which also form part of the mechanism, serve to draw out and aerate the dough, as effectively, it is claimed, as can be done by the most skilled operative. The force of the kneading operations can be regulated without stopping the machine. A thoroughly kneaded dough can, it is said, be made in this machine in twelve to fifteen minutes.
In Great Britain the type of machine that used to be most in favour was the trough within which the kneading arms worked on horizontal axis. The trough was either open or provided with a lid. The kneading blades were variously shaped, but generally were more or less straight, and were designed to both mix and aerate the dough. In some cases the kneading blades were worked on a single axis, in others two different sets of arms worked on two axes running parallel to one another. Generally the kneader was geared to two speeds, the fast motion being most suitable for sponge setting, and the earlier stages of dough-making, while the slower motion was intended to draw out and thoroughly aerate the dough. To discharge the dough, the trough was tilted by means of a worm and worm wheel, the latter being secured to the trough. Several variations of this type of kneader are still in use. The machine known as the “Universal” kneader consists of a trough set horizontally, within which rotate on horizontal axes a pair of blades lying in the same plane. These blades are curved and are geared together by means of differential spur wheels, with the object of running the two spindles at unequal speeds. The bottom of the trough is divided into two semi-cylindrical cavities, separated by a ridge. Each blade plunges into its own cavity, and the action of these arms tends, while pressing the dough against the sides and base of the trough, to bring it quickly back towards the centre. The differential speed has the advantage of effecting a more thorough mixing of the dough, as it brings together pieces of dough which have not yet been mingled, the blades pushing the dough from one cavity to the other. To hasten the kneading process it is desirable occasionally to reverse the motion by a turn of a hand wheel on the same shaft as the two pulleys. This wheel governs all the motions of the blades. The trough, which is set low, is tilted over, when the dough is ready, by an endless chain operated by a hand winch. The effort required for this operation is very slight, as the trough is balanced by two weights. The action of tilting does not interfere with the blades, which continue rotating until stopped by the hand wheel. The Universal kneader was designed to imitate as closely as possible the action of a pair of skilled human arms and hands, but of course works at a much greater speed.
Another form of dough mixer which is extensively used consists simply of a drum made of sheet steel supported by two A-shaped standards at a sufficient height from the floor to allow a trough to be run underneath to receive the dough when ready for the moulding board. In this drum are two tight-fitting doors. The interior is fitted with no blades or knives, but presents a free cylindrical space, with the sole exception that, set not very far from the circumference, there are several fixed rods passing from one side of the drum to the other. These act as mixers of the dough. The door is opened and the flour and water poured in, whereupon the door is again fastened and the drum is made to rotate. As the rotation proceeds, the dough begins to form, and being lifted up by the revolving drum falls by its own weight. In this process, which is repeated again and again, the dough is caught by and tumbled over by the rods, which act as mixers and take the place of the revolving arms of the trough kneader. The kneading action of the rotating arms is absent, but the steady tumbling over these rods appears to have a thorough mixing effect, and the dough is discharged from the drum in good condition for moulding. The time occupied for making a dough by this apparatus varies from four to six minutes. The advantages claimed for this machine are that it consumes comparatively little power, and that there is not so much danger of “felling” or over-kneading dough as in some of the machines with revolving blades. The compactness of this rotating drum mixer, often known as the Rotary mixer, recommends it on shipboard and in other places where space is limited.
In the earlier days of machine bakeries the accurate dividing of dough, and still more the moulding of loaves by mechanical means, was considered an unattainable ideal. The first step in this direction was made by the Lewis-Pointon dough divider and weigher, which was intended for dividing and
Dough dividers
and
moulders.
weighing out dough ready for the moulding table. In an ordinary way a baker who wishes to bake a batch of half-quartern or 2-℔ loaves scales off 2 ℔ 2 oz. of dough for each loaf. The 2 oz. are a sort of insurance against light weight. The evaporation of moisture from dough in the oven is bound to reduce to some extent the weight of the baked loaf, but with normally baked bread, 2 ℔ 2 oz. in the case of half-quarterns, and 4 ℔ 4 oz. in the case of quartern loaves, is sufficient to ensure full weight. As the accurate scaling of dough requires some pains and trouble, it would be surprising if hand scaling were always accurate. The Lewis-Pointon machine can, it is claimed, be set to turn out lumps of dough of the exact weight required either for 1-℔, 2-℔, or 4-℔ loaves. The apparatus does not measure the dough by weight but by volume by an ingenious piston arrangement. The machine when first put on the market was a little complicated, but its mechanism has since been simplified. It has been successfully worked on doughs of all descriptions, ranging from the tightest to those made with 20 gallons of water to the sack. The same firm which brought out this dough divider has also produced a dough-moulding machine, which has a wide range of work. In this apparatus the dough is introduced between a trough and a revolving table at a point on the outer periphery of the latter. The order of things observed in hand moulding is here reversed, as the trough, unlike the hand, is fixed, while the table revolves around a vertical axis. This table is sharply coned, and can be made to work the dough as much or as little as may be required. In working dough for tin or Coburg loaves only one trough is used, but for cottage loaves two parallel troughs are fitted, one taking the lower and the other the upper half of the loaf. In the latter case, a single piece of dough is fed into the machine and passed through an automatic splitter, the two portions being automatically carried into the troughs and simultaneously delivered at the other side of the machine ready to be put together. With doughs which require “handing-up,” two machines may be used for moulding, the dough being automatically fed from the divider to the handing-up machine, and after a short proof passed through the finisher. But the moulding machine may also be used as a “hander-up.”
Another ingenious dough moulder, known as the Baker-Callow, works on a rather different principle. Here the pieces of dough coming from the divider are fed into the moulder by a canvas band, and are worked between a large cylindrical roller and a vertically running canvas and leather belt. To prevent pieces from dropping through, and to assist the moulding process, a smaller roller is placed under and between the cylindrical roller and canvas belt. A wooden puncher also assists in working the loaves, which are finished by being rolled between a band and a special shaped wooden moulding. This machine delivers the dough in spherical shaped pieces. If intended for cottage bread they are at once placed on the dough table at the side, and one piece is put on the top of the other ready for the oven. It is claimed the machine will deal equally well with large and small pieces at the same time, so that the tops and bottoms can be made together. Should the machine be intended for tinned bread, a special attachment is used, into which the spherical pieces are delivered from the machine and rolled into cylindrical shapes, ready to be dropped into the pan. A capacity of sixty loaves per minute is claimed for this moulder.
Ovens.—The ordinary baker’s oven is a vaulted chamber, about 10 ft. in length, by 8 ft. in width and 30 in. in height; it is constructed of brick or stone, and has a small door in front through which the oven is charged (by means of a “peel” or long wooden shovel) and the batch withdrawn. The furnace and fire-grate are often placed at the side of the oven door, but with the oldest ovens, which were heated by wood, there generally was only one door for the fuel and for the bread. Whether the furnace is heated by coal, as is usual in England, or by coke, as is often the case in Scotland, the oven mouth remains in the bakehouse itself; hence the stoking and scuffling must be carried out within the bakehouse. This is in many ways objectionable. For one thing, the fuel must almost of necessity be kept in the bakehouse itself, and it is obvious that the products of combustion are liable to get into the oven. In the old type of oven a flue was frequently placed on the other side of the furnace door, both furnace and flue being on the front of the oven. After firing the furnace, the oven is allowed to “lie down” for a certain time, and secure an even distribution of heat. The furnace and flue are then shut, and the oven charged, the batch being baked by the heat stored within the oven chamber. With ovens of this type, each batch of bread requires a separate firing. This kind of oven has undergone several improvements of detail, but the principle of internal heating, that is, of firing the furnace inside the bakehouse, has remained unchanged.
A new era in bakers’ ovens began about the middle of the 19th century with the introduction of the “Perkins” oven, a system which, with slight modifications, has persisted till to-day. In this oven the baking chamber is heated by steam pipes. The latter consist of tubes of iron or mild steel which are partly filled with water and are hermetically sealed by welded ends. The pipes are arranged in two parallel rows, the one at the crown and the other at the sole of the oven. The pipes project at one end into the furnace, which is set at the back of the oven and is usually outside the bakehouse. This is termed an externally heated oven. As the ends of the pipes get red hot the water is converted into superheated steam, which being under high pressure soon raises the chamber to baking heat, say 450° to 500° F. In an oven of this description the heat can be continuously maintained, and batch after batch can be baked without refiring. The only drawback is that a flash heat cannot be raised. In another type of externally fired oven the heat is conveyed by flues placed at the bottom and top of the oven, which discharge into a chimney. Excellent results have been attained with ovens of this kind. The distribution of the heat can be well regulated; for instance, it is quite possible to build ovens to be cooler at the back than front, an arrangement which is useful when the bread is withdrawn by means of a hand peel. As the baker has to withdraw each loaf one at a time, it is clear that the withdrawal of the batch through the oven door must take time, probably not less than half-an-hour. Hence the bread drawn from near the oven’s mouth may be underbaked as compared with that at the back of the chamber. The latter, on the other hand, may be overbaked and deficient in weight.
