Roasting Part I
Roasting Basics

"Roasting" is a vague term because it is one of the most ancient methods of cooking. Why is Roasting one of the most ancient cooking methods, you may ask? Is it because there were ovens in the ancient world? No, although there were indeed ovens, most were open and cooked by conduction. The meat or bread sat on the hot oven floor, by which heat was directly conducted into the food. No, it is because cooking meat over an open fire on a rod is called "spit-roasting." The meat is cooked by radiant heat given off by the fire as it is turned by hand to cook on all sides. Today we would probably consider spit-roasting a form of grilling. And that makes sense, because grilling is cooking by radiant heat coming from below the food.

Today, roasting generally refers to cooking foods by convection heat, specifically hot dry air, coming at the food items from all directions. The environment for roasting is usually an oven, a closed oven. What then is baking? Baking is the same thing. Sometimes meats and poultry are said to be "roasted," as in roast duck, while breads, pastries, vegetables, and fish are said to be "baked," as in baked salmon. Also, sometimes large food items are said to be "roasted," as in roast beef, while smaller portion-sized foods are said to be "baked," as in baked potatoes. However, hams are baked, not roasted, and garlic is roasted, not baked. So there is no uniform rhyme or reason for the terminology.

The three ways of cooking food are as follows: conduction, radiation, and convection.

(1) Conduction is the direct transfer of heat by contact with the food, as when an egg cooks because it is in direct contact with a hot frypan or meat browns when in contact with a hot sauté pan.

(2) Radiation is the heating of food by radiation, that is to say, wave energy. Radiation or wave energy is not heat, but becomes heat when it contacts food. At contact, it increases the motion of the molecules in the food, which is heat. In technical terms, the wave energy becomes kinetic energy in the food. Broiling and grilling use infrared waves given off by fire or hot electric elements; microwave ovens use electro-magnetic waves; and GE's new Advantium oven uses light waves. See our discussion Grilling - Part I for more detail on radiation.

(3) Convection is the transfer of heat through a medium to the food. The medium may be air, steam, or liquid, such as water or oil. Roasting a chicken in an oven, steaming vegetables in a wok, poaching a salmon in water, and deep frying potatoes in peanut oil are all examples of cooking by convection.

Roasting and baking, then, is cooking foods by convection surrounding the food items with hot dry air in an enclosed oven. Braising is cooking foods by both conduction and convection in a liquid (see our discussion on Braising). Poaching is cooking by convection in a liquid (see our discussion on Poaching).

There are three methods of roasting distinguished by the level of heat used. They are as follows:

(1) Slow Roasting - heat is 200º Fahrenheit
(2) Medium Roasting - heat is 250º - 350º Fahrenheit
(3) Fast Roasting - heat is 375º - 500º Fahrenheit

The appropriate method depends primarily upon the size of the item. Small or thin items can be fast roasted, but large, thick bulky items should be slow roasted. Why the difference?

All foods contain a large amount of water. Meat is 75% to 80% water. Heat drives water from food. Also, meat proteins shrink and lose moisture as they are heated. The denaturing or unraveling of meat proteins begins between 104º and 122º. They lose their ability to be dissolved in water and consequently clump together, expelling the water in which they normally operate. At 140º to 150º they dramatically shorten and toughen. Most meat is well done at 155º to 160º.  (For more detail, see our discussion Grilling - Part II).

As food cooks in an oven, the heat is conducted from the outer part of the food item into the center. The center needs to get to 130º to be rare. A large food item in a moderately hot oven, about 325º, will over cook before the center gets to the point of just being rare. A huge amount of moisture, which contributes to tenderness and juiceness, and also fat, which contributes to flavor, will be lost as the outer part toughens and solidifies. You can imagine what happens to the outer part if the item is cooked until well done (155º) in the center.

It is important to keep in mind that the oven is always a lot hotter than the food needs to be, to be well done, let alone rare. Even when slow roasting, the oven will be 200º, where as it is well done at 160º and rare at 130º.

    Crucial Temperatures: Slow Roast Oven 200º F, Well Done 160º, Rare 130º

The trick is to get the center of the food item to the temperature you desire, while not over cooking the outside portion of it.

A few more temperatures that are crucial. First, the trichinosis parasite in pork is killed at 137º. To be safe, pork should be cooked to 150º.

    Pork: trichinosis parasite killed at 137º; pork should be cooked to 150º.

Finally, poultry white meat is fully done at 152º; poultry dark meat at 165º - 175º. That makes roasting a chicken a problem. How do you get the dark meat done without overcooking the white meat?

    Poultry: white meat fully done at 152º; dark meat at 165º - 175º.