The road to the perfect roast

March 08, 1995|By Russ Parsons | Russ Parsons,Los Angeles Times

Browned and meaty, yet pink and tangy. Crusty outside, yet buttery inside. Firm, yet tender. Juicy, but not stringy. The art of roasting is the art of compromise.

It is one of the oldest forms of cookery, and it is one of the grandest. For most cooks, it is also one fraught with concern.

"We can learn to be cooks, but we must be born knowing how to roast," wrote the French culinary philosopher Brillat-Savarin in "The Physiology of Taste" in 1825. But that was before the invention of the instant-read thermometer. If it's a roaster you want to be, there can be no better way to spend $10 than to run down to the grocery store and pluck one off the housewares shelf.

Different from the traditional meat thermometer -- those notoriously inaccurate things that stay in the meat throughout the cooking process -- an instant-read thermometer gives you a quick and exact reading. Just plunge it into the roast at its thickest part (being careful to stay away from the bone), and within a minute you know where you are.

In roasting, temperature is all.

In a study called "Flavor, Color, and Other Characteristics of Beef Longissimus Muscle Heated to Seven Internal Temperatures," scientists at Kansas State University found that "beef flavor components and juiciness change most from 130 degrees to 150 degrees, then little change takes place until meat is heated to temperatures between 175 and 185 degrees, when browned and mouth-filling blend components increase and juiciness decreases."

In other words, these guys roasted beef loin from very rare to very well-done. What they found was that the peak temperature for flavor and juiciness was between very rare and medium-rare (on the USDA scale).

A group from the University of Missouri college of agriculture did the same thing with pork. Their findings? "The optimum endpoint temperature for fresh pork roasts should be at least 160 degrees and should not exceed 170 degrees."

Though studies on lamb are harder to come by, one 35-year-old study found that legs of lamb "have an odour and taste more characteristic of lamb" if cooked to 150 degrees than to 165 degrees (135 for rare lamb).

What it all comes down to is meat and heat. There are many things that happen when you cook a roast:

* Flavor changes as cell walls break down, mingling amino acids and proteins.

* Texture changes, from stringy and tough to firm and buttery, and finally to dry and tough.

* Juiciness (a function of both water in the meat and the saliva in the taster's mouth produced in reaction to the presence of fat) decreases as the water is squeezed from the meat fibers and the fat is rendered.

* Finally, and actually fairly unimportant to the cook, color changes (at least in beef and lamb) from red to brown. This is not, as one might suppose, because of the blood leaving the meat (in properly slaughtered meat, there is little blood left), but because of a molecular change in two related pigments called myoglobin and oxymyoglobin (pork, lacking these chemicals, is never red).

In our test kitchens, we experimented with three different means of roasting. First, we cooked a rack of lamb and a leg of lamb at high heat -- 450 degrees -- until they reached 135 degrees. Then we cooked the same cuts -- as nearly identical in weight as possible -- at a slow 325 degrees.

Looking at them side by side, the biggest difference was the color of the exterior. In the high-heat versions, the meat was nice and crusty brown. At low heat, the roasts were paler. The differences on the inside were not as great. The high-heat roasts tended to be a little stringier or more fibrous at the center; the ones cooked at lower heat were more uniformly buttery in texture.

To get the best of both, we figured we'd compromise. Since beef and lamb cook to a relatively low internal temperature, it's important to start them in a very hot oven -- 450 to 500 degrees -- to bring the surface to a high heat faster and start the browning process. (With smaller cuts of meat, you can brown the meat in a pan on top of the stove.) After 15 to 20 minutes, reduce the heat to around 325 to 350 degrees and let the roast cook slowly and evenly to the proper temperatures.

With pork, the situation is a little different. Since it cooks to a higher interior temperature, the initial browning is optional -- by the time the center of the roast hits 160, the exterior will already have begun to brown, but perhaps not enough for you if you're not using a spice coating on the meat. And by starting in a hot oven, you run the risk of overcooking a greater portion of the meat, resulting in dry, gray pork. We prefer to cook pork low and slow.

Remember, in all cases, the meat continues to cook after it is removed from the oven because of heat retained within the roast itself (the bigger the piece of meat, the more "push" you get). So subtract five degrees from smaller cuts and 10 or more from larger cuts in order to make the perfect compromise.

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