Putting the heat on roasts

By Russ Parsons
Los Angeles Times

Tapenade, a black-olive paste, coats this rib roast. For tender meat, roast it at 300 degrees until the meat thermometer registers 125 degrees. Let it rest 10 minutes before serving, during which time internal temperature should reach 135. Los Angeles Times

Preheat the oven, pat the meat dry, rub it or stuff it with whatever ingredients you like, and put it in the oven.

The only tools you need are a roasting pan and rack and a good instant-read thermometer. The only cooking technique required is setting the oven temperature.

Ah, but there's the sticky part.

Beef and pork today contains significantly less fat than in the past. The percentage of fat in the average piece of pork has been cut by a third, and fat in beef fell 27 percent from the early '80s to 1990 and, according to a beef industry spokesman, is "probably well below that now."

Some luxury cuts such as sirloin and tenderloin now meet government standards as "lean" — low in fat and cholesterol. The result has been to reduce the margin of error in roasting. Today if you overcook meat even a little bit, you'll know it immediately.

To unravel this particular puzzle, the Los Angeles Times test kitchen staff searched through hundreds of pages of scientific reports and then cooked about a dozen roasts — pork and beef. We cooked them to medium temperatures and rarer. We used ovens that were blazing and hot, or gentle and slow, and some in between — starting high and finishing low.

Looking at the sliced roasts side by side, you would never guess that the only thing different about their preparation was the oven temperature. And the secret to the most successful — a moist, delicious roast — was a low temperature, both for the finished roast and for the oven in which it's cooked.

Prepared at a lower oven temperature for a slightly longer time, a roast cooked to 125 degrees (normally considered quite rare) came out looking more like a conservative medium-rare. The meat was firm and definitely cooked through, but still juicy and flavorful.

Meat cooked in a hot oven, on the other hand, was slightly raw in the center — even though it had been cooked to the same temperature.

Because anything cooked with liquid present will never get hotter than the boiling point — 212 degrees — braised meat will never brown. That's why you should be sure to pat roasts completely dry before putting them in the oven.

With roasting, grilling and sautéing, dryness is a problem. But it isn't dry air that causes the loss of juiciness, but the effects of the heat. When meat roasts, the protein strands contract and squeeze out the moisture they hold (as we'll see, as much as 25 percent).

When there is fat in the meat — either on the outside of the cut or the fine marbling within the muscle — this isn't such a problem. The fat melts, too, and that makes these cuts seem juicy even if there is less actual moisture in the meat. Today's leaner cuts need gentler handling — but at what temperature?

For the answer, we took three beef and three pork loins of roughly the same sizes and roasted them — one of each at moderately high heat (450 degrees), one of each at moderately low heat (300 degrees) and one of each straddling the fence (450 degrees turned down to 300 after 15 minutes).

When the roasts were done, we removed them from the oven and set them aside for 10 to 15 minutes to rest. This is important because it allows the roast to finish cooking with the residual heat in the meat. The internal temperature will increase from 5 to 15 degrees during the rest. Equally important, it allows the meat's juices, which have been driven to the center by the heat of cooking, to redistribute evenly through the roast.

We cooked the beef to an internal temperature of 125 degrees. After a 10-minute rest, it was at 135, on the rare side of medium-rare — definitely moist and reddish pink, but the muscle fibers were set, not raw.

The pork we cooked to an internal temperature of 145 degrees (rising to 155 after the rest). This is somewhat lower than the current USDA standard of 160 degrees, but well above the minimum for safety. Pork needs to be held at 140 degrees for less than a minute to eliminate any threat of trichinosis.

Here's what we found:

• High-heat roasts: Better crust, tougher meat, less flavor. Roasts cooked at 450 degrees definitely chewy and a little dry in the outside portions and still quite rare in the center. Also, beef lost 25 percent of its weight at high heat.
• Low-heat roasts: More tender and moist. Except for the very outer crust, the meat had better flavor — fuller and meatier. Beef lost only 15 percent of its weight.
• High-heat, then low: Right in the middle; crusting not as good, texture not as tender. Beef lost only 15 percent of its weight.
• Poultry: High-heat roasting is still the best way to cook unstuffed poultry, where the skin provides a fatty cover that crisps and crusts well. Birds also have a thermodynamic advantage in that they are hollow. This provides a tunnel for the hot oven air to circulate through and means a far smaller surface-to-volume ratio. Because of this, birds cook fast enough that at 450 or even 500 degrees, overcooking and toughening aren't a problem.

The right tools

• Instant-read thermometer: One of the most useful and versatile kitchen tools; chefs literally wear them on their sleeves. The thermometers, which cost about $25, come in both digital and clock-type formats and contain sensors that quickly read the temperature of whatever the probe is touching. The range is impressive, from proofing yeast at 100 degrees to heating oil for deep-frying at more than 300 degrees.
• Roasting pan and rack: It's important to roast on a rack so the meat doesn't stew in its own juices. A pan below catches those juices for use in gravy. All manner of racks work, but the best have a V shape or upward-curved sides to keep the roast upright and steady.

Rethinking cooking times

The doneness charts in many cookbooks are out of date because today's roast cuts are so lean. In addition, any danger of trichinosis in pork is eliminated if the meat attains and holds 140 degrees for at least one minute.

Here's an updated chart for medium-rare roasts; for well-done, add 5 degrees:

• Beef: Roast at 300 degrees until internal temperature reaches 125 degrees; allow to sit 15 minutes covered with a loose tent of foil while temperature rises to 135 degrees.
• Pork: Roast at 300 degrees until internal temperature reaches 145 degrees; allow to sit 15 minutes covered with a loose tent of foil while temperature rises to 155 degrees.
• Poultry: Roast at 400-500 degrees until internal temperature reaches 160 degrees; allow to sit 10 minutes covered with a loose tent of foil while temperature rises to 165 degrees.