.

Depending on what part of the country you live in, your butcher will refer to those cuts by various names, but all of them should know which ribs are which. So ask for "ribs 6 through 9" or "10 through 12," and you should be fine.

Beef Grading and Shopping Tips

Q: Can you tell me a bit more about the USDA grading system?

Happy to oblige. Cattle are graded after slaughter according to the degree of marbling, as well as the cow's age.

Starting from the top, there's "prime," which denotes abundant marbling in a cow under 42 months of age. Only about 2% of the beef sold in this country is designated prime, and most of it goes to restaurants and specialty butchers.

Next is "choice," the standard option at high-end supermarkets like Whole Foods, for example. Below that is "select," which is what you'll find in most standard supermarkets, and which accounts for the majority of beef destined for the table. These cows have slight marbling and must be under 30 months of age.

After "select" come terms like "commercial," "utility," "cutter," and "canner," which seem more apt for describing scissors than organic matter.

Q: But prime-graded beef is so expensive/difficult to find. Is it really worth seeking out and paying for?

Good question. I held a blind beef tasting to pit choice-grade beef against prime, cooking both in the exact same manner and to the same temperature (oh, the horrors I put up with in the name of science!). Among the eight tasters present, there was an overwhelming and unanimous preference for the prime-graded beef, though the choice was still quite tasty.

Prime generally costs about 25% more per pound than choice, which is a hefty chunk of change for your standard eight- to 10-pound roast feeding 10 people. Then again, I save my prime rib for the holidays—a special occasion that deserves a special piece of beef.

Q: Is all beef graded?

No! Grading is a strictly voluntary process. Though most meat sold commercially will be labeled, occasionally you'll find meat that isn't. This meat tends to fall into one of two categories. Ultra-premium beef, such as Japanese-style wagyu or Kobe beef, will generally have a marbling and tenderness profile that places it well beyond prime-grade American beef. One hundred percent grass-fed beef will often be sold unlabeled; it tends to be leaner and less marbled than its grain-finished counterparts, so a grade would only hurt its sales. For grass-fed beef, use your eyes instead to judge quality.

Q: How much beef should I buy per person?

In general, you should plan on about one pound of bone-in prime rib per guest, which translates to about one rib section for every two people. Each pound of raw, bone-in prime rib will give you about a half pound of edible cooked meat.

Q: Why does some meat appear dark purple, while other meat appears red? Is it an indication of quality?

It generally has nothing to do with the quality of the meat. It has more to do with exactly when it was cut and how it was stored.

This coloring is caused by the conversion of one of the muscle pigments, myoglobin, and its exposure to oxygen. Immediately after meat is cut, it will be a dark, purplish color—the color of myoglobin. Soon, oxygen will begin to interact with the iron in myoglobin, converting it to oxymyoglobin, which has a bright, cherry-red color. Have you ever noticed how when you cut into a rare steak in an oxygen-rich environment (like your house), it starts out dark, then "blooms" into redness? Now try the same thing in the vacuum of outer space. See the difference? Well, take my word for it: It will not change color as quickly.

The prime rib on the left was freshly trimmed moments before the photograph was taken, while the one on the right was bought from the butcher counter, where it had been sitting, exposed to oxygen, for several hours at least. Even though the bright, cherry-red color is the one we most associate with freshness, freshness really has nothing to do with it.

Eventually, enzymes present in the meat will cause both myoglobin and oxymyoglobin to lose an electron, forming a pigment called metmyoglobin. It's got a dirty brown/gray/green color. While that doesn't necessarily indicate spoilage, it does mean that the beef has been sitting around for a while.

Q: I hear people describe rare meat as "bloody," but is there really blood in it?

Nope! Beef you buy in the supermarket contains little to no blood. Blood contains a very similar pigment, called hemoglobin. But if somebody orders their beef "bloody," what they really want is "beef that has been cooked to a light enough degree that oxymyoglobin has not yet had a chance to break down." There will not be a speck of actual blood in it.

Labeling Terms, Defined

Q: What do "natural," "grass-fed," and "organic" really mean?

Labeling laws in the United States are confusing at the very least, and, in many cases, worthless. Bear in mind that it's also not in the best interest of the vast majority of beef producers to make the labeling any clearer—the less the consumer knows about how meat gets on their table, the better.

There's a bit of confusion surrounding the term "grass-fed." The vast majority of cattle in this country are raised grazing on pasture for most of their lives. It's the last few months of their lives—the "finishing" stage—where labels really come into play.

Here are a few labels you might see in the market, and what they mean:

• Natural means basically nothing. There's no enforcement; there are no rules. It's basically an honor system between the producer and the customer, but no third party checks it.
• Naturally raised, on the other hand, does mean something. As of 2009, the label ensures that the animals are free of growth promotants and antibiotics, except coccidiostats for parasites, and that they were never fed animal by-products.
• Organic beef is certified and inspected by the government, must be fed completely organic feed grains, and must be antibiotic- and hormone-free. The cattle must also have had access to pasture, though, in reality, this "access" could be a single patch of grass on the far side of a large dirt feedlot. Organic cattle are also subject to stricter enforcement of humane treatment. Very recent legislation mandates that at least 30% of their dry-matter intake needs to come from pasture for 120 days out of the year.
• Grass-fed cattle must, at some point in their lives, have been raised on a diet of grass. They do not necessarily receive a 100% grass diet, nor are they necessarily finished on grass. Most "grass-fed" cattle are fed grain for their last few weeks to fatten them. The very definition of "grass" is also up for debate. Many producers want to include young corn stalks under the umbrella of "grass," effectively diluting the meaning of the label.
• One hundred percent grass-fed indicates that the cattle were raised and finished either on pasture or on grass-based feed. As with the "grass-fed" label, the exact definition of "grass" is contentious and seems to vary with each new piece of legislation.

If concern for the animal or the environment is important to you, your best bet is to always ask the butcher or farmer about the steer before purchase. If they can't or refuse to answer questions, it's generally a safe bet to assume the worst. Folks who go above and beyond to provide a decent existence for their farm animals do so at great expense. It's in their interest to let you know about it.

Don't believe everything you read. And don't forget your towel.

Many studies indicate that it is. It's certainly healthier for a cow, a ruminant animal whose digestive system has evolved to break down grass. According to New York University professor Marion Nestle, grass-fed cows tend to have lower levels of E. coli, require fewer antibiotics, and have lower levels of dangerous bacteria in their feces, making them all-in-all safer to consume. They also tend to have higher levels of omega-3 fatty acids (that's the healthy stuff), as well as a higher level of trans conjugated linoleic acids (CLAs).

Q: And what about flavor? Does grass-fed taste better?

It really depends on whom you ask. To the average American palate, the fatty, well-marbled texture of grain-fed beef is the standard, and it's what most steakhouses and fancy hotels hold in the highest regard. But there's certainly something to be said for the generally gamier flavor of 100% grass-fed beef.

On Dry-Aging

Q: How does dry-aging work?

Good question! Dry-aging is the process of storing whole, untrimmed cuts of meat in a very well-controlled environment for several weeks or months to promote desirable changes in the texture and flavor of the meat. Meat is typically dry-aged for between 21 and 60 days, though it can be aged for far longer. Typically, texture changes don't occur until at least 21 days have passed, while flavor changes don't occur until around the 28-day mark.

Note: There have been several articles and TV shows in recent years that have suggested it is possible to dry-age individual steaks. This is patently false. At best, you can dry out the exterior of an individual steak, which makes it easier to brown, but no other flavor or textural changes will occur. True dry-aging requires whole cuts of beef.

A few factors contribute to these flavor and texture changes.

• Moisture loss is often cited as a major factor, but some careful testing has shown that in reality, it has very little to do with the flavor of aged beef.
• Tenderization occurs when enzymes naturally present in the meat act to break down some of the tougher muscle fibers and connective tissues. A well-aged steak should be noticeably more tender than a fresh steak. But is it?
• Flavor change is caused by numerous processes, including enzymatic and bacterial action, along with the oxidation of fat and other fat-like molecules. Properly dry-aged meat will develop deeply beefy, nutty, and almost cheese-like aromas.

Q: Is aged meat really better than fresh meat?

It depends. I had a panel of tasters test meat aged to various degrees and rank them on overall preference, tenderness, and funkiness. Almost everybody who tasted meat that had been aged for a couple of weeks—the period after which some degree of tenderization has occurred, but seriously funky flavor has yet to develop—preferred it to completely fresh meat.

On the other hand, folks were more mixed about meat aged longer than that. Many preferred the more complex, cheese-like flavors that develop in meat aged between 30 and 45 days. Some even liked the ultra-funky flavors developed in 45- to 60-day-old meat. Where you lie on that spectrum is a matter of experience. I personally prefer meat aged to 60 days, though beyond that, it gets a little too strong for me.

Q: Is it possible to dry-age meat at home?

It sure is! Check out our complete guide to dry-aging beef at home for instructions on how to do it.

Bones and Salt

Q: Here's one for you: bone-in or bone-out?

I've always wondered about this one myself, so I ran a series of tests. The idea that many chefs propose is that cooking meat on the bone is always a better idea, as the bone adds lots of flavor. I'm skeptical.

First of all, most of the flavor found in a bone is deep inside, in the marrow. If you've ever tried to make a stock out of just bones, you've found that it's almost tasteless unless the bones are cracked. Second, I've shown numerous times that, as far as flavor penetration goes, there's very little movement of molecules across a piece of meat. Even marinating overnight will get you only a couple millimeters of penetration. What chance does any flavor from the bone have of getting into the meat?

To test this, I cooked four identical roasts. The first was cooked with the bone in. For the second, I removed the bone, but tied it back against the meat while cooking. For the third, I removed the bone and tied it back to the meat with an intervening piece of impermeable heavy-duty aluminum foil. The fourth was cooked completely without the bone.

Tasted side by side, the first three were completely indistinguishable from each other. The fourth, on the other hand, was a little tougher in the region where the bone had been. What does this indicate? Well, first off, it means the flavor-exchange theory is bunk—the completely intact piece of meat tasted exactly the same as the one with the intervening aluminum foil. But it also means that the bone does serve at least one important function: It insulates the meat, slowing its cooking and providing less surface area to lose moisture.

Bottom line: The best way to cook your beef is to detach the bone and tie it back on. You get the same cooking quality of a completely intact roast, with the advantage that once it's cooked, carving is as simple as cutting the string, removing the bones, and slicing.

Q: Does it really matter when I salt my meat?

Absolutely. When you first apply salt to a piece of meat, it sits in dry crystals on the surface (as in the image above), but you'll find that those crystals quite rapidly dissolve (see the image below). Because of a phenomenon known as osmosis, the salt will initially draw liquid out of the meat and onto the surface. By the 25-minute mark, those juices will form distinct droplets on the meat's surface. Meat cooked at this stage will end up with a leathery crust.

Eventually, as we hit the 40-minute mark, the salty meat juices will have begun to react with the muscle fibers themselves, dissolving some of their proteins and causing the structure of the meat to open up, like a sponge. The extracted meat juices soon get reabsorbed, and the salt goes along for the ride. The result is better, more deeply seasoned beef.

Given a few days, unlike a marinade, salt can actually slowly work its way deeper into the meat. I like to heavily salt my prime rib at least four days before roasting, then place it, uncovered, on a rack set in a rimmed baking sheet in the fridge.

And don't forget to put salt on the table as well—after you slice that beef, there'll be a huge expanse of pink meat in the center that needs to be seasoned, too!

Cooking Tips

Q: What's the best way to cook prime rib?

Cooking a prime rib can be as easy as throwing it in a hot oven, closing the door, and taking it out when the timer goes off. But that's not the path to the most tender, most evenly cooked, juiciest results. How do we get there? With a lot of research, a bit of science, and a novel method that flips the standard cooking procedure on its head.

I strongly recommend using a method I developed back when I was working at Cook's Illustrated magazine, called the reverse sear. By starting your roast in a very low-temperature oven and slow-cooking it until it hits close to its final serving temperature, then finishing it with a short blast in a very, very hot oven, you maximize the amount of evenly cooked, pink, juicy meat, while delivering a flavorful crust.

Check out my article on how to cook a perfect prime rib for a demonstration of the science behind it.

Q: So how do I know when my meat is done?

One way and one way only: Use a thermometer. Forget temperature and timing charts—they are wildly inaccurate and can vary depending on the exact shape and size of the roast, how your oven circulates heat, how accurate your oven is, and even how often you peek inside. Forget poking and prodding your meat. Only after hours and hours and hours of experience, working in the same environment over and over, do restaurant cooks get proficient at telling the doneness of meat by touch. It's not practical for a home cook who only occasionally cooks a roast of this size and who buys their meat from varying sources.

A thermometer is the only 100% foolproof, accurate way to gauge doneness in meat. I highly recommend either the Thermapen or the low-cost ThermoPop as your go-to instant-read digital thermometer.

No matter what cooking method or oven temperature you use, as long as the center of your meat never goes above the right temperature, you'll be guaranteed the right results.

Here's what you should shoot for. (These temperatures are a good 10 to 20°F lower than what's given in USDA guides, which tend to overshoot everything.)

• 120°F/49°C (rare): Bright red and slippery on the interior. Abundant intramuscular fat has yet to soften and render.
• 130°F/54°C (medium-rare): The meat has begun to turn pink and is significantly firmer. Juicier, moister, and more tender, and beefier than either rare or medium meat.
• 140°F/60°C (medium): Solid rosy pink and quite firm to the touch. Still moist, but verging on dry. Fat is fully rendered at this stage, delivering plenty of beefy flavor.
• 150°F/66°C (medium-well): Pink, but verging on gray. Moisture level has dropped precipitously. Chewy, fibrous texture. Fat has fully rendered, and has begun to collect outside the steak, carrying away flavor with it.
• 160°F/71°C (well-done): Dry, gray, and lifeless. Moisture loss is up to 18%, and fat has completely rendered. What once was cow, now is dust.

Q: What's this "carryover cooking" that I often hear about?

Carryover cooking is the phenomenon that occurs when you remove a hot piece of meat from the oven. If you've cooked it in a very hot oven (350°F/175°C or higher), the center of the meat may be at, say, 110°F (43°C), while the outer layers could be as hot as 170 or 180°F (77 to 82°C). As the meat rests, some of the heat energy from the outer layers is transferred to the center, causing the center to continue to rise in temperature even after the beef is removed from the oven.

When you're roasting a large piece of beef from start to finish in a hot (350°F+) oven, it's important to remove it when it's a good 15°F lower than the temperature you want to serve it at. Meats roasted at low temperatures (say, 250°F/120°C or lower) will experience very little carryover cooking, as they will tend to cook more evenly from edge to center.

Finishing a roast by blasting it in a 500°F/260°C+ oven for a few minutes to crisp the exterior will not result in any carryover cooking.

Q: What factors determine how the meat browns, and how can I maximize browning?

Browning occurs when proteins and sugars in the meat break down and interact with each other in a complex series of events known as the Maillard reaction. (Note: This is not caramelization. Meat does not caramelize.) To maximize this reaction, you need high temperatures and meat that's free of moisture. This starts with salting and letting the meat rest uncovered in the refrigerator for a few nights. The exterior surface will dry out, giving you a better starting point for browning.

To further improve browning, I like to wait until the very end of cooking to do the browning phase, after the meat is already relatively warm and dry from a slow cook in the oven. With a sear at the end, it takes just a few minutes in a 500°F/260°C+ oven to get the meat to brown.

Q: I've heard that searing meat at a high temperature right at the start of cooking will "lock in juices," resulting in a moister finished product. Is this true?

Nothing could be further from the truth. In my thorough exploration of this very question, I found that meat seared before roasting loses a good 1.68% more juice than meat seared after roasting.

As is often the case, traditional knowledge doesn't stand up to scrutiny.

Q: What is this whole resting business about, and is it really important for my meat?

When meat is fresh out of the oven, there's a significant temperature gradient inside. The hotter areas will tend to have very loose, liquid juices, with a tendency to run out onto the plate as soon as you slice the meat open. When the meat is allowed to rest until it reaches an equilibrium that's still hot, but not too hot, those juices are retained far better, staying in the meat where they belong. Read up more about resting meat here.

A good rule of thumb is to let your meat rest down to 2 to 5°F (1 to 3°C) below its final cooking temperature. So if you're aiming for a rosy-red 120°F (49°C), let the rib cool to 118°F (48°C) before carving.

Q: What about fancy-pants chefs who cook their prime rib sous vide or sear them with various pieces of industrial machinery?

Leave the fancy-pants methods to the fancy pants. In my experience, cooking large roasts—whether prime rib or turkey—in a sous vide water bath certainly guarantees perfectly evenly cooked results, but a lot of the deep, roasted flavor notes that you get from meat roasted in the open air are completely absent. It's also a pain in the butt to try to vacuum-seal an entire prime rib. I much prefer mine done in a low-temperature oven.

As for torching, it looks really cool, but the results are not worth the trouble. Torching before roasting gives you a surface that's nearly burnt in spots and barely browned in others, while torching after roasting doesn't do nearly as good a job as a hot oven or a roasting pan set over a couple of burners does.

Q: My dainty aunt likes her meat rare, but my tempestuous brother prefers his well-done. What's an understanding and generous host to do?

First off, you should wonder how your brother was created out of the same genetic material as you. After that, you should take his portion from the perfectly medium-rare beef, slice it, and either toss it in the microwave for a few minutes or put it back into the oven until it is the desired shade of dry.

Carving, Serving, and Storage

Q: Any good sauce recommendations for that beef?

Our recipe for prime rib with red wine jus comes with a sauce built right in. If, instead, you're using our standard recipe for perfect prime rib, you might want to make a sauce to go with it. Horseradish cream is super simple and a classic pairing. Chimichurri is one of my personal favorites. You can also make a simple Béarnaise sauce. After forming the sauce, stir in some chopped fresh tarragon. Delicious!

Q: What would you serve on the side with prime rib?

Potatoes are a classic pairing, and any one of these recipes would do, though I'm partial to my hasselback potato gratin or my crispy smashed potatoes. With such a heavy meal on the table, I like to keep the rest simple, with a glass of good wine and a simple salad tossed with a perfect vinaigrette.

Q: What's the best way to store leftovers?

For short-term storage, your best bet is to just tightly wrap the leftovers in plastic and keep them in the fridge. They'll last for around three days, after which you should start checking for spoilage. Bear in mind that rare or medium-rare meat may turn brownish (remember myoglobin?) in the fridge. This isn't necessarily a sign of spoilage. Just follow your nose!

For longer-term storage of larger pieces of either cooked or uncooked meat, you'll want to freeze it. If you've got a vacuum sealer, use it. Air is the enemy of frozen food, causing it to dry out in an irreversible process known as freezer burn. If you don't have a vacuum sealer, wrap the meat tightly in foil (air can actually flow through plastic wrap, albeit quite slowly), then a few layers of plastic wrap, and place it in the freezer. The plastic wrap helps keep the foil tight against the surface of the meat, while the foil prevents air from coming in contact with it.

Let your meat defrost in the refrigerator. This can take a couple days for larger cuts of meat.

Q: What's the best way to reheat prime rib?

If you are wise, you will have been slicing meat to order, leaving you with a large chunk of leftovers rather than many thin slices. The best way to reheat a large chunk of meat is to treat it as you would a steak (which, after all, it is): Warm it in a low oven to the desired internal temperature, then sear it in a hot skillet to crisp up and brown the exterior. Alternatively, the microwave is surprisingly effective. Just don't let the meat go above the temperature you initially cooked it to.

If you've already sliced your steak, your best options are sandwiches and salads. Still delicious!

Read More

• Roasted and Reverse Seared Prime Rib
• Perfect Prime Rib With Red Wine Jus
• Koji Prime Rib