This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
Vernon determined the shrinkage in dressing and cooking poultry, using fryers, roasters, and hens. Lowe and Vernon determined the dressing and cooking losses for broilers, fryers, roasters, capons, and hens. All the poultry was roasted except the fryers and broilers. The broilers were broiled under a gas flame in the oven, the fryers were dredged in flour and fried in fat. In frying, the lean fryers absorbed fat, and the fat ones lost fat.
The inedible portion includes the weight of all parts of the fowls served but not eaten.
Methods and cooking temperatures. In roasting poultry, one is confronted with the problem of cooking tender and less tender muscles at the same time. As a result, when the breast is at its prime, the thigh and leg muscles may be slightly tough and, vice versa, when the thigh and leg are cooked sufficiently to soften the connective tissue, the breast is past its prime and is becoming dry.
Another problem in cooking poultry is the skin. If it is moist and tender, the appearance is less attractive because it is not so brown. When the skin is not consumed this point is not important.
The degree of fatness and its distribution, the degree of post-mortem changes or ripening, the age, and the size may affect the cooking time and losses of roasters. In addition, breed, sex, and the feed the bird has received may have some effect on these factors. Hence, for fair experimental tests the cuts should be paired. To do this Lowe and Keltner divided roasting chickens into halves, the halves being tested one against the other to determine the effect of the cooking temperature, covering the pan, and basting on cooking losses, cooking time, and palatability of the meat. They found the cooking losses were practically the same for halves cooked at 125°C. (about 250°F.) and at 175°C. (about 350°F.), but the cooking time at the lower temperature was more than twice as long as at the higher temperature. The differences in palatability scores for the breast and thigh meat cooked at the two temperatures were practically negligible, with the exception that the breast scored higher in juiciness at the higher temperature, which was probably related to the shorter cooking time. One drawback in cooking halves of birds was the tendency for the muscles of the breast to separate and draw back, which is of course not encountered in roasting the whole bird. In all these tests the half of chicken was removed from the oven when the interior temperature of the thigh was 85°C. (185°F.).
If a searing instead of a constant temperature method is desired, cooking the roast uncovered for 20 minutes at 200°-230°C. (about 395°-450°F.) and then lowering the temperature to 125°C. for the remainder of the cooking period produces a juicy roast. Covering for the last 20 or 30 minutes of cooking increases the tenderness of the skin, as the confined steam moistens the skin.
In tests of the searing and constant temperature methods for cooking turkeys, in an uncovered pan and basting the turkey every half hour, the constant temperature of 150°C. (about 300°F.) has in general proved very satisfactory, the meat being tender and very juicy.
Covered and uncovered pans. Lowe and Keltner cooked halves of 22 birds covered, the other halves uncovered. All were cooked at a constant oven temperature of 150°C. and until the interior temperature of the thigh reached 85°C. The cooking time was approximately twice as long for uncovered as for covered halves. The total and volatile cooking losses were greater for the uncovered halves, but the drippings were greater for covered halves. The scores showed that in aroma, flavor, and juiciness the breast of the uncovered halves was more desirable than the breast of the covered halves. No preference for the thigh was shown for either covered or uncovered halves.
Covering the birds for the last 20 minutes of the cooking period shortened the cooking time, decreased the cooking losses, and increased the tenderness and palatability of the skin but not of the meat. The majority of the scorers preferred the uncovered halves.
Interior temperatures for cooking poultry. The insertion of thermometers into muscles of chicken in early tests was not satisfactory, as the thermometer and bulbs were too large. However, it was found that the larger thermometers could be used successfully by inserting them into the stuffing, either through the front or rear cavities of the fowl. For turkeys and geese the thicker part of the stuffing is towards the rear of the carcass; hence it was preferable to insert the thermometer at the rear.
Lowe and Keltner used in their study a small light thermometer with a very short, small bulb. Placing the bulb of the thermometer into the thickest portion of the thigh muscles and cooking the chicken until a temperature of 85 °C. was reached proved satisfactory. The most desirable temperature to which the breast muscles should be cooked has not been determined. Since the breast muscles tended to separate when half of a bird was cooked, thermometers were not used successfully in the breast. However, in the preliminary studies the temperature of the breast was usually 2° to 4° higher than that of the thigh.
Evidently the meat of large fowls is juicier if the interior temperature of the stuffing is lower than for small fowls. This is probably due to their size, the large quantity of stuffing that they hold increasing the distance to the middle of the stuffing.
When chickens were roasted until the interior temperature of the stuffing reached 80° to 83°C, the meat was desirable; but, when cooked to 85°C, the breast of some birds was dry, the drippings and particularly their moisture content increasing rapidly in the last few minutes of cooking. This might indicate that for some birds, depending somewhat upon degree of ripening and other factors, this is a critical temperature. As this point is reached or exceeded, the tendency for the meat of the chicken is to become dry and the drippings loss to increase.
For turkeys weighing 16 to 20 pounds after stuffing, an interior temperature of 75° to 82°C. of the stuffing resulted in juicy meat. But for turkeys weighing 25 to 30 pounds after stuffing a lower temperature gives better results. The type of stuffing used may make some difference in the juiciness of the meat and the cooking losses. Lowe and Keltner found that stuffing made from 1-day-old bread, 100 grams, butter 50 grams, and salt 2 grams, but without the addition of liquid, absorbed an average moisture content of 41.5 per cent. The amount of moisture absorbed varied from 14.6 to 78.1 per cent.