Bread Manufacture

BREAD MANUFACTURE. In bread making, as in other industries, the aim of modern development is to make the process wholly automatic. Nothing is more desirable than that this ideal should be attained, for where handling of the material can be dis pensed with it is certain that economy in production must be the result, whilst from a hygienic point of view the benefits are ob vious. An authority states that "the doughing machine without doubt gives the greatest ease to the workman, the greatest peace of mind to the owner, and the greatest satisfaction to the con sumer," and there is no doubt that even in smaller bakeries econ omy may be effected by even a partial substitution of hand labour by machines, of which the range is sufficient to meet all needs. The process of bread making may conveniently be divided into four sections—namely, flour handling, dough making, loaf making and baking; and although detailed attention must be directed to the completely automatic plant, for the most part the machines involved are none the less applicable to bakeries which are only in part automatic.

Flour Handling.

Handling of the flour entails blending, sift ing and weighing. The machines used for blending are either con tinuous in action or work on the batch principle. In the former the hopper of the machine is divided by partitions and the various flours fed into the compartments, at the bottom of which are ad justable feed rollers which can be controlled to deliver the requi site quantity of flour. It is claimed that such blending machines are efficient but it is doubtful whether any blend can be perfect and regular unless made in a batch machine. This type is similar in action to that of the universal kneader and each batch of flours is thoroughly mixed in it before being allowed to pass out to the elevator, which carries the flour from the blender up to large hoppers where the different mixtures are stored. A sifting machine is fitted below the storage hopper which serves the purposes of removing fluff or refuse, breaking up any lumps and thoroughly aerating the flour. The spiral brush sifter is an ideal machine for the purpose. The flour is fed into a chamber in which a spiral brush works against a semicircular sieve. This machine is rapid in action, easily cleaned and noiseless. The sifter delivers the flour into an automatic weigher. This machine is adjusted like the ordinary platform weigher, and as it discharges it automati cally cuts off the supply of flour from the sifter. In large plants, where there are two or more storage hoppers, travelling mecha nism allows the weigher to be moved to a position underneath any one hopper. An arrangement suitable for smaller bakeries com prises a blending machine, sifter and fixed weigher to serve one kneading machine. From the weigher the flour discharges direct into the kneading machine and is ready to be made into dough.

Dough Making.—Pure water at the right temperature for dough making is secured by using a tempering tank. Such tanks, of which the inside is either tinned, galvanized or of copper, are fitted with hot and cold water supplies, any temperature being thus easily obtained. A thermometer and gauge glass enable the temperature and quantity of the water within the tank to be seen at a glance. In bakeries where the process includes the making of a sponge, a sponge mixer is used. This consists of a dough mixer in which the materials are stirred together by means of horizontal blades carried on a revolving vertical spindle, the latter being raised clear of the mixer when mixing is finished, and the sponges are then allowed to rise in troughs. The kneading machine has long been the most familiar mechanical unit in the bakehouse and dates at least to 1760 when a Frenchman, Salignac, devised a model in which harrow-shaped arms, mechanically operated, mix the dough in a trough. The Boland machine, which dates from about the middle of the i8th century, was also of French origin and was probably the first which efficiently replaced the work of human arms. It consisted essentially of a trough in which re volved a pair of blades operating in the manner of alternate screws. This machine was adopted widely in other countries than France and was one of the first to be used in the British isles. Amongst the modern kneading machines which are suitable for making various types of dough is that known as the Universal. The body of the machine is a metal trough in which two blades of special shape revolve side by side on horizontal axes. The base of the trough is so shaped as to follow the path of the two arms so that no particle of dough can escape thorough kneading. The machine can be tilted easily either by hand or by power, without stopping the arms, so that the discharging of the finished dough into the dough truck is simply accomplished. The "Viennara" dough kneader is also widely used. In this the dough is made in a round pan standing on a platform which revolves about a vertical axis. The kneading is effected by an arm, T-shaped at the end, which reaches over and into the pan. The end of the arm sinks into the dough, travels across the pan and then rises again. As the pan is itself revolving, fresh dough is repeatedly brought within reach of the arm. In this way the dough is very gently and continuously stretched and folded. When the kneading is finished the pan is wheeled away for proving, a dough truck in this case being unnecessary, and afterwards returned to the machine for "cutting back." In a second type of this machine the revolving pan is not movable, but has a hinged door through which the dough can readily be discharged when kneading is complete.

Loaf Making.—The loaf making process is begun by division of the dough into pieces of suitable and uniform size. Until the year 1896 this was invariably done by hand, but at that time the first automatic dough divider was put on the market and this machine marked a very substantial advance in the mechanical equipment of bakeries. The success of these machines depends largely upon the amount of punishment which the dough receives during the operation of dividing, for, if it is treated too severely, the after effects are serious and will be reflected in the finished loaf. The division is effected by pressing the dough into cylinders, of which there may be one, two, or three, in accordance with the output of the machine, and which are adjustable in size so that the correct weight of dough may be included each time they are filled. In the United States, the number of cylinders is usually rated 2, 4 and 6. The contents of the cylinders are automatically ejected and the pieces of dough fall on to a travelling band and are carried forward. Great importance attaches to the actual method by which the cylinders are filled and this varies in differ ent models. In a widely used type the dough is fed into the hopper and by means of a weighted ram the necessary force is applied to press it into the cylinders. The pressure is adjustable to suit different types of dough and it is said that the punishment inflicted upon the latter by this method is reduced to a minimum. "Handing up," "balling up" or "rounding" in order to restore uni formity to the pieces of dough after treatment in the divider nec essarily follows. This was formerly performed by hand, a very unhygienic operation, but is now carried out successfully by ma chines of which the "conical" and "flexible" types are well known. The former consists of a revolving cone-shaped table with grooved surface for gripping the dough, around which is a stationary spirally-shaped trough supported from above. The pieces of dough are fed into the trough at the base of the cone and the latter in revolving works them up to the top, to be discharged on to a travelling band. As the piece of dough ascends it is forced against the side of the trough and undergoes a screw-like motion which makes it uniform throughout and ensures stretching of the skin in every direction. At the delivery end of the trough the slope is de creased, with the result that the "tail" of the piece of dough is "tucked in" and it rolls off the table practically spherical. The principle underlying the action of the "flexible" moulder is iden tical with that of the "conical" machine, except that the conical surface is replaced by an inclined moving table composed of metal laths carried on chains and so forming an endless belt. The mould ing troughs, which in this case may be two or more in number, are straight and are adjustable in size to suit different weights of dough and varying degrees of working. Handling of the dough after it leaves the handing-up machine has been made unnecessary by the advent of the automatic swinging tray prover. The pieces of dough coming from the hander-up fall on to trays and travel into the proving chamber, which is warmed to the required tern perature and supplied with moist vapour to prevent a skin from forming on the loaves. The trays, carried on chains, move through the prover by a circuitous route devised to save floor space and the speed is adjustable to give the correct time of proving. The damp heat within the prover necessitates regular and thorough cleaning and the suspended trays are easily removable for this purpose. The loaves on coming out of the prover are tipped on to a travelling band ready for the final moulding machines. These are similar in operation to the handing-up or preliminary mould ing machines, but are fitted with a splitting device for cutting the loaf in two when making cottage bread and with a shaping device for use with "tin" bread. A final prover completes the loaf-making process and the loaves are then ready for the oven.

Bread Baking.—In early times the oven, which was a flat baking space built in brickwork, was heated internally by wood or coke. Externally heated ovens followed, in which the baking cham ber was surrounded by flues leading from furnaces fired with coke or coal. A marked step forward was, however, taken when about the middle of the 19th century the Perkins steam pipe oven was introduced. Rows of sealed iron pipes containing water are placed at the crown and sole of the oven. The pipes project outside the oven and the projecting ends are heated. The steam produced in the pipes is much superheated and the temperature of the oven is by this means readily raised to 450-500° F. This mode of heating produces a steady but not a flash heat, and the oven can be used continuously with the minimum of attention. The old method of charging the oven with the hand peel has been superseded in mod em machine bakeries by the draw plate, or the Peel or travelling oven in the United States. The draw plate is mounted on wheels and is drawn out of the oven, charged with loaves and then returned. Decker ovens in which one baking chamber is built over another are used in some cases. It may be said that the problem of the completely automatic plant for baking "tin" bread has been solved by the production of the swinging tray travelling oven with which is combined a swinging tray automatic final prover. The loaves leave the final moulder and are deposited on the trays which pass continuously through prover and oven. The empty baking tins move back on the trays over the top of the oven to the feed end of the prover, when they are charged afresh. The bread is not handled even on leaving the oven for it passes next to a swinging tray cooler and is then automatically wrapped in paper for deliv ery. A notable development in oven construction is the travelling plate oven heated directly by gas. This oven can be included in the wholly automatic bread-making plant and can be used for baking all types of bread. (R. T. C.) Commercial baking in the United States is a large and growing industry. It ranks second among the food and high among the manufacturing industries. In 1927, 18,129 baking establishments employing 171,995 wage earners used $693,236,163 worth of materials and manufactured goods worth Of the total production 50.3% was in the form of bread and rolls, 17.6% biscuits, crackers and buns, 16.4% cakes, 4.4% pie and other pastries and 11.3% other products. In addition to using 38,782,58o bbl. of wheat flour and 2,103,509 bbl. of rye and other flours, the baking industry used 789,238,721 lb. of sugar, 450,689,325 lb. of butter, lard and other shortenings, milk and eggs valued at $53,546,320 and millions of dollars worth of yeast, malt, syrups, salt and other essential bread ingredients.

During the period 1921-28 many wholesale bakeries were con solidated and large organizations now operate chains of plants, in some cases covering the entire country. This joining of effort and production has not reduced the field covered by the retail baker, nor will bread monopolies ever be possible, for the baking of bread and cake is essentially a local industry. In the manu facture of biscuits and crackers, however, which are sold in package form under conditions which protect the products from deterioration, large-scale production and distribution over wide areas is possible. The consolidation of bread and cake plants is limited to operating control and the products are still sold within a restricted area. The quality of baked products is steadily im proving. This is due both to the use of better materials and formulae and to the development of sanitary methods of pro duction and handling. The use of enriching materials such as whole and skimmed milk has improved the character of bread and its nutritive value. The idea that bread from white flour is innutritious is now recognized as erroneous.

Arrangement of Plant.

Improved bread and cake quality is secured through the improved processes and machinery used in the modern bakery. In the development of the industry the bakery has grown from a single floor to a building several stories high. The flour purchased in car-load quantities is stored on the upper floor where it is matured or aged for several months be fore it is delivered to the mixing and sieving machines where it is blended en route to the automatic weighing devices on the mixing-room floor below. Water of definite temperature is added to the weighed flour in the mixer together with weighed amounts of yeast, sugar, salt and in most cases condensed or dried milk. The dough made from these materials is placed in large troughs each holding i,000 lb. of dough and sent to the dough or fermenta tion rooms where it undergoes a process of rising or fermenting for several hours. During the development of the yeast the dough is punched or kneaded several times to release the gas generated by the growing yeast plant and to develop the gluten of the flour under ideal conditions. The dough is then taken from the troughs and passes through automatic dividers which cut out pieces of uniform size for making i lb. and 1 i lb. loaves. The pieces of cut dough are passed on to a machine called the "rounder-up" which produces shape and form. The balled-up dough then slowly passes through a proofing chamber which is kept at a uniform temperature and in which the dough lying in slowly moving trays again expands under the influence of the growing yeast. From this point it passes to moulding machines which roll and shape it to forms to fit the bread pans in which it enters the oven for baking.

Motive Power.

The modern bakery is electrically equipped. Every operation which can be performed by machinery is mechanical and the power is usually supplied by electric motors which are a part of each machine. In the development of elec trically driven mixers, special devices have been installed which not only make every operation mechanical but also remove the possibility of injury to the workmen.

Ovens.

The modern bakery demands a type of oven in which the heat can be quickly and uniformly applied and into which the dough can be loaded and the baked bread removed with no loss of time. This need has resulted in the building of travelling ovens in which the hearth moves forward from the loading end to the exit where the baked loaves are delivered in a never-ceasing stream. Other types of travelling ovens convey the pans con taining the dough through a uniformly heated chamber, delivering them finally at the initial point where the same workman who loads the travelling trays removes the baked bread.

Fuel.—Coal, coke, gas, oil and electricity are used in firing modern bake-ovens, the type used being determined chiefly by the cost per unit quantity of bread baked. Where electricity is cheap it is the ideal fuel. Travelling ovens are usually gas-fired under systems which give an automatic control over the gas burned and heat obtained. The earlier types of ovens in which wood, coal and coke are used as fuel are rapidly giving way under the development of processes of heating which are automatic, dustless and cheap.

Wrapping and Delivery.

Sanitary legislation and develop ment of more hygienic practices in handling food supplies have compelled the wrapping of bakery products so that they are fully protected against dust, dirt and contamination by handling. As the baked loaves leave the oven they pass to a conveyor which delivers them to travelling racks on which they are cooled to room temperature. When thoroughly cool the loaves pass to automatic wrapping machines which envelop them in parchment or paraffin paper and seal them in an air-tight package. They then go to the shipping-room where they are packed in wood or metal baskets or in more modern practice in large cardboard cartons for shipment to distant points by truck or express. The products intended for local delivery are placed in specially built delivery wagons; the usual practice of distributing bread from the wholesale bakeries is through the retail grocer who purchases bread daily from a number of companies and in turn delivers it still in its original wrapper to the housewife.

Modern Operation.

Every operation in the modern bakery is automatically controlled and mechanically registered. The number of revolutions of the mixer is predetermined; the tem perature of the water which makes the dough is thermostatically controlled ; the heating of the dough in the process of mixing is held down by chilled air or brine-cooled mixer walls; the tem perature and humidity of the dough room is fixed, the speed of the divider, rounder, proofer, moulder, travelling oven, cooler and wrapping machine is so synchronized that lost motion or wasted time in any operation is impossible. Indeed, in a decade baking has become fully mechanized. The craft worker is unnecessary. Mechanics to run the machines, chemists to buy the ingredients and prepare the formulae, technicians to apply them to actual shop practice, have taken the place of the craftsman baker who less than a generation ago was indispensable to the making of bread. (H. E. BA.)