This section is from the book "Elements Of The Theory And Practice Of Cookery", by Mary E. Williams. Also available from Amazon: Elements Of The Theory And Practice Of Cookery; A Textbook Of Domestic Science For Use In Schools.
A. Examine a piece of round of beef, noting its fibrous appearance. Can you see any fat among the fibres? Scrape with, a knife first one side, then the other, of one of the pieces of meat from which the juice has been squeezed, until only the fibres are left. Pick some of them apart with a needle. Try to break or tear them.
B. Heat the mass of fibre, and note the effect.
Each fibre is a bundle of tube-shaped cells covered and bound together with a web of white connective tissue, threaded by tiny blood-vessels. Toward the ends of the muscles the fibres dwindle down till only a firm mass of connective tissue, called tendon, is left. The contents of the tubes and blood-vessels may be scraped out, leaving these, with the connective tissue, in a pale-colored, stringy mass.
Directions for making raw beef sandwiches (for invalids).
What two animal foods have we already used and studied ? What important foodstuff have we found in both of these? (Pp. 88 and 95.) How can we find out if it is also in meat?
A. Dry some meat slowly for several hours. Heat a little of it in a test-tube with lime. What odor do you notice? What foodstuff is present?
B. Nitric acid test for protein. Caution. - This test must be made only by the teacher or some person experienced in handling chemicals. Nitric acid is a dangerous fluid. Put a few bits of meat into a test-tube with a little water. Add a few drops of nitric acid. Boil two or three minutes. A bright yellow color appears. Let cool and add a few drops of ammonia. The color turns to deep orange.
Any food material may be tested in this way for protein. To test raw white-of-egg, cut it with scissors until half a teaspoonful can be taken up. Put this in a test-tube, and add the nitric acid.
Use a one-half pound slice of the top round of beef cut three-fourths of an inch thick. Place it in a wire broiler. Sear both sides quickly, turning it frequently until it swells and becomes spongy. Cut it into small pieces. Squeeze these, a few at a time, in a meat press, vegetable press, or lemon squeezer. Half a pound of meat should yield two ounces of juice.
Heat beef-juice in a test-tube. Note that flakes form in it, and that the red color disappears.
Lean meat contains albumin dissolved in much water. It also contains other proteins some of which are not soluble in water. There are also present small amounts of other nitrogenous substances, not proteins, called extractives. Practically all the proteins are coagulated by heat. Also in solution are various mineral salts. The red color of meat, which is destroyed by heat, is due to iron salts in the blood.
Connective tissue consists largely of collagen. Heat causes collagen to swell and force the juice out of the muscle fibres. In preparing beef-juice, the object is to heat the meat just enough to express the juice, but not enough to coagulate the protein in it. A mass of connective tissue, as a whole, shrinks when heated, owing to loss of water. Dry heat both shrinks and hardens it.
Cut into small bits one pound of beef from the top round. Put it in a glass jar, sprinkle with salt, put on the cover, and set the jar, wrapped in cloth, or supported on a trivet, in a kettle of cold water. Heat the water till it steams, and keep it as near this same temperature as possible until the meat is colorless and the juice looks rich and thick. Do not strain.
If the beef-tea could be kept at just the right temperature, the proteins would remain dissolved. This can hardly be U. S. Department of Agriculture Office of Experiment Stations A. C. True: Director accomplished, however. If, therefore, the tea should be strained, it would no longer be nutritious, though the extractives remaining in it would give it a strong meat flavor.
Prepared by C. F. Langworthy Expert in Charge of Nutrition Investigations
Composition Of Food Materials
A. Cover a bit of raw meat with cold water, and observe how quickly the water becomes red. What does this show? Is anything besides blood drawn out? B. Filter the water through filter-paper and heat the filtrate; i.e., the liquid that passes through. Has any albumin dissolved in the water? C. Sprinkle a bit of raw meat with salt. What does the salt do to the juices of the meat? How do these afterward act upon the salt?
What conclusions do you draw from these experiments with regard to (1) putting meat into water to wash it, and (2) salting meat before cooking it?
As soon as meat is brought into the house, take it out of the wrapping-paper, wipe it with a damp cloth, cut out any part discolored by a meat-hook, and set it away in a cool place.
Meat is cooked, not to make it more digestible, but chiefly to improve its flavor, and to soften the connective tissue.