A text-book of cooking

How does the temperature of fat hot enough for frying compare with that of boiling water ? Why is an iron kettle preferable to one of tin or granite for heating fat? (See note under Peanut Candy recipe, p. 30.) J FAT AS A FRYING AND SAUTEING MEDIUM 85 What happens to foods that are cooked in fat too cool for frying ? (See Experiment 29, p. 78.) What is the purpose of covering with egg, mixtures that are to be fried ? How should the egg be prepared for " dipping" ? How can the remaining white or half an egg be utilized in prepar- ing Potato Croquettes ? If "left over" mashed potatoes are used for making croquettes, what ingredient in the recipe above should be omitted ? DIVISION POUR ENERGY-GIVING AND BODY-BUILDING FOODS: PROTEIN LESSON XXIII Eggs l Protein, a Body-Builder. — A steam engine requires not only fuels for its greatest usefulness but occasional repair. The body also needs both fuel and repairing materials. However, a steam engine needs only occasional repair, while the body needs constant repair. The function of the foods considered thus far is to give energy to the body. But there is another great class of foods, or foodstuffs — those included under the term protein — that not only give energy to the body but also build up and repair it. The process of repairing takes place in the body cells. Hence the body differs from an engine in that it possesses the property of self-repair. Since the slightest using of the body causes the wearing away of some of the tissues, the body-building power of protein is especially important. Albumin in Eggs. — One of the protein substances oc- curring in foods in large quantities is albumin. Eggs con- tain considerable albumin. The white of egg consists of albumin and water enclosed in millions of cells. When the egg white is separated from the yolk and the 1 Note to the Teacher. — If the egg lessons come in the mid-winter months, they may be omitted until eggs are reasonable in price ; or the " theory " concerning eggs and the experiment concerning the tempera- ture of cooking protein foods may be given, and the cooking of eggs may take place later in the year. 86 i shell, explain why it remains massed together, i.e. does not separate into particles. Experiment S3: The Solubility of Albumin. —Put, the white of an egg in a dish and break the membranes by cutting with a pair of scissors. Then place a small quantity of the while of egg in a test tube, add a little cold water, and shake the tube. Is albumin soluble in cold water ? How do you account for the foaming on the surface ? Experiment 84: The Coagulation of Albumin. — Apply heat to the diluted white of egg of Experiment 33. Into what form is the liquid albumin changed by heat ? When eggs are cooked, the albumin in the white stiffens or coagulates. The yolk also contains a kind of protein which coagulates when heated. Experiment SB i Temperature at which Eggs Coagulate. — Place a tea- spoonful of white of egg in a test tube. Insert a thermometer in the test tube and place the test tube in a beaker of water (see Fig. 28). Heat the water gradually. Note and record : (a) Temperature at which coagula- tion first appears. (6) Temperature at which the egg- white is entirely coagulated. Has the water reached the boiling point when the egg-white has entirely coagulated 1 What application can you draw from this as to the temperature of the water in which eggs may be cooked ? Experiment 36: Comparison of ^ Cooked and Boiled Eggs. — Remove at one .bout blrtl of the collated .gg „ 26.-Appmi.tm U de«r- from lb. ten tub. 1 Eiper.m.nt 86. m , no _ „ whfch Examine it and press it between the , , Brigm. . BE .c» K u.,i.. Continue to heat the remainder of the egg in the test tube, allowing the water to boil a few minutes. Then remove the ■ 88 THE COOKING OF FOODS