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weight in the dough, and a barrel of hard-wheat flour will make several pound loaves more than a barrel of soft-wheat flour. The weight of the dough and the size of the baked loaf are largely determined by the quantity and quality of the gluten. One hundred pounds of flour will make about 160 pounds of dough and about 140 pounds of bread. The flavor of the bread depends to a great extent upon the gluten and oil of the flour. These two compounds give the desirable "nutty" character so prominent in hard-wheat bread.
At the present day, first-class bakers generally use but one grade of standard flour for making bread. Every barrel of such flour is numbered at the mills where it is made, and if the quality should happen to be inferior, a report is made to the mill, and from the number of the barrel the mill determines the date when the flour was milled, its composition, and whether other similar complaints have been made concerning the same flour. The difficulty is thus located and remedied. Flour of the first-class standard grades costs from 10 to 25 cents per barrel more than other flours which are often just as good, and which are frequently used, although less reliable.
Yeast.—The making of leavened bread requires the use of yeast, a fungous plant. Three forms of yeast have been used in making bread: Brewer's yeast, which is that used by brewers in malting; German yeast, also called dried or compressed yeast, which consists of sporules only, and contains little moisture and no gas; and patent yeast, which is a thin watery liquid prepared from an infusion of malt and hops.
Mechanical Processes.—The most primitive method of making bread consisted merely in soaking the whole grain in water, subjecting it to pressure, and then drying it by natural or artificial heat. Perhaps the simplest form of bread and the rudest baking of modern times are found in the Australian "damper." Dough composed of flour, salt and water is made into cakes, which are baked in the dying embers of a wood fire. There have been no great modern improvements in machinery for making bread. A quarter of a century ago it was still made and baked much as it was in ancient Greece. The sponge was mixed and the dough kneaded by machinery, but as yet there had been failure to make loaves by machinery. Except in the formation of loaves, perhaps, there seem to have been no marked improvements during the last 25 years.
The Modern Bakeshop.—The statutes generally require bakeshops to be inspected and kept in healthful condition. Each baker contracts by the year with a specialist to keep insects out of his establishment. The specialist visits the place at least once every three months whether insects appear or not. He receives a notification if but a single bug appears. His work is performed so thoroughly that it is exceptional if a bug is seen at all.
The following description is of a representative, moderately large-sized bakeshop which uses from 25 to 60 barrels of flour per day, and daily bakes from 7,500 to 20,000 loaves of bread. Each day the flour for the next day's baking is sifted. The sifter consists of a rotary brush running over a sieve, and it sifts the flour as fast as an attendant empties the barrels, about one each minute. All machinery is operated by electricity. The bakeshop is three stories high, and the sifting is done on the third floor. The sifted flour descends to a bin under the ceiling of the second floor. Under this bin, and on the second floor, is located the mixer. It has a capacity of four barrels of flour. The water, milk, lard, sugar, yeast, malt extract and salt are first placed into the mixer, and then the flour is added. Two parts of moisture are used to one of flour. Compressed yeast is used, and more is required in winter than in summer. The arms of the mixer revolve at a comparatively slow rate, about once in every two seconds, throwing the dough from side to side. The mixing operation requires 30 minutes. A large spout extends through the floor to the room below. As soon as the dough is in proper condition, the mixer is turned over, and the bread descends through' the spout to the floor below, into the large bread trough which has been rolled under the spout. In this trough it rises about three hours. Thus far no hand has touched the bread, but some handwork now becomes necessary. Enough dough is weighed for 12 loaves, which are then cut out at one operation with an air pressure machine. After the loaves are cut they are molded by being run through the molding machine, of which the capacity is theoretically 60 loaves a minute, but in practice only about 40. The loaf is molded or rolled by an endless apron underneath, which carries it along in a rolling motion, and by a fixed top-piece, which is lined with sheep's wool in order to prevent sticking. The loaf travels about three feet. This is the Corby patent. After molding, the bread is placed in pans to rise. The best temperature for this is from 70 to 75° F.
The bread is baked in a continuous oven fired by coal. The temperature for baking should be from 450 to 550° F., so that the interior of the loaf will be at the boiling point, 212° F. When baked, the loaves are tipped out of the pans upon racks to cool, after which they are ready for sale. It is by varying the proportion of ingredients, the quality of the flour, the size of the loaf, and the time of rising and baking, that each baker produces bread of a quality in accord with his own ideas. The amount of bread produced from the same flour also depends to a great extent upon such variations. Rolls are cut by a special machine, 36 at a time. They are placed to rise, after which they are shaped by hand. They rise again, and then are baked. There are also special machines for mixing and cutting cake.
Kinds of Bread.—Common or leavened bread needs no description. Unfermented or unleavened bread is of two kinds: That in which substitutes producing carbonic gas are used in place of yeast, and that in which nothing but flour and water, and perhaps salt, are used. The former, also known as a vesiculated bread, is made in three different ways: (1) Carbonic acid is developed within the dough through fermentation of the flour; (2) the dough is mixed with water that has been previously mixed with carbonic acid; or (3) carbonic acid is disengaged from chemicals introduced into the dough. Maryland, or beaten biscuit, is an interesting variety of unleavened bread. Air is introduced into the dough by means of folding or pounding. These small portions of air expand in the baking, making a porous bread.
The original graham bread was made from graham flour without yeast or any of its substitutes. The dough was left standing several hours before baking. It was heavier than ordinary yeast bread, but somewhat porous, probably owing to fermentation started by bacteria accidentally present in the flour and acquired from the air. It was sweet, and by no means unpalatable. It is now baked like common bread.
Gluten bread is made from strong flour and water. The dough is pressed and strained under a stream of water until the starch has been worked out, when it is kneaded again and baked. It gives a light and elastic loaf which is often prescribed for diabetic patients. Aerated bread, which has had considerable popularity in London, is made by a method invented in 1856. The water used is charged with carbon dioxide gas. Another form of bread that has been made is the salt-rising bread. Hot water and cornmeal are mixed into a stiff batter, which is left at blood heat until it is fermented. The ferments originally present or acquired from the air produce fermentation, which leavens the batter. A thick sponge is then made from wheat flour and warm milk in which a little salt and sugar have been dissolved. This sponge and the fermented batter are thoroughly kneaded together and set in a warm place for several hours.
Chemical Changes and Losses in Baking.—Below is given in per cents the average composition of white bread and of the flour from which it was made.
In mixing the bread, the water was added, the fat was added as butter or lard, and the ash was added as salt. The protein and carbohydrates which were lost went to nourish the yeast plant. This feeds mainly on the sugar in the dough, and in its growth gives off alcohol and carbon dioxide gas. The gas and the generated steam expand with heat, force their way through the dough, and thus lighten it. Yeast also acts as an agency to turn starch into sugar. It is the tenacious quality of gluten (wanting in other than wheat flours, however nutritive), which retains the gas in its tendency to escape. Being elastic, the gluten expands, and the bread becomes porous.
"In bread making the action of the yeast and heat results in: (1) The fermentation of the carbohydrates and the production of carbon dioxide and alcohol; (2) the production of soluble carbohydrates, as dextrin, from insoluble forms, as starch; (3) the production of lactic and other acids; (4) the formation of other volatile carbon compounds; (5) a change in the solubility of the proteid compounds; (6) the formation of amine and ammonium compounds from soluble proteids and (7) the partial oxidation of the fat. In addition to these changes there are undoubtedly many others which take place. Inasmuch as many of the compounds formed during the fermentation process are either gases or are volatile at the temperature of baking, appreciable losses of dry matter must necessarily take place in bread making. These losses are usually considered as amounting to about 2 per cent of the flour used. In exceptional cases, as in prolonged fermentation, under favorable conditions, the losses may amount to 8 per cent or more." * It is claimed that the losses need not exceed 2 per cent and that they may be reduced to 1.1 per cent. Liebig calculated that in Germany the yeast plant consumed as much food daily as would supply 400,000 persons with bread.
On account of this consumption of nutritive elements by yeasts, and on account of the uncertainty of their working, chemical substitutes were sought 50 years ago in the United States and Germany. The substitutes for yeast are easily adulterated, they must be prepared with great care in order that they may not be inefficient or harmful, and even when successful the bread is usually rather tasteless. As a consequence, they have not met with success. Another loss occurs when the bread is baked. The carbon dioxide is largely retained in the dough, but the alcohol passes off. In 1858 it was estimated that 300,000 gallons of spirits were lost annually in London from baking bread, a loss of over a million dollars. Over $95,000 were spent in an effort to devise means to save these fumes. It was given up, not on account of failure to secure the alcohol, but because the bread baked in the process was dry, unpalatable and unsalable.
In baking, the starch is rendered soluble by the heat, the fermenting growth is killed, and the gluten is solidified, so that the cavities formed by the carbonic gas retain their figure. 1 U. S. Dept. Agr., Off. Exp. Sta., Bui. 67, p. 11.