This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
The best cooking temperatures for meat may not be the same for all conditions. As a general rule, it is agreed that low or medium temperatures are better than high ones for cooking meat. Yet some samples of meat do not seem to be toughened by any method of cooking; that is, if one deliberately sets out to show that higher temperatures toughen a piece of meat, while the same cut from the other side of the same animal cooked at a lower temperature is tender, the results are often not consistent.
Advantages of low temperatures. In general, lower cooking temperatures result (1) in less cooking loss, (2) in more juicy meat, (3) in more uniformly cooked meat, and (4) in longer cooking time. The meat is more uniform in color and more juicy throughout; whereas at a higher temperature, the meat is more gray and dry at the surface, there being a sharper contrast between the meat near the surface and that at the center of the cut. A longer cooking time may be an advantage, for the home-maker may safely leave the meat cooking while she attends church, etc.
Disadvantages of low temperatures. Often the meat (1) does not brown as attractively at the lower temperature, although occasionally the opposite is true, and (2) a longer cooking time is required. A long cooking time may also be a disadvantage.
Searing method. The Cooking Committee of Cooperative Meat Investigations formerly used a searing method for cooking experimental roasts of fresh meat. The roast was seared for 20 minutes at 250° to 275°C. (about 480° to 525°F.) and was then transferred to a second oven at 125°C. for the remainder of the cooking period. It was necessary to transfer experimental roasts to a second oven so that results from different laboratories could be compared, for different ovens cool at different rates. Obviously the homemaker cannot use two ovens. Hence a lower temperature, 200° to 240°C. (about 400° to 450°F.), is recommended for the house-wife in searing because the oven will remain at a fairly high temperature for some time after the temperature control has been set at the lower temperature.
Searing. Searing browns the meat, develops a characteristic surface flavor, and starts the cooking. Often the statement is made that searing by coagulating the muscle tissue on the surface prevents loss of interior fluids and extractives. Searing increases the cooking losses, though the losses may be largely surface ones. Searing also does not prevent the loss of interior juices in all instances.
Constant temperature method. At present the Cooking Committee uses a constant oven temperature 150°C. (about 300°F.) for cooking experimental roasts, with the exception of pork, which is cooked at 175°C. (about 350°F.). At this temperature the cooking time and losses are practically the same as for the searing method formerly used. The exterior is also browned to about the same extent, although it is sometimes less brown. The homemaker will find that in using a constant temperature excellent roasts will be obtained if she uses 150°, 125°, or 175°C. Some ovens will not hold as low a temperature as 125°C. (250°F.), even though the regulator carries this temperature. The meat will not brown as readily at the lower temperature, but this can be overcome by using a mixture of salt and sugar or sugar alone to sprinkle over the meat. The meat cooked at 175°C. will not be as uniformly cooked as at the lower temperature.
Stages to Which Meat Is Cooked: Rare, Medium, and Well Done
The longer a piece of meat is cooked, the more the interior color changes from pink or red to gray, and the greater the cooking losses. Some meats like veal and pork are cooked well done, whereas beef may be cooked rare. There is no definite stage between a rare and a medium-done piece of meat or between a medium well-done one and a well-done one. The meat passes from one stage to another gradually, so that there is no definite end point. Heat penetrates slowly into the interior of a large piece of meat, and the center of the meat, unless very much over-cooked, never attains as high a temperature as the meat near the surface.
Rare meat. Grindley and Sprague have suggested, for convenience, that meat with an interior temperature at its center of 60°C. or below be called rare. Such meats are juicier than meats cooked well done. Nearly all the interior may be a bright red color or only a small portion around the center of the meat may be red. The extent or uniformity of the red color depends upon the cooking temperature. As the heat penetrates the meat the color near the surface becomes gray. If the cooking temperature is high, this gray layer may extend nearly to the center of the meat. If the meat is cooked at a low temperature the gray color extends only a short depth and the color of the interior of the meat is nearly uniform. Thus it can be seen that if different cooking temperatures are used the interior of different pieces of meat cooked to the same inner temperature may vary decidedly in appearance. The intensity of the red color may vary with other factors as well as with the cooking temperature. The interior of cooked meat ripened 40 to 60 days is grayer in color than meat that has not been ripened. Veal cooked to the same inner temperature, and with the same cooking temperature, is grayer, and has less red color, than beef. Rare meat also has more of the original meat flavor than well-done meat, for not so much of the fluids and extractives giving flavor to the meat has been lost.
Medium well-done meat. Grindley and Sprague have suggested that meat that has reached an inner temperature of 60° to 70°C. be called medium well done. Here the color also varies with the temperature of cooking, the degree to which the meat has been ripened, and in some instances with the age of the animal and the kind of meat. Rare and medium well-done meats are probably more often associated with the color of the cooked meat. Since the color of the cooked meat varies with different conditions, the division into rare, medium well done and well done on the basis of inner temperature of the meat is only an arbitrary one and not always satisfactory. Most people would be agreed that medium well-done meat should not be a deep red or pink, but should show some pink color. Well-done meat. Meat that has a uniform gray color throughout the entire interior of the meat is usually called well done. With veal, this stage of cookery is sometimes reached before or by the time the inner temperature of the meat has reached 71°C. This may also be true of beef that has ripened sufficiently. Unripened beef requires a higher temperature than 7l°C. before a uniform gray color is attained, when a low cooking temperature is used. But to some persons the term well done is associated with the degree of cookery, that is, the separation of the muscle fibers due to formation of gelatin from the connective tissue. It may also refer to the dryness of the meat and the loss of juices. The meat may be cooked until it reaches a temperature far above 7l°C, often from 80° to 85°C. for roasts and from 95° to 99°C. for braised meat.