Leavening Agents

LEAVENING AGENTS FOR HOT BREAD

CLASSES OF LEAVENING AGENTS

3. As has been pointed out, the ingredients that are actually required in the making of hot breads are flour, liquid, salt, and leavening, and to give variety to breads of this kind, numerous other materials, including sugar, shortening, eggs, fruit, nuts, etc., are often added. With the exception of leavening agents, none of these ingredients requires special attention at present; however, the instruction that is given in Bread regarding flour should be kept in mind, as should also the fact that all the materials for hot breads should be of the best quality that can be obtained.

As is known by this time, leavening agents are the materials used to leaven, or make light, any kind of flour mixture. These agents are of three classes, namely, organic, physical, and chemical. The organic agent is the oldest recognized leavening material, it being the one that is used in the making of yeast breads; but as a complete discussion of this class of leavening agents is given in Bread and as it is not employed in the making of hot breads, no consideration need be given to it here. Physical leavening is accomplished by the incorporation of air into a mixture or by the expansion of the water into steam, and chemical leavening agents are the most modern and accurate of all the agents that have been devised for the quick rising of flour mixtures.


PHYSICAL LEAVENING

4. PHYSICAL LEAVENING consists in aerating, or incorporating gas or air into, a mixture that is to be baked, and it is based on the principle that air or gas expands, or increases in volume, when heated. It is definitely known that when air is incorporated into dough and then heated, the air increases 1/273 of its own volume for each degree that the temperature is increased. For instance, if the temperature of an aerated mixture is 65 degrees Fahrenheit when it is put into the oven, the air or gas will have doubled in volume by the time it has reached 338 degrees Fahrenheit. Thus, the success of aerated bread depends to some extent on the temperature of the mixture when it goes into the oven. The colder it is at that time, the greater is the number of degrees it will have to rise before it is sufficiently baked, and the more opportunity will the gas have to expand.

5. The air or gas required for physical leavening is incorporated into a mixture by beating or folding the batter or dough itself, or by folding beaten egg whites into it. If the mixture is thin enough, the beating may be done with a spoon or an egg beater; but if it is thick enough to be handled on a board, air may be incorporated into it by rolling and folding it repeatedly. If eggs are to be used for aerating the batter or dough, the entire egg may be beaten and then added, but as more air can be incorporated into the egg whites, the yolks and whites are usually beaten separately. To make the white of eggs most satisfactory for this purpose, it should be beaten stiff enough to stand up well, but not until it becomes dry and begins to break up. In adding the beaten egg white, it should be folded carefully and lightly into the mixture after all the other ingredients have been combined. Beaten egg white may be used to lighten any mixture that is soft enough to permit it to be folded in.

6. To insure the best results from mixtures that are to be made light by means of physical leavening agents, certain precautions must be taken. Such mixtures should be baked as soon as possible after the mixing is done, so that the gas or air will not pass out before the dough is baked. Likewise, they should be handled as lightly and quickly as possible, for a heavy touch and too much handling are often the cause of imperfect results. For baking aerated mixtures, heavy irons are better than tin muffin pans; also, the pans that are used should be heated before the mixture is put into them, so that the batter or dough will begin to expand immediately. Gem irons should be filled level with an aerated mixture.


CHEMICAL LEAVENING

7. CHEMICAL LEAVENING is brought about by the action of gas produced by an acid and an alkali. All chemical leavening agents are Similar in their action, and they are composed of an acid and an alkali. When an acid and an alkali are brought together in the presence of moisture and heat, the result is the rapid production of carbon dioxide, a gas that expands on being heated, just as all other gases do. In expanding, the gas pushes up the batters or doughs, and these, when baked, set, or harden, into porous shapes. In addition to forming the gas, the acid and the alkali produce a salt that remains in the bread, and it is this salt that is responsible for the harmful effect usually attributed to chemical leavening agents.

8. The first chemical leavening agents were devised by housewives themselves. They consisted of a combination of saleratus, an alkali made from wood ashes, and sour milk or molasses. The results obtained were more or less satisfactory, but never entirely accurate or certain. Later on, chemists by employing the same idea combined an alkali with an acid in powder form and produced an accurate and satisfactory leavening agent in the form of baking powder. The discovery of baking powder, however, has not displaced the use of other combinations that form chemical leavening agents, for soda is still combined with sour milk, molasses, and cream of tartar in the making of various hot breads. Therefore, so that a proper understanding of the various chemical leavening agents may be obtained, a discussion of each is here given.

9. SODA AND SOUR MILK.--When soda is used with sour milk for leavening purposes, the lactic acid in the milk is so acted upon by the soda as to produce gas. However, these two ingredients--soda and sour milk--do not make an absolutely accurate leavening agent, because the quantity of acid in the sour milk varies according to the fermentation that has taken place. For example, sour milk 48 hours old contains more acid than sour milk that is kept under the same conditions but is only 24 hours old.

The proportion of these ingredients that is usually effective in batters and doughs for hot breads is 1 level teaspoonful of soda to 1 pint of sour milk. So as to derive the best results in using these chemical leavening agents, it will be well to observe that if they are mixed together in a cup the milk will bubble and may, provided the quantity is sufficient, run over. These bubbles are caused by the gas that is formed when the acid and soda meet, and when they break gas escapes, with the result that some of it is lost. Formerly, it was the custom to mix these leavening substances in this way, and then to add them to the other ingredients. Now, however, in order that all gas produced may be kept in the dough mixture, the soda is sifted in with the dry ingredients and the sour milk is added with the liquid ingredients.

10. A point well worth remembering is that sour milk and soda may be substituted for sweet milk and baking powder in a recipe that calls for these ingredients by using 1 teaspoonful of soda to each pint of sour milk. This information should prove valuable to the housewife, especially if she has accumulated a supply of sour milk that should not be wasted. Occasionally it will be found that baking powder and soda are required in the same recipe, but this occurs only when an insufficient amount of soda to produce the desired result is specified.

11. SODA AND MOLASSES.--Although molasses, which is a product of sugar cane, is sweet, it contains an acid that is formed by the fermentation that continually occurs in it, an evidence of which is the tiny bubbles that may be seen in molasses, especially when it is kept in a warm place. Because of the presence of this acid, molasses may be used with soda to form a chemical leavening agent, and when they are combined in hot breads or cake, the chemical action of the two produces carbon dioxide. However, accurate results cannot always be obtained when these ingredients are used, for the degree of acidity in molasses is as uncertain as it is in sour milk. Molasses that is old or has been kept in a warm place will contain more acid than molasses that has been manufactured only a short time or that has been kept cool to retard fermentation.

The proportion of soda to molasses that can usually be relied on for hot breads and cakes is 1 teaspoonful of soda to 1 cupful of molasses, or just twice the quantity of soda that is generally used with sour milk. To produce the best results, the molasses should be mixed with the liquid ingredients and the soda sifted in with the dry ones. As molasses burns very quickly in a hot oven, all breads or cakes containing it as an ingredient should be baked in an oven of moderate temperature.

12. SODA AND CREAM OF TARTAR.--Some housewives are inclined to use soda and cream of tartar for leavening purposes; but there is really no advantage in doing this when baking powder can be obtained, for some baking powders are a combination of these two ingredients and produce the same result. In fact, the housewife cannot measure soda and cream of tartar so accurately as the chemist can combine them in the manufacture of baking powder. Nevertheless, if their use is preferred, they should be measured in the proportion of twice as much cream of tartar as soda. As in the case of soda alone, these leavening agents should be sifted with the dry ingredients. A small quantity of cream of tartar is used without soda in such mixtures as angel-food cake, in which egg white alone is used to make the mixture light. The addition of the cream of tartar has the effect of so solidifying the egg white that it holds up until the heat of the oven hardens it permanently.

13. BAKING POWDER.--Without doubt, baking powder is the most satisfactory of the chemical leavening agents. It comes in three varieties, but they are all similar in composition, for each contains an alkali in the form of soda and an acid of some kind, as well as a filler of starch, which serves to prevent the acid and the alkali from acting upon each other. When moisture is added to baking powder, chemical action sets in, but it is not very rapid, as is apparent when a cake or a muffin mixture is allowed to stand before baking. The bubbles of gas that form in such a mixture can easily be observed if the mixture is stirred after it has stood for a short time. When both moisture and heat are applied to baking powder, however, the chemical action that takes place is more rapid, and this accounts for its usefulness in baking hot breads and cake.

14. The price of the different kinds of baking powder, which usually varies from 10 cents to 50 cents a pound, is generally an indication of the ingredients that they contain. Powders that sell for 40 to 50 cents a pound usually contain cream of tartar for the acid, the high price of this substance accounting for the price of the powder. Powders that may be purchased for 30 to 40 cents a pound generally contain acid phosphate of lime, and as this substance is cheaper than cream of tartar, a baking-powder mixture containing it may well be sold for less. The cheapest grade of powders, or those which sell for 10 to 25 cents a pound, have for their acid a salt of aluminum called alum. Still other powders that are sometimes made up to sell for 20 to 30 cents a pound contain a mixture of phosphate and alum.

15. As baking powders vary in price, so do they vary in their keeping qualities, their effectiveness, and their tendency toward being injurious. Most phosphate and alum powders do not keep so well as the cream-of-tartar powders, and the longer they are kept, the less effective do they become. The powders that contain phosphate yield more gas for each teaspoonful used than do the other varieties. Much controversy has taken place with regard to the different kinds of baking powder and their effects on the digestive tract, but authorities have not yet agreed on this matter. However, if foods made with the aid of baking powders are not used excessively, no concern need be felt as to their injurious effect. The housewife in her choice of baking powder should be guided by the price she can afford to pay and the results she is able to get after she has become well informed as to the effect of the different varieties. She may easily become familiar with the composition of baking powder, for a statement of what substances each kind contains is generally found on the label of every variety. This information is invaluable to the housewife, as it will assist her considerably in making a selection.

16. The proportion of baking powder to be used in a batter or a dough is regulated by the quantity of flour employed and not, as is the case with soda and molasses or sour milk, by the quantity of liquid, the usual proportion being 2 level teaspoonfuls to 1 cupful of flour. Sometimes this proportion is decreased, 6 or 7 teaspoonfuls being used instead of 8 to each quart of flour in the making of large quantities of some kinds of baked foods. In adding baking powder to a mixture, as in adding other dry leavening agents, it should be sifted with flour and the other dry ingredients.

17. Although baking powder may be purchased at various prices, a good grade can be made in the home without much effort and usually for less than that which can be bought ready made. For these reasons, many housewives prefer to make their own. The following recipe tells how to make a cream-of-tartar powder that is very satisfactory:

RECIPE FOR BAKING POWDER
  • 1/2 lb. cream of tartar
  • 1/4 lb. bicarbonate of soda
  • 1/4 lb. corn starch

Weigh all the ingredients accurately. If the cream of tartar and the bicarbonate of soda are to be purchased from a druggist, it will be better for him to weigh them than for the housewife, as he uses scales that weigh accurately. After all the ingredients are weighed, mix them together thoroughly by sifting them a number of times or by shaking them well in a can or a jar on which the lid has been tightly closed. The baking powder thus made should be kept in a can or a jar that may be rendered air-tight by means of a lid, or cover.

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HOT BREADS INDEX

Hot Breads in the Diet | Principal Requirements for Hot Breads | Leavening Agents | Hot-Bread Utensils and Their Use | Preparing the Hot-Bread Mixture | Baking the Hot-Bread Mixture | Serving Hot Breads | Popover Recipes | Griddle-Cake Recipes | Waffle Recipes | Muffin Recipes | Corn-Cake Recipes | Biscuit Recipes | Miscellaneous Hot-Bread Recipes | Utilising Left-Over Hot Breads | Luncheon Menu



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