Experiment 39

To determine the effect on beef roasts of cooking to different stages of doneness.

1. Preparation. Weigh the roast. Wipe with a damp cloth. A tracing may be made of the cut surfaces of the meat. Determine the place and depth for insertion of the thermometer. Measure the width of the roast. The thermometer is inserted half way. See Fig. 23, p. 225. To determine the depth to insert the thermometer, measure the distance on the two cut surfaces as indicated in Fig. 25, diagram D, p. 234. The distance should be the diameter of a circle, so that the bulb of the thermometer can be inserted equally distant from the top, the chine bone, and the bottom of the roast. If the depth on one cut surface is 4 inches and on the other 4 1/2 inches, use an average of these two, or 4 1/4 inches, for the distance represented by the diameter of the circle. Measure up from the center of the thermometer bulb 2 1/8 inches on the stem and insert to this depth in the roast. The incision for the thermometer should be made with a very narrow knife blade, about 1/4 inch in width, or a skewer so that the meat will fit tightly around the thermometer. For a rolled roast find the radius (one-half of the diameter) and insert the center of thermometer bulb to this depth in the middle between the two ends of the roast.

Weigh the thermometer and the cooking pan. Use an open pan. A common, sheet-iron pan is suitable for roasting. A standing-rib roast rests on the chine bone and rib ends, which keeps the roast above the drippings. See Fig. 23. A rolled roast is laid on a rack with the fat side up. No water or seasoning are added. Record the inner temperature of the roast and oven at definite intervals, 10, 15, or 20 minutes, during the cooking period. Cook by one of the following methods. If paired roasts are used, one may be cooked by a searing, the other by a constant temperature method.

Searing method. For experimental comparisons sear the roast for 20 minutes at 250°-275°C. (about 480°-525°F.) and transfer at the end of 20 minutes to an oven at 125°C. (about 255°F.). For a searing method suitable for the home, sear at 220°C. (about 425°F.) for 20 minutes, then set the regulator for 125°C. (about 255°F.).

Constant temperature method. Place the roast in an oven with temperature of 150°C. (about 300°F.).

Cook the roast until the thermometer registers 55°C. (131°F.). Note exterior appearance on removal from the oven. Note and record any change in interior temperature of the roast. When the temperature is constant, weigh the roast. Weigh pan and drippings. Cut the roast through the center. Describe its condition, its color, and uniformity of color throughout the roast, its sheen and amount of juice on the surface. Score for tenderness, flavor, and juiciness.

If the volatile and drippings losses in the oven are to be determined separately from those after removal from the oven, the roast is weighed at the time it is removed from the oven and transferred to a weighed platter. When the maximum temperature is reached, the roast is reweighed to determine the volatile loss during the interval after removal from the oven and attainment of maximum interior temperature. The platter is reweighed to determine the drippings collected outside the oven.

Samples for scoring. For scoring cut off the outside slice and lay aside, as the browned part will affect the flavor. Cut as many slices as there are people to score. Cut from the same position in each roast and be sure that the same person gets slice 1 from all roasts, etc. If slices are very large they may be divided, but the same portion of each muscle should be given to the same scorer.

Determine the percentage lost during cooking, the dripping loss and the volatile loss. Plot on graph paper the rise in inner temperature of the roast, during cooking and after removal from the oven. The weight of the bones and the per cent edible may also be determined. Calculate the time per pound required for cooking.

2. Repeat 1, but do not remove the roast from the oven until the inner temperature is 63°C. (145°F.). If desired the roast can be removed when the interior temperature reaches 61°C. Compare with 1 for color, juiciness, tenderness, flavor, loss of weight, and rise of temperature after removal from the oven.

3. Repeat 1, but do not remove from the oven until the inner temperature is 75°C. Compare with 1 and 2.

The following headings are suggested for records and may be used in all the following experiments, unless otherwise suggested. Where several roasts are to be cooked it is better to have mimeographed sheets for making records.

Weight before cooking

Weight after cooking, grams

Total loss, grams

Fat loss, grams

Volatile loss, grams

Total loss, per cent

Fat loss, per cent



Volatile loss, per cent

Interior temperature when removed from oven,


Maximum temperature reached,


Time after removal from oven to obtain maximum temperature

Total time of cooking, minutes

Time of cooking per pound, minutes

Weight of edible cooked portion, grams

Edible portion, per cent






Results and conclusions.

Experiment 40

To determine the rate of temperature rise near the surface of the roast as compared with the center of the roast.

1. Repeat Experiment 39,1, but place a second thermometer 1/2 inch from the surface of the roast. Take the readings on both thermometers every 10 minutes. Remove from the oven when the temperature at the center is 55°C. Continue to record the changes in temperature. What differences do you note in the changes of temperature in the two portions of the roast? Plot on graph paper the rise in temperature in the two portions of the roast. Compute losses and make records as suggested under Experiment 39.

Experiment 41

To determine the effect of cooking at different temperatures on standing beef rib roasts.

Three pairs of two-rib roasts can be obtained from one carcass, the pairs consisting of ribs 11 and 12, 9 and 10, and 7 and 8. These pairs can be used to compare the cooking losses, the exterior and interior color, the juiciness, tenderness, and flavor of roasts cooked at various temperatures. See the following suggestions. Cook the roasts to the same interior temperature, 63°C. (If desired either 55°C. or 75°C. may be used.)

1. a. Use a constant oven temperature of 125°C. for cooking one roast of the pair.

b. Cook the other roast at a constant temperature of 225°C.

2. Compare the effect of constant oven temperatures of 125°C. and 175°C.

3. Repeat (2) but compare 125°C. and 150°C.

4. Repeat (2) but compare 150°C. and 175°C.

5. Repeat (2) but compare 150°C. and 225°C.

6. Use the experimental searing method (20 minutes at 250°-275°C., then transfer the roast to a second oven at 125°C.) with a constant temperature of 125°C.

7. Repeat (6) but compare the searing method and a constant temperature of 150°C.

The lower searing temperature may be substituted for the experimental searing method in any of the above suggestions. In addition the experimental searing method may be used with temperatures of 150°C. and 175°C. to complete the cooking.

If rolled instead of standing rib roasts are used, they should be placed on racks to keep them above the drippings. Compute losses and make records as suggested under Experiment 39.

What is the interior temperature of a roast which is rare? Of a medium well-done roast? Of a well-done roast? In each case what was the number of minutes per pound required for roasting? What is the effect of increasing the size of the roast on the time required per pound? How much did the inner temperature of roasts rise after removal from the oven? What factors cause variations in this rise in temperature? If a rare roast is to be served immediately, at what temperature would you remove it from the oven? Is the rate of increase of inner temperature of the different roasts constant?