Science in the Kitchen. E. E. Kellogg
keep them closed, or partially so, and not waste fuel. There is no economy in allowing a fire to get low before fuel is added; for the fresh fuel cools the fire to a temperature so low that it is not useful, and thus occasions a direct waste of all fuel necessary to again raise the heat to the proper degree, to say nothing of the waste of time and patience. The addition of small quantities of fuel at short intervals so long as continuous heat is needed, is far better than to let the fuel burn nearly out, and then add a larger quantity. The improper management of the drafts and dampers has also much to do with waste of fuel. As stoves are generally constructed, it is necessary for the heat to pass over the top, down the back, and under the bottom of the oven before escaping into the flue, in order to properly heat the oven for baking. In order to force the heat to make this circuit, the direct draft of the stove needs to be closed. With this precaution observed, a quick fire from a small amount of fuel, used before its force is spent, will produce better results than a fire-box full under other circumstances.
An item of economy for those who are large users of coal, is the careful sifting of the cinders from the ashes. They can be used to good advantage to put first upon the kindlings, when building the fire, as they ignite more readily than fresh coal, and give a greater, quicker heat, although much less enduring.
Methods of Cooking.—A proper source of heat having been secured, the next step is to apply it to the food in some manner. The principal methods commonly employed are roasting, broiling, baking, boiling, stewing, simmering, steaming, and frying.
Roasting is cooking food in its own juices before an open fire. A clear fire with intense heat is necessary.
Broiling, or grilling, is cooking by radiant heat over glowing coals. This method is only adapted to thin pieces of food with a considerable amount of surface. Larger and more compact foods should be roasted or baked. Roasting and broiling are allied in principle. In both, the work is chiefly done by the radiation of heat directly upon the surface of the food, although some heat is communicated by the hot air surrounding the food. The intense heat applied to the food soon sears its outer surfaces, and thus prevents the escape of its juices. If care be taken frequently to turn the food so that its entire surface will be thus acted upon, the interior of the mass is cooked by its own juices.
Baking is the cooking of food by dry heat in a closed oven. Only foods containing a considerable degree of moisture are adapted for cooking by this method. The hot, dry air which fills the oven is always thirsting for moisture, and will take from every moist substance to which it has access a quantity of water proportionate to its degree of heat. Foods containing but a small amount of moisture, unless protected in some manner from the action of the heated air, or in some way supplied with moisture during the cooking process, come from the oven dry, hard, and unpalatable.
Proper cooking by this method depends greatly upon the facility with which the heat of the oven can be regulated. When oil or gas is the fuel used, it is an easy matter to secure and maintain almost any degree of heat desirable, but with a wood or coal stove, especial care and painstaking are necessary.
It is of the first importance that the mechanism of the oven to be used, be thoroughly understood by the cook, and she should test its heating capacity under various conditions, with a light, quick fire and with a more steady one; she should carefully note the kind and amount of fuel requisite to produce a certain degree of heat; in short, she should thoroughly know her "machine" and its capabilities before attempting to use it for the cooking of food. An oven thermometer is of the utmost value for testing the heat, but unfortunately, such thermometers are not common. They are obtainable in England, although quite expensive. It is also possible at the present time to obtain ranges with a very reliable thermometer attachment to the oven door.
A cook of good judgment by careful observation and comparison of results, can soon learn to form quite a correct idea of the heat of her oven by the length of time she can hold her hand inside it without discomfort, but since much depends upon the construction of stoves and the kind of fuel used, and since the degree of heat bearable will vary with every hand that tries it, each person who depends upon this test must make her own standard. When the heat of the oven is found to be too great, it may be lessened by placing in it a dish of cold water.
Boiling is the cooking of food in a boiling liquid. Water is the usual medium employed for this purpose. When water is heated, as its temperature is increased, minute bubbles of air which have been dissolved by it are given off. As the temperature rises, bubbles of steam will begin to form at the bottom of the vessel. At first these will be condensed as they rise into the cooler water above, causing a simmering sound; but as the heat increases, the bubbles will rise higher and higher before collapsing, and in a short time will pass entirely through the water, escaping from its surface, causing more or less agitation, according to the rapidity with which they are formed. Water boils when the bubbles thus rise to the surface, and steam is thrown off. If the temperature is now tested, it will be found to be about 212° F. When water begins to boil, it is impossible to increase its temperature, as the steam carries off the heat as rapidly as it is communicated to the water. The only way in which the temperature can be raised, is by the confinement of the steam; but owing to its enormous expansive force, this is not practicable with ordinary cooking utensils. The mechanical action of the water is increased by rapid bubbling, but not the heat; and to boil anything violently does not expedite the cooking process, save that by the mechanical action of the water the food is broken into smaller pieces, which are for this reason more readily softened. But violent boiling occasions an enormous waste of fuel, and by driving away in the steam the volatile and savory elements of the food, renders it much less palatable, if not altogether tasteless. The solvent properties of water are so increased by heat that it permeates the food, rendering its hard and tough constituents soft and easy of digestion.
The liquids mostly employed in the cooking of foods are water and milk. Water is best suited for the cooking of most foods, but for such farinaceous foods as rice, macaroni, and farina, milk, or at least part milk, is preferable, as it adds to their nutritive value. In using milk for cooking purposes, it should be remembered that being more dense than water, when heated, less steam escapes, and consequently it boils sooner than does water. Then, too, milk being more dense, when it is used alone for cooking, a little larger quantity of fluid will be required than when water is used.
The boiling point for water at the sea level is 212°. At all points above the sea level, water boils at a temperature below 212°, the exact temperature depending upon the altitude. At the top of Mt. Blanc, an altitude of 15,000 feet, water boils at 185°. The boiling point is lowered one degree for every 600 feet increase in altitude. The boiling point may be increased by adding soluble substances to the water. A saturated solution of common baking soda boils at 220°. A saturated solution of chloride of sodium boils at 227°. A similar solution of sal-ammoniac boils at 238°. Of course such solutions cannot be used advantageously, except as a means of cooking articles placed in hermetically sealed vessels and immersed in the liquid.
Different effects upon food are produced by the use of hard and soft water. Peas and beans boiled in hard water containing lime or gypsum, will not become tender, because these chemical substances harden vegetable casein, of which element peas and beans are largely composed. For extracting the juices of meat and the soluble parts of other foods, soft water is best, as it more readily penetrates the tissue; but when it is desired to preserve the articles whole, and retain their juices and flavors, hard water is preferable.
Foods should be put to cook in cold or boiling water, in accordance with the object to be attained in their cooking. Foods from which it is desirable to extract the nutrient properties, as for broths, extracts, etc., should be put to cook in cold water. Foods to be kept intact as nearly as may be, should be put to cook in boiling water.
Hot and cold water act differently upon the different food elements. Starch is but slightly acted upon by cold water. When starch is added to several times its bulk of hot water, all the starch granules burst on approaching the boiling point, and swell to such a degree as to occupy nearly