SCIENCE IN THE KITCHEN

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 contain- ing but a small amount of moisture, unless protected in some manner from the action of the heated air, or in some way sup- plied 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 de- gree of heat ; in short, she should thoroughly know her "machine" and its capabilities before at- tempting to use it for the cook- ing of food. An oven thermome- ter is of the utmost value for testing the heat, but unfortu- nately, 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 com- parison 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

An Oven Thermometer.

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the dei^rec of heat bearable will vary with every hand that tries it, each person Avho 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 \s 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 tempera- ture 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 impos- sible 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 mechan- ical 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 h

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

52 SCIENCE IN THE KITCHEN.

farina, milk, or at least part milk, is preferable, as it adds to tlicir nutritix'e \alue. In using- milk for cooking' 2)iirposes, it should be remembered that beini^ more dense than water, M'hen heated, less steam escapes, and consecjuently 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 ))e- low 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 simi- lar 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 chem- ical 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 ac- cordance with the object to be attained in their cooking. Foods from which it is desirable to extract the nutrient prop- erties, 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.

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When starch is added to several times its bulk of hot water, all the starch granules burst on approachins^^ the boiling point, and swell to such a degree as to occupy nearly the whole volume of the water, forming a pasty mass. Sugar is dissolved readily in either hot or cokl water. Cold water extracts albumen. Hot water coagulates it.

Steaviiiig, as its name implies, is the cooking of food by the use of steam. There are several ways of steaming, the most common of which is by placing the food in a perforated dish over a vessel of boiling Avater. For foods not needing the solvent powers of water, or which already contain a large amount of moisture, this method is preferable to boiling. Another form of cooking, which is usually termed steaming, is that of placing the food, with or without water, as needed, in a closed vessel which is placed inside another vessel containing boiling water. Such an apparatus is termed a double boiler. Food cooked in its own juices in a covered dish in a hot oven, is sometimes spoken of as being steamed or smothered.

Stewing is the prolonged cooking of food in a small quantity of liquid, the temperature of which is just below the boiling point. Stewing should not be confounded with simmering, which is slow, steady boiling. The proper temperature for stewing is most easily secured by the use of the double boiler. The water in the outer vessel boils, while that in the inner vessel does not, being kept a little below the temperature of the water from Avhich its heat is obtained, by the constant evaporation at a temperature a little below the boiling point.

Frying, which is the cooking of food in hot fat, is a method not to be recommended. Unlike all the other food elements, fat is rendered less digestible by cooking. Doubtless it is for this reason that nature has provided those foods which require the most prolonged cooking to fit them for use with only a small proportion of fat, and it would seem to indicate that any food to be subjected to a high degree of heat should not be mixed and compounded largely of fats. The ordinary way of frying, which the French call santeing, is by the use of only a little fat in a shallow pan, into which the food is put and cooked first

54 SCIENCE IN THE KITCHEN.

on one side and then the other. Scarcely anything could be more unwholesome than food prepared in this manner. A morsel of food encrusted with fat remains undigested in the stomach because fat is not acted upon by the gastric juice, and its combination with the other food elements of which the morsel is composed interferes with their digestion also. If such foods are habitually used, digestion soon becomes slow and the gastric juice so deficient in quantity that fermentation and putre- factive changes are occasioned, resulting in serious disturbance of health. In the process of frying, the action of the heat par- tially decomposes the fat ; in consequence, various poisonous substances are formed, highly detrimental to the digestion of the partaker of the food.

Adding Foods to Boiling Liquids. — ^Much of the sod- denne'ss of improperly cooked foods might be avoided, if the following facts were kept in mind : —

When vegetables, or other foods of ordinary tempera- ture, are put into boiling water, the temperature of the water is lowered in proportion to the quantity and the tempera- ture of the food thus introduced, and will not again boil until the mass of food shall have absorbed more heat from the fire. The result of this is that the food is apt to become more or less water-soaked before the process of cooking begins. This diffi- culty may be avoided by introducing but small quantities of the food at one time, so as not to greatly lower the temperature of the liquid, and then allowing the latter to boil between the introduction of each fresh supply, or by heating the food before adding it to the liquid.

Evaporation is another principle often overlooked in the cooking of food, and many a sauce or gravy is spoiled because the liquid, heated in a shallow pan, from which evaporation is rapid, loses so much in bulk that the amount of thickening requisite for the given quantity of fluid, and which, had less evaporation occurred, would have made it of the proper consis- tency, makes the sauce thick and unpalatable. Evaporation is much less, in slow boiling, than in more rapid cooking.

Measuring. — One of the most important principles to be observed in the preparation of food for cooking, is accuracy in

COOKERY. 55

measuring. Many an excellent recipe proves a failure simply from lack of care in this respect. Measures are generally more convenient than weights, and are more commonly used. The common kitchen cup, which holds a half pint, is the one usually taken as the standard ; if any other size is used, the ingredients for the entire recipe should be measured by the same. The following points should be observed in measuring: —

1. The teaspoons and tablespoons to be used in measuring, are the silver spoons in general use.

2. Any material like flour, sugar, salt, that has been packed, should either be sifted or stirred up lightly before measuring.

3. A cupful of dry material is measured level with the top of the cup, without being packed down.

4. A cupful of liquid is all the cup will contain without running over. Hold the cup in a saucer while measuring, to prevent spilling the liquid upon the floor or table.

Comparative Table of Weights and Measures. — The following comparative table of weights and measurements will aid in estimating different materials : —

One heaping tablespoonful of sugar weighs one ounce.

Two round tablespoonfuls of flour weigh one ounce.

Two cupfuls of granulated sugar weigh one pound.

Two cupfuls of meal weigh one pound.

Four cupfuls of sifted flour weigh one pound.

One pint of oatmeal, cracked wheat, or other coarse grains, weighs about one pound.

One pint of liquid weighs one pound.

One pint of meat chopped and packed solid weighs one pound.

Seven heaping tablespoonfuls of sugar = one cupful.

Five heaping tablespoonfuls of flour = one cupful.

Two cupfuls of liquid or dry material = one pint.

Four cupfuls of liquid or dry material= one quart.

Mixing Materials. ^ — In the compounding of recipes, vari- ous modes are employed for mingling together the different ingredients, chief of which are stirring, beating, and kneading.

By stirring is meant a continuous motion round and round with a spoon, without lifting it from the mixture, except to

56 SCIENCE IN THE KITCHEN.

scrape occasionally from the sides of the dish any portion of the material that may cling to it. It is not necessary that the stirring should be all in one direction, as many cooks suppose. The object of the stirring is to thoroughly blend the ingredi- ents, and this may be accomplished as well bj' stirring in one direction as in another.

Beating- is for the purpose of incorporating as much air in the mixture as possible. It should be done by dipping the spoon in and out, cutting clear through and lifting from the bottom with each stroke. The process must be continuous, and must never be interspersed with any stirring if it is desired to retain the air within the mixture.

Kneading is the mode by which materials already in the form of dough are more thoroughly blended together ; it also serves to incorporate air. The process is more fully described in the chapter on " Bread."

Temperature. — Many a cook fails and knows not why, be- cause she does not understand the influence of temperature upon materials and food. Flour and liquids for unfermented breads cannot be too cold, while for bread prepared with yeast, success is largely dependent upon a warm and equable tem- perature throughout the entire process.

Cooking Utensils. — The earliest cookery was probably ac- complished without the aid of any utensils, the food being roasted by burying it in hot ashes or cooked by the aid of heated stones ; but modern cookery necessitates the use of a greater or less variety of cooking utensils to facilitate the prep- aration of food, most of which are so familiar to the reader as to need no description. (A list of those needed for use will be found on page 66.) Most of these utensils are manufactured from some kind of metal, as iron, tin, copper, brass, etc. All metals are dissolvable in certain substances, and some of those em- ployed for making household utensils are capable of forming most poisonous compounds when used for cooking certain foods. This fact should lead to great care on the part of the housewife, both in purchasing and in using utensils for cooking purposes.

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Iron utensils, although they arc, when new, apt to dis- color and impart a disagreeable flavor to food cooked in them, are not objectionable from a health standpoint, if kept clean and free from rust. Iron rust is the result of the combination of the iron with oxygen, for which it has so great an affinity that it will decompose water to get oxygen to unite with ; hence it is that iron utensils rust so qu-ickly when not carefully dried after using, or if left where they can collect moisture. This is the reason why a coating of tallow, which serves to exclude the air and moisture, will preserve ironware not in daily use from rusting.

"Porcelain ware" is iron lined with a hard, smooth enamel, and makes safe and very desirable cooking utensils. German porcelain ware is unexcelled for culinary purposes.

"Granite ware" is a material quite recently come into use, the composition of which is a secret, although pronounced by eminent chemists to be free from all injurious qualities. Uten- sils made from it are light in weight, easily kept clean, and for most cooking purposes, are far superior to those made from any other material.

What is termed "galvanized iron" is unsuitable for cook- ing utensils, it being simply sheet iron coated with zinc, an exceedingly unsafe metal to be used for cooking purposes.

Tin, \\hich is simply thin sheet iron coated with tin by dip- ping several times into vats of the melted metal, is largely employed in the manufacture of cooking utensils. Tinware is acted upon by acids, and when used for holding or cooking any acid foods, like sour milk, sour fruits, tomatoes, etc., harm- ful substances are liable to be formed, varying in quantity and harmfulness with the nature of the acid contained in the food.

In these daj's of fraud and adulteration, nearly all the cheaper grades of tinware contain a greater or less amount of lead in their composition, which owing to its greater abun- dance and less price, is used as an adulterant of tin. Lead is also used in the solder with which the parts of tinware are united. The action of acids upon lead form very poison-

58 SCIENCE IN THE KITCHEN.

ous compounds, and all lead-adulterated utensils should be wholly discarded for cooking purposes.

Test for Lead- Adulterated Tin. — Place upon the metal a small drop of nitric acid, spreading it to the size of a dime, dry with gentle heat, apply a drop of water, then add a small crystal of iodide of potash. If lead is present, a yellowish color will be seen very soon after the addition of the iodide. Lead glazing, which is frequently employed on crockery and ironware in the manufacture of cooking utensils, may also be detected in the same manner.

Cooking utensils made of copper are not to be recommended from the point of healthfulness, although many cooks esteem them because copper is a better conductor of heat than iron or tin. The acids of man}^ fruits combine with copper to form extremely poisonous substances. Fatty substances, as well as salt and sugar, act upon copper to a greater or less degree, also vegetables containing sulphur in their composition, and pro- duce harmful compounds.

Utensils made of brass, which is a compound of copper and zinc, are not safe to use for cooking purposes.