BAKING. The art of baking consists of heating anything in an oven or fire so as to harden it, and in this sense the term is used when applied to the manufacture of bread, porcelain, pottery, and bricks. It is also applied to certain modes of dressing or cooking animal food ; thus were speak of baked meats, pies, &c. In the present article the baking of flour or meal for use as human food will alone be treated of.
The origin of baking, as of most arts of primary importance, precedes the period of history, and is involved in the obscurity of the early ages of the human race. Excavations conducted on the site of some of the numerous lake dwellings of Switzerland have resulted in the discovery of abundant evidence that the art of making bread was practical by our prehistoric ancestors as early as the Stone Period. Not only have stones for grinding meal and baking bread been discovered, but bread itself in large quantities has been disinterred, preserved by being carbonized in the first which frequently destroyed the pile-dwellings of the primitive inhabitants of the world. At Robenhausen, Meisskomer discovered 8 lb of bread, a weight which would correspond with about 40 lb of newly-baked bread. At Wangen there has been discovered "actual baked bread or cake made of the crushed corn, precisely similar to that found about the same time by Mr Meisskomer at Robenhausen. Of course, it has been burned or charred, and thus these interesting have been preserved to the present day. The form of these cakes is somewhat round, and about an inch to an inch and a half in diameter. The dough did not consist of meal, but of grains of corn more or less crushed. In some specimens the halves of grains of barley are plainly discernible. The under side of these cakes is sometimes flat, sometimes, concave, and there appears no doubt that the mass of dough was baked by being laid on hot stones and covered over with glowing ashes."—(Keller’s Lake Dwellings, Lee’s Translation, p. 63.)
The very early mention of bread in written history further bears out the great antiquity of the art of baking. Bread is first specifically mentioned in Genesis xviii. 5, when Abraham, wishing to entertain the three angels on the plains of Mamre, offered to "fetch a morsel of bread ;" and the operation of baking is immediately thereafter alluded to in the instructions to Sarah to "make ready quickly three measures of fine meal, kneed, it, and make cakes upon the hearth." At the same time, when, in the city of Sodom, Lot entertained, two angels, " he made them a feast, and did bake unleavened bread, and they did eat" (Genesis xix. 3). It may be inferred from the mention of unleavened bread that, in those, in patriarchal times, the two great classes of bread were known and used. At a period little later the art of baking was carried to high perfection in Egypt, which then took the lead in the acts of civilized life. The Egyptians baked cakes and leaves of many varieties and shapes, in which they employed several kinds of flour, and they flavoured, their bread with various aromatic ingredients. The chief baker of Pharaoh, who was in prison along with Joseph, doubtless pursued his craft in its essential features in the same as bakers do at the present day.
From ancient Egypt excellence in the art of baking traveled with the march of civilization into Greece, and the allusions to bread in works of classic authors are very numerous. In The Deipnosophists of Athenaeus mention is made of no less than sixty-two varieties of bread as known among the ancient Greeks, and minute descriptions of many of them are given. We learn from Pliny (Nat. Hist., xviii. 28) that professional bakers were first introduced into Rome at the close of the war with Perseus, king of Macedon. By the practical Romans the baking trade was formed into a kind of incorporation or guild, with special privileges and immunities attached to the calling. Public bakeries were distributed throughout the city, to which slaves were assigned for performing the heavier and more disagreeable tasks connected with the occupation. Grain was delivered into public granaries by enrolled Saccarii, and it was distributed to the bakers by a corporation called the Catabolenses. No separate mills for grinding corn then existed, the grain being pounded and sifted in the bakeries, and hence the Roman bakers were known as Pistores. As special magistrate was appointed to take cognisance of every matter connected with the management of public bakeries. The calling of the baker during the Middle Ages was considered to be one so closely affecting the interests of the public that it was put under strict regulation and supervision, and these special restrictions continued to affect the trade down to very recent times. In England, an Act of a Parliament was passed in 1266 for regulating the price of bread by a public assize, and that system continued in operation till 1822 in the case of the city of London, and till 1836 for the rest of the country. The price of bread was determined by adding a certain sum to the price of every quarter of flour, in name of the baker’s expenses and profit; and for the sum so arrived at tradesmen were required to bake and sell eighty quartern loaves, or a like proportion of other sizes, which it was reckoned each quarter of flour ought to yield. The following table exhibits the assize price of bread in London in 1814:—
TABLE
The art of making bread made its way northwards very slowly ; and even at present, in the northern countries of Europe and Asia, loaves of bread are seldom used except by the higher classes of inhabitants. In Sweden, for example, rolls are frequently seen in the towns, but loaves rarely. Towards the end of 1812 the captain of an English packet ordered a Gothenburg baker to bake for him a quantity of bread, to value of £1 sterling. The baker was confounded at so large an order, and refused to comply till the captain gave him security that the would carry off and pay for the loaves, declaring that he could never dispose of so great a quantity of bread in Gothenburg if it were left upon his hands. In the country part of Sweden no bread is make but rye-cakes, nearly as hard as flint, which are only baked twice a year. About a century ago loaf-brad was almost as rare in the rural districts of Scotland, barley bannocks and oaten cakes then constituting the universal substitutes among almost all ranks. In many parts of England it is the custom for private families to bake their own bread. This is particularly the case in Kent, and in some parts of Lancashire. In the year 1804 the town of Manchester, with a population of 90,000 persons, did not contain a single public baker. Bakers in Great Britain are now placed under the provisions of "The Bakehouses’ Regulation Act, 1863" (26 and 27 Vict. Cap. 40), a statute passed after a searching inquiry into the condition of bakehouses in London and of the persons employed in them. By this Act no young person under the age of 18 is permitted to work in a bakehouse between the hours of 9 P.M. and 5A.M., and special enactments provide for securing the cleanliness and ventilation of bakehouses, and for the regulation of sleeping apartments connected with them.
As compared with wheat-flour all other materials used for making bread are of comparative insignificance. Oat cakes still form a staple article of food in many rural districts of Scotland, and are occasionally used in other countries. They are made by mixing up oatmeal, warm water, and salt sometimes with the addition of butter or fact, into a very stiff paste, and kneading this out into a thin cake, which is first on a hot plate or "girdle," and finished in front of an open fire. Scones of barley-flour, sweet and tough, were formerly largely used in Scotland, but have now given were formerly largely used in Scotland, but have now give place to a similar preparation of wheaten flour. Rye bread, both fermented and unfermented, is largely consumed by the inhabitants of the northern parts of Europe in the poor and backward districts. Cakes of maize meal, baked like oat cakes, are consumed in some parts of the United States. The meal of various species of millets is used in Southern Europe to form bread ; and in India and China, durra (Sorghum vulgare) and other cereal grains are baked for food. Of non-cereal flours, the principal used for bread-making is buckwheat, Fagopyrum esculentum, extensively employed in Russia and Holland. The flour of pease, beans, and other leguminous seeds, are also baked into cakes ; and cassava cakes are made from the meal of the tapioca plant, Jatropha Manikot, in South America. Excepting rye, none of these substances is used for making vesiculated or fermented bread.
The grain of wheat consists of an outer husk or covering, an embryo or germ, and a central mass of farinaceous material. The outer husk is composed of several distinct layers of ligneous tissue, closely adhering to the seed, and very hard in texture. In grinding, this is detached in scales, and constitutes the chief proportion of the bran. The inner portion of the envelope is softer, and contains an active nitrogenous principle, termed cerealin, and is besides rich in fat and salts. This portion goes with the pollard or parings in the dressing of wheat flour. Towards the centre of the grain the substances becomes whither in colour and more friable in texture, so that, in grinding, the finest flour in consistence is always the whitest in appearance. By agriculturists several hundred varieties of wheat and a number of distinct species are recognized ; but in commerce the grain is distinguished as white and red, or as hard and soft wheats. There is a considerable range of difference in the proportions of their proximate constituents, hard wheats as a rule being more nitrogenous than the soft varieties ; and similarly, wheats grown in hot climate are also usually richest in nitrogen. The following analyses of two typical varieties of wheat are taken from Payen’s tables, water being neglected:—
Hard Wheat. Soft Wheat.
Taganrog. Touzelle.
Nitrogenous matter... 20_00 12_65
Starch………………….63_80 74_51
Dextrin……………….. 8_00 6_05
Cellulose……………... 3_10 2_80
Fatty matter………….. 2_25 1_87
Mineral matter…………___2_85 2.12
When wheat is ground it is sifted or dressed into a series of mill products, ranging from fine flour to bran, according to the size of the ground particles. The divisions vary in different mills and localities ; but the accompanying table—the result of an elaborate series of experiments by Messrs Lawes and Gilbert—may be regarded as a standard of the relative proportions of mill products:—
Mean Yield of Flour, Bran, &c, in 100 parts Meal.
TABLE.
The tails and fine sharps are generally passed through the mill a second time, bringing up the yield of flour to about 80 per cent. of the entire grain. As an example of mill products in practice, the following table is copied from the actual mill receipts of a Scotch miller. The quantity dealt with represents 16 quarters of wheat, weighing 63 _ lb per bushel, in all 578 st. 11 lb. The yield was—
St. lb
Fine Flour……………………………..414 0
Odd and Second Flour……………….. 23 13
Parings (Sharps and Pollards)……….. 36 12
Bran and Shellings………………….. 92 0
Waste………………………………. 11 0
The composition of flour and bran given in the understated table is the mean result of a series of fourteen analyses by Peligot:—
Flour. Bran.
Water…………………………………………………14_0 10_30
Fatty matters……………………………………………1_2 2_82
Nitrogenous substances insoluble in water (gluten)….12_8 10_84
" " soluble " (albumen) 1_8 1_64
Non-nitrogenous soluble substance—dextrin, sugar, 7_2 5_80
Starch……………………………………………….. 59_7 22_62
Cellulose……………………………………………. 1_7 43_98
Salts………………………………………………… 1_6 2_52
It is a disputed point whether dextrine or sugar exists in flour of the best quality ; but the action of heat and moisture in the baking process quickly transforms a portion of the starch into the soluble condition. In flour of inferior quality a large percentage of dextrin if usually found—a circumstance very detrimental to its bread-making qualities. A table of the percentage of gluten, obtained by Messrs Lawes and Gilbert from a large number of flours, shows a variation from 8_9 to 14_9 per cent. This gluten itself (the insoluble nitrogenous substance in flour) is a compound body, composed of three or four distinct substances; but its physical conditions of elasticity, and colour are of much greater importance to the bake than either its chemical constitution or its amount.
The varieties of wheaten bread are divisible into two great classes—Unvesiculated and Vesiculated Bread Under the first head are included such products of the art as are fired or baked without first being raised or rendered spongy by the development of carbonic acid gas within the mass, either by fermentation or otherwise. Vesiculated bread is produced when carbonic acid is either developed in or introduced in the dough, so as to permeate the mass with an infinite number of minute cavities which render the product light and spongiform.
UNVESICULATED BREAD.—The simplest form of bread, and the rudest baking, are seen in the Australian "Damper." A cake made from dough composed of flour, salt, and water, baked in the dying embers of a wood fire. The dough is laid on a flat stone, covered with a tin plate, and the hot ashes heaped around and over it, care being taken not to expose it to a heat of more than 212&Mac251;Fahr. Passover cakes, scones, and "bannocks" are prepared from a similar dough, and fired on hot plates or in ovens, and form an agreeable and nutritious food. When such dough is exposed to a high heat, so that the resulting cake is hard, dry, and resonant, biscuits (bis cuit, twice baked) are formed.
Biscuit Manufacture.—Biscuit making is a branch of trade distinct from ordinary baking, conducted under different conditions, and requiring machinery and processes peculiar to itself. Biscuits are made by a rapid and continuous process ; they can be preserved a long time, and in proportion to their place they occupy little space, so that it is practicable to sell them in markets remote from the place of manufacture. The manufacture is now conducted on a very large scale, ingenious and complicated machinery is employed in the various processes, and a large export trade in biscuits has grown up. The firm of Messrs Carr & Co., of Carlisle, was the first to originate the manufacture, and that firm still possesses of the largest and best-appointed establishments. To the partners of this firm we are indebted for much information as to the processes employed in this modern industry.
The general arrangements of a ship-biscuit factory are shown in the sectional view, fig. 1. The flour stored on the upper floor is passed down through a shoot to the flour-room, where it is sifted to free it from knots or lumps. In the making of plain water or ship biscuits, the flour is shot directly down into mixer a, on the ground floor, in quantities usually of one bag at a time, to which the requisite quantity of water, regulated by a gauge-glass, is added. The mixer is a cylindrical vessel of cast-iron, in which a series of knives or arms is kept revolving on a central axis. The revolution of these knives is sufficient to incorporate the flour and water thoroughly into a very stiff dough in about seven minutes. From the mixer the dough is delivered on a table in large amorphous masses, and it is next carried forward to the brake machine b. The brake consists of two heavy iron rollers, having generally a reciprocating motion, between which the dough is passed backwards and forwards several times till it is rolled out into a plate or sheet of uniform thickness and consistency. The sheet of prepared dough is next carried forward to the cutting and panning machine c, a highly complex and ingenious apparatus, the principle of which is shown in fig. 2. In this machine the dough is first passed between a pair of gauge rollers a, graduated to secure a sheet of any desired uniform thickness, from which it is received on an endless of felt b. On this web the sheet of dough is carried forward by intermittent to a punching apparatus e, in which moulds or cutting edges of the size and form of biscuit desired are arranged. Here the biscuits are cut out, the scrap being caught on a web d, and carried upward till it falls over in a box trough on the table e, from which it is returned to the brake machine. The biscuits are carried down the web f, and fall into tin trays, which are fed in at g by a boy, and move forward at the same rate the biscuit web travels, so that they are ready for being immediately placed on the traveling stage of the patent oven. The processes are so arranged that the oven carries forward the biscuits as quickly as they are delivered by the cutting machine, and in some cases the ovens are fed direct from the cutting and panning apparatus by automatic machinery. The patent traveling ovens are constructed from 30 to 44 feet long, and fitted with endless webs either of plates or chains. The chain webs are used for baking small and fancy biscuits, such as are placed in trays, and the plates are used for large and plain water biscuits, which are placed by hand on the travelling plates. The rates at which biscuits of different sizes and degrees of richness must traverse the whole length of the oven varies from about five to forty minutes, and the temperature of the oven has also to be modified to suit the various qualities. Both the heat and rate of motion are under easy adequate control in the patent ovens.
There is an endless variety in the form and composition of plain and fancy biscuits. In the trade list of Messrs Vicars, of Liverpool, the chief manufacturers of biscuit machinery, the names of 128 varieties of cutters are mentioned. In the making of fancy biscuits, milk, eggs, sugar, butter or lard, and flavouring essences are extensively used, and in these cases the proportions of the various ingredients are roughly mingled before being sent down the shoot into the mixer. The richest class of biscuits, the dough for which is necessarily soft, are cut out by hand labour, and fired on trays in common ovens. The dough for rout biscuits is placed in a strong metal box or chamber in which a piston is tightly fitted. The piston is moved forward by a screw, and it pushes the dough through a series of holes or dies. The dough is received on a sliding board, and is cut into proper lengths by a knife. Cracknels are made without either milk or water being used to mix the dough, eggs alone being employed for this purpose. Certain proportions of butter, sugar, and sesquicarbonate of ammonia are added to the mixture of flour and eggs, and the dough is baked in the usual way. The cracknels, when cut out, are thrown into a boiler of boiling water, and in about two minutes they float to the top. They are then fished out and thrown into cold water, and then drained on cloths, panned, and fired in an ordinary oven at a high heat. In the firing, the ammonic carbonate, being very volatile, is driven off, and the cracknel thus assumes its spongy structure. Many other varieties of biscuits are rendered light and spongiform by the use of the sesquicarbonate of ammonia, or of carbonate of soda, in conjunction with sour milk. In the firing of biscuits, not only the moisture of the dough is driven off, but a certain proportion of the water held by the flour in its apparently dry sate, so that from 10lb of flour only about 9lb of water biscuits are obtained. The composition of plain biscuit is given by Dr Parkes as follows:—
TABLE
VESICULATED BREAD.—Under this head is included such bread as is rendered spongiform in structure by the action of carbonic acid within the dough, and which is not baked hard and dry as in the case of biscuits. It includes ordinary loaf bread, pan loaves, French or Paris loaves, cottage loaves, bricks, rolls, buns, and many varieties of fancy bread distinguished by local names and minor differences of form and composition. Vesiculated bread is made in three different ways:—
1st, By the development of carbonic acid within the dough through fermentation of the flour. This is the ordinary and principal method of bread-making.
2d, By mixing the dough with water previously aerated with carbonic acid. The aerated bread made under the patent of the late Dr Dauglish is thus manufactured.
3d, By the disengagement of carbonic acid from chemical agents introduced into the dough. Dodson’s patent unfermented bread comes under this head, and the "baking powders" and "yeast powders" extensively sold consist tartaric acid, which evolve carbonic acid in presence of water.
Fermented Bread.—The manufacture of fermented or leavened bread is, as has already been hinted, of very great antiquity, and it is still by the fermentation process that bread is chiefly made. In ancient times leaven was employed to induce fermentation in dough
("a little leaven leaveneth the whole lump," Gal. v. 9), and to this day par Parisian bakers, who excel all others, in the quality of the bread they produce, chiefly use the same ferment. Leaven is simply a portion of dough, put aside from a previous baking, in which the fermentative action has reached advanced stage of activity. Yeast, however, has been used as a ferment from an early period, and it appears that it was first so employed in France. Pliny says (Nat. Hist., xviii. 12), "Galliae et Hispaniae frumento in potum resoluto, spuma ita concreta pro fermento utuntur ; qua de causa levior illis quam caeteris panis est." The use of yeast appears to have died out in France, but was revived again towards the end of the 17th century, when its reintroduction was violently opposed by the Faculty of medicine of Paris. Yeast is now used by Parisian bakers for fancy bread and pastry only.
The baking of fermented bread involves three distinct operations, which are technically denominated "setting the sponge," making the dough or kneading, and baking or firing. It will be convenient first to describe these processes as they are conducted in a London bakehouse. The first duty of the baker is to mix a ferment, which consists of a mixture of potatoes, yeast, and flour. The potatoes, in the proportion of 6 lb to a sack of flour, are boiled and mashed in a tub, and water is stirred in till the mixture is reduced to a temperature of from 70&Mac251; to 90&Mac251; Fahr. About 2_ pintsd of yeast and 12 lb of flour scalded in boiling water are then added, and the whole forming a thin uniform paste is set aside for several hours, during which it undergoes an active fermentation. Setting the sponge consists in mixing the ferment in a large trough with flour and water sufficient to make the whole into a rather stiff paste. The flour used at this stage, when "full sponge" is made, should be about one-half the entire quantity intended to be used in the "batch," and the ingredients have to be thoroughly incorporated by the workman stirring them laboriously together with his arms. The operation occupies from twenty minutes to half an hour, and when ready the sponge is covered over and allowed to rest for several hours according to the temperature at which it is maintained. Generally in from four to five hours the sponge "rises;" fermentation has been going on, and carbonic acid steadily accumulating within the tenacious mass till it has assumed a puffed out appearance. By degree the sponge gives off the gas in puffs, and the mass begins to collapse, till what was a swollen convex surface assumes a somewhat concave form, the centre being depressed while the sides adhere to the edges of the trough. The workman judges by the amount of collapse the time the sponge is ready to be taken in hand for kneading or making the dough. This process is thus described by an eye-witness:—"The batch consisted of a sack and a half of flour, nearly one-half of which had been used in making the sponge. Two men commenced breaking the sponge at 1.4 P. M. having poured the water into it, they plunged their arms in and stirred it about until it became of the consistency of thin better. At 1.10 they began to mix the dry flour with it, immediately upon doing which they were enveloped in a cloud of flour dust, their heads being bend down to within a few inches of the mass they were handling. Flour pieces of dough were splashed over the trough upon the floor. At 1.12 a third man was added. Their hair, caps, and face powdered thickly with the dust a thick cloud of which was thrown up with every movement, especially when large masses of dough, as it became a little solid, were taken up in their arms and thrown upon the rest, fresh flour being first strewn between. At 1.15 one of the men became very red and heated. The other two were very pale, and did not show any perspiration. At 1.16 the cutting off of large masses began, as much as two men could lift to place over the adjoining mass. At 1.23 the men began to pound the mass with their firsts. At 1.26 one of the pale men, who was also very thin, began to look red and hot. At 1.29, after smoothing the mass down, they began again to pound it with their first. At 1.30 it was again smoothed over, the sides of the trough scraped, and a little dry flour thrown over it. It was then considered finished.1 After this laborious process the finished dough is covered over for some time, varying from half an hour to two hours according to the temperature, during which fermentation again begins, and the mass is "proofed.": It is then "scaled off," i.e., weighed on scales in pieces of 4 lb 4 oz., if 4–lb loaves are to be made, or half that amount for 2-lb loaves ; and as rapidly as weighed it is "mounted" into the form of the loaf, when it is ready to put into the oven. Flour of good quality will take up about 17 gallons of water in course of the foregoing operations, and before into the oven the ingredients of a 4-lb loaf will be—
Lb oz.
Flour………………… 3 2
Water…………………1 1_
Yeast………………… 0 0_
Potatoes……………….0 1 _
Salt……………………0 0 _
A loaf ready for going into the oven has about half the bulk it attains during the process of firing. Batches of cottage and household loaves are packed close side by side on the sole of the oven sides of each loaf being rubbed with butter to prevent them from adhering to each other, and they are consequently crusted on the top and bottom only. Pan loaves are baked each in separate tinned pans of the form of the loaf, and Parisian loaves are baked end in long tinned pans. The firing of bread in the oven occupies from 1 to 1 _ hours, the temperature at the
FOOTNOTE (p. 253)
1 Tremenheere’s Report on Journeymen Bakers.
Beginning of the process being from 550&Mac251; to 600&Mac251; Fahr. The baker can ascertain if the oven is at a proper temperature by throwing a little flour on the sole of the oven, which ought to turn to a light brown colour. Ovens in London are usually built of brick, with a sole only 2_ inches thick ; in Scotland stone is used, the sole being from 10 to 12 inches thick, and the oven consequently retains heat much more effectually.
In Scotland the systems of using ferments is not generally practised as in London, some of the varieties of yeast of barm being mixed directly with the flour. In some localities the system of setting "quarter sponge" is adopted, in which the sponge originally prepared contains only one fourth of the flour to be used. To this, after an interval, of about twelve, hours, more, flour and water are added, which brings it up to half sponge, and about two hours thereafter the mass is ready for making the dough. In Paris, where bread-making is carried to the highest perfection, leaven, as has already been mentioned, is the fermenting agent employed. This consists of a portion of dough laid aside from a previous baking in a uniform temperature for seven or eight hours, during which it swells and acquires an alcoholic odour. This, termed "the chief leaven," is taken and worked up with flour and water to a firm paste double its original mass, when it becomes "the first leaven." After an interval of six hours the amount is again doubled, forming the second leaven. The "complete leaven" is formed by doubling the size of the second leaven, and the proportion the complete leaven bears to the finished dough is about one-third in summer and one-half in winter.
Sound flour yields from 90 to 94 4-lb loaves per bag of 280 lb, some "strong" flours giving even a greater quantity of bread. A table of experiments, conducted by Messrs Lawes and Gilbert, gives a mean result of 135_2 of bread from 100 of flour ; and in the observations of a large number of English and French authorities quoted by them, the ratio of bread to 100 of flour varied from 127 to 150. The following table gives the mean of 25 analyses of the bread of London bakers by Dr Odling:—
Water…………………….43_43
Organic matter…………...55_26
Mineral matter of ash………1_30
Percentage of ash in dry bread………..2_30
" nitrogen in new bread….1_26
" " in dry bread…..2_22
The bakers’ standard of excellence of flour, apart from the question of colour, is the weight of bread it will produce of a proper dryness and texture. The "strength" of flour in this respect appears to depend much more on its condition than on absolute percentage of its constituents.
Panary Fermentation.—It would be altogether out of place in this paper to refer to the conflicting theories as to the cause of fermentation in organic substances. The so called panary fermentation in bread-making is a true alcoholic fermentation, and whether induced by yeast or leaven the result is precisely the same. The gluten of the flour is the fermenting agent, and it is stirred into activity by contact with a glutinous body already in an active condition, which may be either yeast or leaven. In this condition it exerts a fermentative influence over the sugar which may either have existed previously in flour, or which is at least immediately developed in it by the influence of moisture. The active gluten splits up each molecule of sugar into two of alcohol, two of carbonic acid, and one of water, and consequently an infinite number of minute air bubbles are developed throughout the fermenting mass. The following equation : C6H14O7 = 2C2H6O+2CO2+H2O.
Carb. Hyd. Oxy. Carb. Hyd. Oxy.
1 molecule of Grape Sugar… 6 14 7
2 molecules of Alcohol……. 4 12 2
2 " __ Carbonic Acid…2 … 4
1 " Water ……… … 2 1
___________ 6 14 7
As the evolution of carbonic acid and alcohol proceeds, the sponge gradually swells, the little bubbles coalesce and enlarge, rising through the tenacious mass till the surface is reached, and then the carbonic acid bursts out and the dough begins to fall. This process would go on a considerable time, but the alcoholic fermentation would soon pass into an acetous fermentation and the sponge would become sour. When acetous fermentation ensues, as not unfrequently happens in baking, it may be remedied to some extent by the addition of bicarbonate of soda to the sponge. The late master of the mint, Dr Thomas Graham, was the first to demonstrate the presence of alcohol in fermented dough, and he thus described his experiment:—"To avoid the use of yeast, which might introduce alcohol, a small quantity of flour was kneaded, and allowed to ferment in the usual way to serve as leaven. By means of the leaven a considerable quantity of flour was fermented, and when fermentation had arrived at the proper point, formed into a loaf. The loaf was carefully enclosed in a distillatory apparatus, and subjected for a considerable time to the baking temperature. Upon examining the distilled liquid, the taste and small of alcohol were quite perceptible, and by repeatedly rectifying it, a small quantity of alcohol was obtained, of strength sufficient to burn and to ignite gunpowder by its combustion. The experiment was frequently repeated, and in different bakings the amount of the spirit obtained of the above strength was fond to vary from 0_3 to 1 per cent. of the flour employed." Although the temperature of the oven drives off that amount of the spirit, fermented bread is yet found to retain a proportion of alcohol, as much as from 0_221 to 0_401 per cent. having been found in different specimens of baked bread. Speaking in 1858, Dr Odling estimated the amount of alcohol thrown out into the atmosphere from the bread baked in London as equal to 300,000 gallons of spirits annually. Many years ago a patent was secured by a Mr Hicks for collecting and condensing the alcoholic fumes from baker’s ovens, and a company was formed for working the invention. After an expenditure of £20,000 the attempt had to be abandoned, not from any failure to obtain the spirit, but because the bread baked in the process was dry, unpalatable, and unsaleable
When what is termed "whole wheaten flour"—that is, the entire substance of the grain, excepting only the outer bran—is baked, it is known that the resulting loaf is of a dark brown colour, sweetish in taste, and liable to be somewhat heavy and sodden. The brown colour was at one time supposed to be due to the presence of bran particles in the flour, and in 1846 an American, Mr Bentz, invented a process for removing the outer cuticle of wheat before grinding, it being supposed that the flour so prepared would yield a loaf of white utilizing a larger proportion of the substance of the grain than is commonly used. To the astonishment of experimenters, however, the bread made from such flour was found to have the colour and other characteristics of whole wheaten bread. The subject was investigated by an eminent French chemist, M. Mège Mouriès, who found that the peculiar action of whole wheaten flour was due to the presence in the outer part of the seed of a peculiar nitrogenous body, to which he gave the name cerealin, and which is closely allied in composition and action to the diastase of malt. Cerealin exerts a peculiarly energetic influence on starch, transforming it into a brown adhesive mixture of dextrin and sugar. He showed that when the fermentative action of gluten preponderates, the result is the formation of the products desired by the by the baker—carbonic acid and alcohol ; when the influence of cerealin prevails, lactic fermentation ensues, and dextrin, sugar, and acid substances are formed, which it is the object of the baker to avoid. Several methods of avoiding this deteriorating influences of cerealin, and at the same time securing the use of the maximum of flour, have been put in operation by M. Mège Mouriès. The process now in use at the Boulangerie Centrale de l’Assistance Publique (the Scipion) in Paris, for the preparation of the flour and baking white bread with the whole of the mill products excepting the bran, he thus describes:—"The corn is moistened with from 2 to 5 per cent. of water saturated with sea-salt, and at the end of some hours the exterior coverings only become moist and tender. The grain is then thrown between nearly closed millstones, and 70 per cent. of flour is obtained without cerealin, plus 10 to 14 per cent. of meal. This is bruised between light stones, and separated by winnowing from the grater part of the husk remnants. To prepare the bread, all the leaven is made with flour at 70 per cent., and the meal is added to the soft dough last of all ; as, in spite of the small amount of cerealin which it will contains, it will not produce brown bread, because at that time the length of incubation is not sufficient to change it a leaven. Thus white bread is produced containing al the farinaceous part of the wheat."
It not unfrequently happens that flour of good colour, and unexceptionable chemical composition, fails to yield a dough which will rise by fermentation, and the loaf from which is sweet, solid, sodden, and adhesive. Wheat that has been badly harvested, or which in any way has been allowed to sprout, has part of the gluten changed into the form of diastase, which, like cerealin, changesd starch into dextrin and sugar. The gluten of flour which has been dried at a too high temperature, and of flour which has been kept in a damp situation, is modified and acts in the same manner. If dough with an infusion of malt, it yields a result exactly the same as that above described. It is to guard the starch of inferior flour against this deterioractive influence that a proportion of alum is used by many bakers of second-class bread. Alum has the power of preserving starch to a large extent from the metamorphic action of altered gluten, diastase, or cerealin, and of producing from an inferior flour a loaf of good texture and colour. The use of alum is regarded as an adulteration, and heavy penalties have been imposed on its detection ; but its estimation in bread is a process of the greatest difficulty, and authorities are by no means agreed as to its deleterious influence. Other mineral salts have a similar protection power on the starch of inferior wheat, and lime-water has been successfully employed in place of alum. To this also it is objected by some that the addition of lime renders the valuable phosphatic salts of flour insoluble by transforming them into phosphate of lime.
Aerated Bread.—When carbonic acid, instead of being generated by fermentation within dough, is separately prepared and incorporated with flour and water, aerated bread is produced. The system by which this is effected was invented by the late Dr Dauglish, and aerated bread has been manufactured under his patent since March 1859. The system is now in operation in all the principal towns in the United Kingdom, and it appears to be steadily gaining in public favour.
The Dauglish apparatus (see fig. 3) consists of the following parts:—1st, a generator A, in which carbonic acid is evolved from chalk by sulphuric or hydrochloric acid ; 2d, a gas-holder, in which the carbonic acid is stored for use after being purified in through water ; 3d, an air pump, for pumping carbonic acid from the gas-holder, and forcing it into the water vessel and mixer ; 4th, another air-pump, for withdrawing atmospheric air from the mixer before the aerated water is admitted ; 5th, a water vessel B, a strong cylinder of copper capable of withstanding a pressure of 100 lb on the square inch, and of sufficient size to contain water fro a full charge of the mixer ; attached to this water vessel there are gauge-glass C, and a pressure gauge D, for indicating the pressure of gas as it is pumped in ; 6th, the mixer E, a globular vessel of cast-iron, capable of bearing high pressure, through the centre of which an axle runs, fitted with iron kneading-arms extending to the circumference of the vessel. The pumps and the revolving arms within the mixer are worked by steam power. In order to make a sack of flour into dough, a lid at the top of the mixer is opened, and the flour passed down into it through a spout from the floor above. The lid of the mixer is then fitted tightly on, and the air within it exhausted by the pump. The requisite quantity of water, about 17 gallons, is drawn into the water vessel, and carbonic acid is forced into it, till the pressure amount to from 15 to 25 lb per square inch. The aerated water is then pass dint the mixer, and the mixing arms are set in motion, by which, in about seven minutes, the flour and water are incorporated into a perfectly uniform paste. At the lower end of the mixer a cavity F is arranged, gauged to hold sufficient dough for a 2-lb loaf, and by a turn of a lever that quantity is dropped into a pan ready for at once depositing in the oven. The whole of these operations can be performed in less than half an hour. When 4-lb loaves are to be baked the lever has simply to be twice turned. At another part of the lower end of the mixer is placed a pipe G, with a stop-cock, by which dough intended to be fired as Paris bread, on the sole of the oven, is drawn off and weighed before being placed in the oven. The pressure of gas within the mixer is sufficient to force out the whole of the dough, which, immediately on being liberated, swells up by expansion of the gas confined within the tenacious mass. Currant loaves and various kinds of fancy bread are made by the aerated process by placing the necessary ingredients in the mixer along with the flour.
The advantages claimed for Dr Dauglish’s process are:—
"(1.) It does away entirely with fermentation, and with all those chemical changes in the constituents of the flour which are consequent upon it.
"(2.) It avoids the loss consequent upon the decomposition of the portion of starch or glucose consumed in the process of fermentation, estimated at about from 3 to 6 per cent.
"(3.) It reduces the time requisite to prepare a batch of dough for the oven, from a period of from eight to twelve hours to less than thirty minutes.
"(4.) Its results are absolutely certain and uniform.
"(5.) It does away with the necessity for the use of alum with poor flour, and the temptation which bakers are under to use it with all.
"(6.) It has the recommendation of absolute and entire cleanliness, the human hand not touching the dough or the bread from the beginning to the end.
"(7.) The journeymen are relieved from a circumstances most destructive to their health—that of inhaling the flour dust in the process of kneading. …
"(8.) It will produced a healthier condition of the baking trade, and thereby diminish to a great extent the inducements which lead to the extensive system of fraud now practiced upon the public by the production of adulterated and inferior bread.
"(9.) It will effect an immense saving in the material from another source, namely, by preventing the sacrifice of at least 10 per cent. in the nutritive portion of the grain, hitherto lost as human food by the method of grinding and dressing necessary in the preparation of flour for making white bread by fermentation.
"(10.) Together with the preservation of this large proportion of the entire quantity of wheat converted into flour, there is also the important result of the proportion preserved (the cerealin) being a most powerful agent in promoting the easy and healthy digestion of food."
It is objected by opponents of the Dauglish system that the product is not really bread, but only an artificial product resembling bread. It is held that the process of fermentation has a specific influence on the constitution of bread, beyond its mechanical effect of rendering the mass spongy or porous. One of the chief hindrances to the more general used of aerated bread is the fact that is is, a compared with fermented bread, insipid and tasteless. In practice, the public have not hitherto derived any advantage from the alleged economy of manufacture, and the suitability of inferior and cheap flour for the process. Although fermented bread is hurtful in some conditions, it is not easy to supplant well-made fermented loaves in general public estimation, and aerated bread can scarcely be said to have hitherto had a fair trial, as with the necessarily expensive machinery a large trade is necessary in order to return a fair profit on the capital invested.
Unfermented Bread.—Under this head is included such bread as in vesiculated by means of carbonic acid evolved from chemical substances introduced in the making of the dough. In writing the article on "Baking" for the supplement to the fifth edition of this Encyclopaedia, published in 1816, Professor Thomas Thomson of Glasgow stated that the only end served by fermentation was the generation of carbonic acid gas, and that this might be accomplished by the use of hydrochloric acid and bicarbonate of soda. About 1842 Mr Henry Dodson commenced to manufacture bread on this system, and obtained a patent for his process. He used hydrochloric acid and bicarbonate of soda in such proportions that while, by their reaction, they liberated sufficient carbonic acid to aerate the dough, they formed chloride of sodium or common salt enough for the bread. Liebig, in his Familiar Letters, says regarding this system:—"Chemists, generally speaking, should never recommend the use of chemicals for culinary preparations, for chemicals are seldom met with in commerce in a state of purity. Thus, for example, the muriatic [hydrochloric] acid which it has been proposed to mix with carbonate of soda in bread is always very impure, and very contains arsenic." The sesquicarbonate of ammonia is also used as a source of carbonic acid in vesiculating bread, and it, on account of its highly volatile nature, is entirely driven, off in the process of baking. A great amount of private or domestic baking is conducted on the same principle, butter milk and bicarbonate of soda being used for mixing the dough in making "scones." In this case the lactic acid of the milk combines with the soda, liberating carbonic acid. The baking powders and yeast powders which are sold, and the so-called self-raising flour, all depend for their action on the mixture of bicarbonate of soda with some organic, acid, such as tartaric or citric acid.
Baking Machinery and Ovens.—The art of baking, although it is the most important of all industries connected with the preparation of human food, is one which is still carried on in the most rude and primitive manner. While modern inventions and the progress of improvement have changed the conditions under which nearly all arts and manufactures are conducted, the baking of bread is still conducted as it was during the palmy days of ancient Greece. The nature of the processes necessary for the preparation of bread, the limited time it will keep, and the consequent impossibility of storing the product or sending it any considerable distance, tend to keep the trade in the position of a limited and local handicraft. It is, therefore, not a pursuit which attracts capitalists, and master bakers are mostly in the position of small tradesmen, without either the inclination or ability to invest money in expensive machinery and fittings. In the case of biscuit baking the conditions are quite different, and it, as has been seen, has developed into a great manufacture, with elaborate and complex machinery and the most perfect mechanical appliances. Many forms of machine have been proposed as substitutes for the rude and laborious manual labour—always unfavourable to health, and sometimes not very cleanly—involved in baking. Many of these machines admittedly produce better bread than can be made by handwork, and that at no inconsiderable saving of material and time, but the necessity of either steam or water power for their effective working greatly restricts their use.
The two processes to which machinery has been successfully adapted, are the mixing of the sponge and the kneading of the dough. Attempts have been made to mould loaves by machinery, but these have hitherto failed; nor has the endeavour to fire bread in traveling ovens yet been practically successful. A great variety of kneading machines have been suggested and used, since the first of such an implement in Paris upwards of a century ago. The various plans upon which such machines have been constructed will be seen in the accompanying illustrations. Fig. 4 is a form of dough-making machine in common use. It consists of a trough or box, the lower portion of which is semi-cylindrical, hung on a spindle, with a series of iron crossbars revolving inside. It is made to be worked by either hand or steam-power, and of various sizes, as required by bakers. In this machine the whole of the operations connected with setting the sponge, breaking the sponge, and mixing the dough, are performed. The gearing is arranged to give a fast motion for setting the sponge, and a slow motion towards the close of the dough making, when it is desirable to draw out the mass in order to give it a "skin," or smooth superficial texture. A worm-wheel, working in toothed gearing, tilts over the machine when the process of kneading is complete, and the dough is then conveyed to the scaling and moulding table. Fig. 5 represents a kneading-machine, of a highly approved form, used in the great Scipion bakery of Paris, the invention of M. Boland. Externally it is like the former, and it is also geared to move at two rates of rapidity. It has further an adjustment by which the force of the motion is increased while its rate is diminished. The main peculiarity of M. Boland’s pétrin méchanique consists in the form of the revolving blades inside the trough. These blades are so arranged that they operate when in motion somewhat like alternate screws, and so toss backward and forward the dough was it is thin and lift and draw it out when stiff, passing it to each side of the trough alternately. An entirely different form of kneader is seen in fig. 6. This also is of French origin, the invention of M. Deliry-Desboves of Soissons (Aisne). Its construction and operation are thus described:—"The trough is a cast-iron basin, which turns on a vertical axis. The interior is provided with a kneader, shaped like a lyre, which first works up the dough and then divides it during the entire period of operation. Two other implements are also used, of a helical form, to draw out and inflate the dough in all directions, part by part, as is practiced in kneading by hand…The baker in charge can regulate the paste without stropping the mechanism. The water and leaven are first introduced, the trough is then set to work, the ‘workers’ employed to manipulate the dough are put in gear, and the leaven being diluted and flour added, the kneaders are also put in gear. After the lapse of twelve or fifteen minutes the dough is sufficiently kneaded, and, by turning the hand wheel fixed to the screw on the vertical shaft, the three kneaders are thrown out of gear. The implement which effects the cleaning of the trough is then removed, and its place supplied by a balance-hook, by which the dough may be weighed in the trough itself. It is simply necessary to turn the basin on its axis as required, until the whole of the dough is weighed."—(Villain, Etudes sur l’Exposition de 1867.)
The fourth form of mechanical kneader we shall describe is that invented by Messrs Vicars of Liverpool, who are extensive makers of all forms of machinery connected with bread and biscuit making. This a machine (fig. 70 consists of two vertical shafts, carrying radial arms. These arms pass each other in opposite directions, so that, in addition to a tearing action on the dough, which the knives have on passing each other, they have a screw action, pressing the dough down on one side and up on the other. The vessels containing the dough are made of wood, of an oval form, to correspond with the action of the machine. One considerable advantage connected with Messrs Vicar’s machine is, that any number of troughs can be worked by the same pair of mixing shafts, as the troughs are movable, and are raised to, or lowered from, the blades of the mixer by means of frictions wheels and spur gear. A baker can thus have several troughs containing sponges in different stages of advancement, all mixed by one pair of shafts, and all in their turn being made into dough by the same shafts.
Much thought and skill have been expended in the endeavour to effect improvements in the ordinary form of a baker’s oven, but hitherto no plan has been devised which produces bread of a quality superior to that fired in the oven which is commonly used. A baker’s oven of the common description is a low vaulted chamber, about 10 feet long, by 8 feet wide, and 30 inches high. It is built and floored of stone or brick, and has a small door in front by which the moulded dough is put in and the loaves withdrawn. At one side of this door, in the extreme corner, are placed the furnace and fire-grate, opening into the oven, and at the opposite corner, the smoke flue by which smoke escapes from the interior. The heat is by this arrangement carried throughout the entire oven, and when the temperature is sufficient the fire is withdrawn, the shut, and the dough is quickly introduced on a "peel," or long wooden shovel. Various efforts have been made to effect the heating of ovens by fire external to the chamber itself, but they fail to produce that radiation of heat which is found essential to good baking. Perkin’s hot-water oven form some time met with favour in Great Britain, and a modification of it was employed in France.
On this system the oven is heated by superheated water, conveyed from a stove through closed pipes, which are coiled round the entire interior of the oven. This oven has the recommendation of perfect cleanness, and the temperature in it is easily regulated ; but it is costly in construction, and the method has not commended itself in practice. Among ovens heated from the exterior, that of M. Rolland takes a high place for ingenuity and novelty of construction. Its characteristic peculiarity consists in the possession of a revolving sole, which not only allows the easy introduction and withdrawal of the bread, but the bringing of the different parts regularly and uniformly under the influence of the heat applied. The revolution of the sole is accomplished by a handle worked from the front of the oven ; and besides this rotatory motion the sole can also be raised or lowered so as to bring either the upper or under side of the bread close to the heat as desired. The heating of M. Rolland’s oven is effected by means of flues, which pass radially under and over the revolving sole. The chief objection urged against this form of oven is, that the air within it becomes too dry, which detracts from the flovour of the loaves fired in it. The use of the Vienna oven is general in Germany, and is extending in Paris for the baking of small or Vienna bread. It is egg-shaped in form, with an inclined sole, a very small aperture, and a low roof.1 Its average internal dimensions are 12 feet in depth, 10 feet wide, and 18 inches high. It the best of these ovens glazed tiles are used for the sole. The inclination of the sole facilitates the filling and emptying of the oven ; and the confined space of the interior retains a large proportion of moisture, which gives a fine colour to the crust and flavour to the crumb of the bread.
Qualities of Bread.—The process of baking changes the structure of the crust or outer part of a loaf, and, according to Reichenbach, develops in it a substance termed assamar, which he says has an influence in retarding the waste of tissue. It does not alter the starch of the crumb or internal part, only swells the granules, and by the induced sponginess of the mass renders it readily digestible. Well-baked bread should have a yellowish-brown crust the crumb should be uniform in texture, permeated with minute cavities, and without "eyes" or large air-cells. The colour of the crumb, unless in the case of whole wheaten bread, should be white ; it should be free from acidity and sourness. It should keep sweet and eatable for several days ; and when stale it will be found to become soft and pleasant by again heating it in an oven, after which, however, it changes. According to Dr Frankland’s determinations, "1 lb of the crumb of bread, if digested and oxidized in the body, will produce an amount of force equal to 1333 tons raised 1 foot high. The maximum of work which it will enable a man to perform is 267 tons raised 1 foot high. 1 lb of crumb of bread can produce, at the maximum, 1 7/10 oz. of dry muscle or flesh."
The adulteration of bread, and its detection, are treated under the heading ADULTERATION, vol. i. p. 170. (J. PA.)
FOOTNOTE (p.258)
1 The Vienna oven is figured in Knapp’s Technology, vol. iii. P. 192.