Use and preparation of food

E. Soda with an acid as in sour milk or molasses. When soda is added to sour milk the acid in the milk reacts with the soda, setting free a gas, carbon dioxide. The gas can be seen escaping from the mixture in the form of tiny bubbles. We take advantage of this fact in the leavening of bread. In this case the soda should be thoroughly mixed with the dry ingredients, so when the sour milk is added the gas is released but is held in by the batter or dough. Molasses and other acid sirups, as honey and sorghum, may be used in the same way. F. Baking powders are made up of soda and an acid powder. These are mixed with starch to keep them dry. The powder is sifted with the dry ingredients of the mixture and reacts when the liquid is added. There are four general types of baking powder on the market according to the form of acid used. They are : (1) Tartrate. (2) Phosphate. (3) Alum. (4) Alum phosphate. 3. Proportions. — The amount of leavening agent to be used is based upon the amount of flour. An experienced worker who handles her materials quickly can use less than one with less experience. A. The proportions given for taking powders vary from one to two teaspoonfuls for each cup of flour. The first will be successful in the hands of the skilled worker ; the second is better for the unskilled worker or in case the batter must stand. Practically all standard baking powders contain the same amount of available gas. Some react more readily than others in the cold and so may lose their gas in the can, or lose it more readily on mixing than the powders which do not react until heat has been applied. B. AVith the soda mixtures the amount of soda to be used is based upon the amount of acid liquid. The table below gives the amount for each cup of the acid solution. Cup of acid solution; amount of soda. Sour milk scant I teaspoon Sorfe'hura 1 teaspoon Molasses S teaspoon Honey \ teasi)oon 138 USE AND PEEPAKATION OF FOOD. These products vary in acidity and so the amount of soda can only be approximated. In substituting a mixed sirup for molasses the soda should be omitted and baking powder added. In using soda and acid in recipes calling for baking powder, one teaspoon of soda is the equivalent of four to five teaspoons of baking powder, providing, of course, that tliere is enougii acid present to liberate all the gas it contains. C. Sponge cakes are the best illustrations of mixtures leavened only by mr beaten into egg whites. Each egg white is equivalent in leavening power to one-half teaspoon of baking powder. In the case of butter cakes the baking powder can be decreased by this much for every beaten egg white added. D. Steam can not be substituted for other methods of leavening. It is only applicable under special conditions. 4. Influence of type of leiivening agent on temperature of baking: Degrees. '€Utigrade. Fahi'enheit. A . Baldnct-powder mixtures , hot oven B. Sodasime as baking powder 0 . Mixturesleavened witii air, low tem perature D. Mixturesleavened with steam, high at first, then lower. E. Combination of steam with air as in butter cakes 225 225 175 240-250 190-200 437 437 347 464-482 374-392 METHOD OF DEVELOPING LABOHATORY WOKK.