1. Why is the question of the cost and kind of fuel important?
2. What is the difference between hard and soft coal? Between red and white ash?
3. Why are certain fuels in more common use than others?
4. Explain the advantage of gas over coal. Over kerosene.
5. What are the advantages of electricity as a source of heat?
6. Explain the way in which electricity is measured.
7. Read the gas meter at home and estimate the amount and cost per day.
(The ordinary burner consumes about two cubic feet per hour.)
8. Obtain the prices of the fuels used in the neighborhood and work out a comparison of the cost of fuel for preparing a meal.[8]
9. What are the methods of conserving heat in cooking apparatus?
10. Explain the structure and management of a coal stove.
11. Explain the principles involved in making a fire.
12. The structure and management of a gas stove.
13. Why does gas in a burner sometimes "pull back"?
14. State the requirements in a perfect example of cooking apparatus.
CHAPTER IV
FOOD PREPARATION, THE PRINCIPLES AND TECHNIQUE
=The principles of cooking.=--In science the word "principle" ordinarily means a formulation of some _general_ or _constant mode of behavior_--a generalization based on many observations of fact. In cookery the word is used in the same sense; for example, one may say that an important principle to bear in mind when cooking with any fat is that the fats may be melted without decomposition, but when too strongly heated they begin to decompose with the production of acrid and irritating products.
Sometimes, however, we speak of "principles of cookery" in a broader and somewhat less exact sense to indicate the _general purposes_ of cooking operations, as when we say that the most important principle of vegetable cookery is to soften the fiber without destroying the flavor or dissolving away the ash const.i.tuents of the vegetable.
That is, the change either chemical or physical that takes place in a certain foodstuff by the application of heat or cold or by the use of a fermentation process may be referred to as the underlying, working principle. We shall study in detail these changes as we experiment with and prepare each food material, but a general statement of the effect of heat on various foodstuffs will be helpful here.
_Protein._--There are several forms of protein, with differences that we can understand only after a thorough study of chemistry. The most important proteins in meat, fish, eggs, milk, old beans and peas coagulate, or become slightly harder or firmer at a temperature below the boiling point of water. We shall perform an experiment to show this while studying the egg. There is no marked chemical change; that is, the protein is not changed to another substance.
_Fats._--Solid fats are liquefied by heat, and freed from the tissue that contains them in animal fats like suet.
When a fat begins to smoke with heat, a chemical change is taking place.
If intense heat is continued, all the hydrogen and oxygen are driven off and pure carbon remains. When the fat is "brown," giving the flavor we like, a part of the oxygen and hydrogen have been driven off. The "boiling" of fat in a kettle is ordinarily due to the boiling of the water contained in the fat.
_Starch._--Starch occurs in the form of granules. See Fig. 39. In boiling water, the granule expands and finally bursts, and frees the content, the pure starch, and the whole ma.s.s thickens.
Boiled with an acid the starch is changed to dextrin, a substance resembling a gum, and the mixture becomes thin; and this process continued changes the dextrin to dextrose.
With intense "dry" heat, as in toasting, the granule expands and opens, and the contents change to dextrin. Continued heat reduces the starch to pure carbon. The brown color and pleasant flavor in toast are a stage on the road to carbon.
_Sugar._--Sugar first melts with heat, then begins to decompose, giving off water. This is also a stage on the road to pure carbon. Caramel, a familiar flavor, is sugar in the brown stage, with the water partly driven off.
The art in applying intense heat to fat, starch, and sugar is to know the stopping point,--to reach the "brown taste" and stop short of the "burnt taste."
_Mineral matter._--The "ash" remains for the most part unchanged by heat, but may be lost in the water in which vegetables and meat are cooked if the water is thrown away.
_Vegetable fiber_ is softened by heat and moisture, and the protein, starch, fat, and sugar are freed, making them available for our digestion and nutrition.
_Meat fiber_ softens at a low temperature, that is, below the boiling point of water, with moisture; continued intense heat shrinks and hardens it. A tender steak fried with fat in a hot pan will soon resemble sole leather.
=The technique of food preparation.=--From the moment the food materials enter the kitchen until the unusable portions are destroyed or carried away, there is a best way of working with them at each step, and the sum of these may be said to make a good technique. This technique will include cleanliness first and foremost, then skill in the use of tools, judgment in managing cooking apparatus and in applying heat in cooking processes, and accuracy and rapidity of execution. It will also include or add to itself the aesthetic element, the fine art of flavoring, the dainty garnishing of a dish. Moreover, this technique is the method of putting into practice some basic, scientific principle. To ill.u.s.trate:
The _principle_ that underlies toast-making is threefold,--
Heat evaporates moisture throughout the slice of bread.
Intense heat changes the content of the starch granules on the surface of the slice of bread to dextrin.
Intense heat, long continued, will change first the surface starch, and then all, to carbon (charcoal).
A _good technique_ will secure the first two, and avoid the third and includes,--
The selection of bread already partially dry.
The cutting of bread into slices of uniform thickness.
Regulating the source of heat.
Placing the slices firmly in a toaster, or on a fork, or evenly on a rack when toasting by gas.
Keeping the toast at a distance from the source of heat that insures a steady but not too rapid change.
Turning the toaster or the slices to cook each surface in turn and thus to make the process slower.
Stopping the process before carbon is formed and the toast "burned." (A good technique does not include sc.r.a.ping the toast!)
The _aesthetic element_ in toast-making might be a pretty shape of the slices, say triangular pieces, and a dainty arrangement. In this case and in others it is true that the result of a good technique is aesthetic, in that correct manipulation while securing the desired chemical change also develops the pleasing golden brown that makes the toast so attractive.
=The care of food materials.=--When food materials are delivered, have receptacles ready for each kind of food. (See kitchen furnishing.) Attend first to perishable foods. Wash and dry milk and cream bottles before putting them in the refrigerator. Treat eggs in the same way. This is also a good plan with lemons and other skin fruit, unless the quant.i.ty is too large, in which case they should not be put into the refrigerator. Remove wrappings from meat, poultry, and fish; wipe them with a soft cloth, dipped in salt and water, dry them, and place them in the ice box. Wash the cloth thoroughly and dry it. Fish should be covered that its odor may not affect other food. Vegetables like lettuce, celery, and spinach should be washed and picked over immediately, and the poor portions thrown away.
All semi-perishable foods should be put in a cool, dry place, and the non-perishables in their separate receptacles. (See page 20.) Do not keep anything in brown paper bags, but save these bags for other uses.
Have a regular time for inspecting and for cleaning all the places and receptacles where food is kept. Do not allow any spilled food material to remain anywhere, and do not tolerate the presence of any material, cooked or uncooked, that shows the least taint. A keen sense of smell is a good servant here.
=The processes of food preparation.=--With kitchen in order, tools ready, and food materials at hand, we are ready for the actual food preparation.
A distinction is to be made between cookery and cooking. Cookery includes all the steps necessary to produce the finished product, while cooking is the actual application of heat, only one step of the whole process, though, indeed, one of the most important and difficult. The order of procedure in food preparation is as follows: