Part II

Bread Making

BREAD-MAKING

THE TECHNOLOGY OF BREAD-MAKING

Trades of every description have during recent years advanced by leaps and bounds toward betterment and improvement.

Inventions and discoveries of most important nature and of stupendous results have from time to time amazed the human mind and thought.

Hand in hand with inventions and mechanical devices used in the trades are step by step reaching greater perfection, simplifying and affording more accurate results of attaining standards of excellence in finished products.

Professor Liebig once said the baking industry is one in which new methods and inventions would be very difficult of introduction, and possibly in his time he may have been right.

The reason therefore may be attributed to the disinclination of the baker of that time to break away from fixed habits, partially, as well as lack of interest manifested by the general public in the production of a commodity so necessary to human sustenance.

But all this has been changed. During the last twenty years the progress made in the baking industry in mechanical contrivances, newer practical method of hydrating doughs, and as well as the great advance made in the study of fermentation, have assumed such vast proportions so as to place this craft on equal footing with any other trade as regards progressiveness.

The watchword for the future then is “more progress,” “more convenience,” “more perfection.”

With this idea in mind, these series of talks have been undertaken, hoping that they may impress the baker as to his responsibilities, and that they might stimulate in him a desire to acquire a greater and more detailed knowledge of the technical points connected with his trade. The bakery of to-day supplies man with that important foodstuff, “Bread,” rightfully called “The staff of life.”

What other trade is there in existence that can boast of any higher ideal than this?

Pre-eminently, then, the desire should be instilled in every baker to equip himself with the knowledge of how to bring his product to such a state of perfection so that it will absolutely measure up to the standard of its title, _The Staff of Life_.

There are various branches of baking. Bread, cake, pastry and cracker baking. In these talks bread and the materials entering into bread-making only will be discussed.

Raw Materials for the Bread Baker.

In the bread baking the principal materials used are flour, water, yeast, salt, milk, oil, lard, sugar and yeast foods.

I.—Flour and Milling.

A. _The moisture of flour._ Into a glass retort place some flour, taken at random from the stock on hand. Attach to the neck of the retort a glass flask, seeing to it that the connection is airtight (Fig. 1). Heat the flour over a bunson burner gently until brown. Moisture will soon show itself, accumulating at the colder portions of the flask. The neck of the retort should be kept cool with wet cloths. In this manner all the water contained in the flour will be found in the flask.

_Ordinary dry flour contains from 8 to 18 per cent of moisture, and averages 13 per cent._

B. _Gluten contents of flour._—Knead some wheat flour with water into a dough. Lay it aside under cover for fifteen minutes; then place it in a very fine sieve and let a stream of water flow over it, working the dough all the time, until the draining becomes clear, which should be retained for further testing.

There will remain on the sieve a yellowish gray tough mass.

This is the _gluten_ which imparts strength to the flour. _Good sound wheat flour contains 10 to 12 per cent. of gluten._

The gluten of wheat flour swells considerably in water, but is not soluble.

In the dry state it is horny and brittle.

When moist it soon ferments and quickly putrifies.

Gluten is classified as an albuminoid, but is not soluble in either a weak or concentrated acetic acid solution. When boiled in a soda solution it becomes partially soluble.

On account of this characteristic it is closely allied to those albuminoids known as fibrin, which is found in large proportions in animal blood. In contrast to blood-fibrin gluten may be said to be vegetable-fibrin.

The gluten of wheat flour is not a simple body, therefore not an element, but is composed of four varieties of albuminoids: vegetable albumin, vegetable casein, vegetable fibrin and gluten itself.

A marked difference exists in the gluten of rye flour. It is difficult to wash it out. It forms a sticky gray mass and is composed of three varieties of albuminoids—vegetable albumin, vegetable casein and vegetable fibrin. Gluten itself is missing.

These three varieties of albuminoids are contained in much greater proportion than in wheat flour, but the total albuminous matter in both wheat and rye flour are contained in about equal proportions.

C. _The starches of flour._ The wash water which has been preserved from the gluten washing test will at first appear to be milky, but gradually becomes clarified. On the bottom of dish the starch which has come away from the flour with the wash water will be precipitated as a fine white powder.

_The proportion of starch in both wheat and rye flour is almost equal. The average is 64 per cent._ Fine or soft flour contains more starch than hard or coarse flour.

_Properties of starch._ Take a small quantity of the starch previously obtained from the flour and mix it with water until just milky. Place a drop of the starch water on a clean microscopic slide and put a cover glass over it and gently press it down. In placing the prepared slide under the microscope the starch cells are seen to be fairly round or slightly oval, of various sizes (Fig. 2). A little off the center a bitum is observed.

The “bitum” is a sort of nucleus or spot which is the center around which the concentric rings of starch are arranged.

If by chance some of the starch properties be resting on their narrow surface they will appear elongated. Each starch particle represents a cell. The interior of the cell contains the starch proper, and is surrounded by an external coating of very delicate fibrin or cellulose. In old samples of flour the starch shows cracks and fissures.

The starch of rye flour is but slightly different (Fig. 3), and is difficult to tell it apart from wheat starch. The particles of sound rye starch are a trifle larger.

The starch of potatoes (Fig. 4) has a peculiar pear-shaped formation with very distinct bitum and concentric rings.

The properties of the starches given should enable the baker or student with the aid of the microscope to detect any foreign starch which may have been added to flour as an adulterant.

Mix a little starch with water and divide the mixture equally in two beakers.

Heat one portion to the boiling point; the starch then forms with the water, a thick, gelatinous, somewhat semi-clear liquid. The boiling causes the interior of the cell to swell, thereby bursting the cellulose envelopes.

The structure of the starch cell has been completely disrupted. The starch becomes gelatinized.

In the other beaker after a little while the raw starch precipitates. It has completely separated itself in its original form from the water.

Upon stirring the contents of the beaker violently the starch grains do not lose their original character, but simply remain suspended for a time in the water.

When baking bread the gelatinization of the starch does not take place, because the albuminoids of the flour regulated by the heat envelopes the liberated starch after its cellulose cavern has become disrupted, and in consequence prohibits the gelatinization of the starch.

Dilute some of gelatinized starch with water, pour some of it into a test tube and add a drop of tincture of iodine; the cold solution will at once turn a deep blue. Heat the liquid gently to boiling point; the blue coloring will gradually disappear; upon cooling the liquid it again turns blue.

The action of tincture of iodine at low temperature is so intensive that the smallest particles of starch contained in any substance can be detected by its use. By means of tincture of iodine starch adulteration in compressed yeasts may be detected.

Water poured on a lump of starch is rapidly absorbed. Starch is very hygroscopic, that is, absorbs moisture readily, and furthermore, retains the absorbed moisture tenaciously. Hence flour will absorb moisture from the atmosphere. A high percentage of moisture in flour is conducive of putrifying of the gluten and albumin of the flour, rendering the flour unfit for use.

Into a small pan, which has been lightly greased, to prevent sticking, heat while constantly stirring some starch flour. It will turn brown; that is, it has been converted into dextrin. Pure dextrin is soluble in water and is largely used as a substitute for gum arabic. The same conversion occurs in bread, as the starch in the exterior of the loaf is changed into dextrin by the high temperature of the oven and forms the crust of the loaf.

_Constituents of starch._ Starch is composed of the three elements—Carbon, Hydrogen and Oxygen. The composition of starch is the same as sugar. It contains the same proportions of hydrogen and oxygen as is contained in water, namely, in proportions of 2-1 (H_{2}O). Therefore starch is a hydrate, and as these water-forming elements are combined with carbon it is called carbohydrate.

To this group of bodies, besides starch, dextrin, all kinds of sugar and cellulose are classified.

D. _Albumen contents of flour._ In a flask place 20 oz. of wheat flour and saturate with 100 oz. of cold water; shake up vigorously several times during one-half hour. Then let the flask stand for some time, after which pour the clear liquid obtained carefully into a filter paper arranged in a funnel.

This clear filtrate is placed in a beaker and heated in a water bath to the boiling point. The clear filtrate will become turbid flocculent. These flakes are caused by a substance which is soluble in cold water and which evaporates upon being heated. This substance is albumin. The albumin of flour is of the same composition as the white of an egg, and is classified under the albuminoids. Wheat flour contains 1.5 per cent. of albumin.

E. _Extractive matter of flour._ After concluding above experiment, filter the coagulated mixture. Place the clear filtrate in an evaporating dish and drive off the moisture by placing the dish in a steam bath. After some time the water will have been driven off, leaving a solid residue in the dish. This residue contains sugar, dextrin, a gum-like substance, and a small quantity of mineral salts, principally potassium phosphate.

Albuminous substances all contain the four elements—carbon, hydrogen, oxygen and nitrogen, a trace of sulphur, and some contain phosphor.

The difference between these substances and the carbohydrates is that they contain nitrogen. They have also received the name proteids, frequently called flesh formers, on account of their nutritive properties.

Sugar, dextrin and gum carbohydrates that can be extracted with water.

F. _Fat contents of flour._ Shake vigorously for some time 10 ounces of rye or wheat flour with 40 ounces of ether, to which has been added 40 ounces of pure alcohol. Heat the mixture gently to 104 degrees F., and fat globules will be seen on the surface of the fluid. This is the fat contained in flour. Rye flour contains 2 per cent., wheat flour 1 per cent. of fat.

G. _Cellulose in flour._ Flour contains more or less fibrin. In order to separate it from the flour, the extractive matters of the flour are washed in consecutive order with water, ether and alcohol, the residue is then boiled in dilute sulphuric acid. The fibrin obtained is then washed and dried. In appearance it looks like wood fiber. This substance is contained also in the gluten and in the envelopes of the starch cells. It is insoluble in water, dilute acids or alkaline. It is indigestible and has no value as a food.

H. _Ash of flour._ Take a little flour and spread it on a platinum dish and heat over a bunson burner. Continue the heating until nothing remains but a grayish white powder. This is the ash or mineral part of the flour.

These mineral substances enter into the flour through absorption from the earth by the roots of the wheat grass.

The ash of flour is mostly composed of phosphates, and are of great importance because they are bone-forming and help to build up the framework of the human body.

The Average of Analysis.

Separating the various constituents of flour is called the analyzation of flour. If in a different quantity of flour the amount of each component part is determined it is called quantitative analysis. The total amount of all constituents is always figured at 100, in order to give percentage of each constituent contained. Wheat flour contains 13.37 per cent. of water. It means that 100 oz. of flour contains 13.37 per cent. of water. Therefore 100 lbs. of flour contains 13.37 lbs. of water. The same applies to the starch item, 100 oz. of flour contains 69.30 per cent. of starch.

The total amount of each constituent of several analyses added together, divided by the sum total of the analyses made, will give the average amount of each constituent contained in the flour. These analyses must be made very accurate in order that the results obtained may be reliable.

The following table, according to R. von Wagner, gives averages, subdividing the albuminoids into albumen, gliadin, vegetable casein, cellulose and gluten:

FLOUR.

per cent. Water Albuminoids Fat Sugar Gum & Starch Fibrin Ash Dextrin Winter wheat 13.37 10.21 0.94 2.35 3.06 69.30 0.29 0.48 Spring wheat 12.81 12.06 1.36 1.86 4.09 65.88 0.89 0.96 Rye 13.71 11.52 2.08 3.89 7.16 58.61 1.59 1.44

FLOUR.

per cent. Water Albumin Gliadin Vegetable Cellulose Gluten casein Wheat flour 15.54 1.34 1.76 0.37 5.19 3.50 Rye 14.60 1.56 2.92 0.90 7.36 ——

per cent. Sugar Gum Fat Starch Wheat flour 2.33 6.25 1.07 63.64 Rye 3.46 4.10 1.80 64.28

YEAST AND FERMENTS

Mix some flour into a dough and bake it. The result will be a coarse, tough, indigestible cracker.

The flour and water product possesses keeping qualities, but can only be used as a food when soaked in a fluid.

A baked product if used as a nutriment must possess lightness and porosity and be so constituted that it can be easily digested.

For this reason yeast is required in bread making.

Yeast.

_A Gas Test._—Dissolve in a flask 2 ounces of syrup or honey in a pint of water at 140 degrees F., and add one-sixth of an ounce of compressed yeast, which has been broken up and dissolved in a part of the saccharine infusion. Seal the flask with a perforated rubber cork, pass a bent glass tube through the perforation and attach a piece of rubber hose to the glass tubing. In fifteen or twenty minutes small bubbles will be seen rising to the surface of the fluid, which will continually increase in number, until the surface is covered with a froth formation, somewhat like the head of a cauliflower.

_The fluid is fermenting._—After 1 to 1½ hours the froth forming gradually ceases and finally drops.

During fermentation lead the rubber hose attached to the generating flask into a smaller flask half filled with water. You will notice bubbles oozing from the mouth of the hose through the water. Then at once make a test by holding a lighted match into the small flask. The match will burn readily, just as it would in the air. After ten or fifteen minutes repeat this procedure and the burning match will be extinguished at once, even to the glimmer.

During the first test atmospheric air only was contained in the small flask. It required a little time for the gas of the generating flask to displace the atmospheric air, as a result of which the lighted match went out at the second test.

Another peculiar phenomenon is noticeable in connection with this test. On top of the water in the open flask the developed gas remains stationary, but can be dispersed by an air current, either created by blowing or by waving the hand over the opening of the bottle.

If we then pour some clear lime water into another small bottle and allow some of the gas from the generating flask by means of the rubber tubing to flow into the same, we will find that, after withdrawing the hose, closing the bottle with the thumb and slightly shaking the contents, the lime water turns milky.

This is caused by a combination of the dissolved lime and the gas. The latter, which we have developed, is Carbon Dioxide (CO_{2}).

By the above tests we find that Carbon Dioxide is heavier than the atmosphere, and thus remains in the bottle undisturbed by atmospheric pressure, for a time, as it combines very slowly with the air. By creating a draught, the combining with the air is facilitated.

Top and Bottom Yeast.

Remove with a glass rod, during active fermentation, a little of the froth from the saccharine infusion and wash it off with a few drops of clean water, and place a small drop of the solution upon the object glass of the microscope. At 300 to 500 magnified strength we notice that the froth consists of small round or oval bubbles, which occasionally, though seldom, are elongated. They appear singly or in groups, and often look like strings of pearls. These bubbles are yeast cells. Figure 5 shows yeast cells after five hours of propagation. Each cell has a thin covering of fibrin or cellulose; while the interior contains a soft granular albuminous substance, called Plasma, or Protoplasma.

During vigorous fermentation at a temperature of 68 to 80 degrees F., the majority of the bubbles are forced to the surface of the fluid by the action of the escaping Carbon Dioxide, and at the final stages of fermentation gradually precipitate. At a temperature of 36 to 45 degrees F. the fermentation is slower, the generating Carbon Dioxide is less active in escaping and without sufficient force to bring the bubbles to the surface. The yeast cells to a great extent grow and settle on the bottom of the generating vessel.

These characteristics designate top and bottom yeast.

Both of these yeasts are of the same species, and either can be converted into the other by the changing of the temperature during propagation. They are recognizable by a slight difference in size. Owing to the more favorable conditions during growth top yeast is somewhat better developed than bottom yeast. Compressed yeast used in bread baking is top yeast.

_Distillation Test._—After the fermentation in the generating flask has ceased, and no more bubbles rise to the surface of the fluid, test it by distillation. For this purpose we first filter the saccharine fluid to remove the yeast cells. Place the clear filtrate in a clean flask, stop it with a perforated rubber cork, and connect it by means of a bent glass tube with a cooling apparatus. Figure 6 shows such an apparatus. The vapor generated from the filtrate contained in the flask passes through the coil in the cooler, as shown in the illustration. The cooler is provided with tube connections at the lower and upper ends, which can be fitted with perforated corks, through which glass tubes may be inserted.

The lower tube by means of rubber tubes is connected with the cold water faucet, not shown in the illustration; the flow of cold water around the coil can be regulated at the faucet and drawn off at the upper tube.

In lieu of a cooler as shown, one can be constructed by leading the tube of the filtrate flask into a somewhat wider and longer glass tube, which is connected with a second bottle. The long glass tube, in this case, must be kept cool by constantly pouring cold water over it during distillation.

When all connections have been made tight, heat the filtrate over an alcohol lamp to a boiling point, the flask having been placed on a piece of wire gauze to equalize the heat. The arising vapors passing through the coil are condensed, and drip like tears into a receptacle placed underneath the cooler. This evaporating and condensing of a fluid is called distillation.

The portion of the condensed fluid coming over at the beginning will be found, if tasted, to be very strong spirits of alcohol. Light it with a taper, it will produce a large bluish flame.

As the distillation continues the spirits coming over lose gradually in strength until finally very little else but the vapors of water are condensed. Water boils at 212 degrees F., spirits of alcohol at 172 degrees F. We would therefore infer that at the beginning of distillation it is possible to recover alcohol only if the infusion was heated to 176 degrees F.

This view, however, is erroneous. The boiling point of the mixture is only slightly greater than that of pure alcohol, and the generated vapors are already at the beginning and combination of both fluids, although at first the proportion of alcohol is the greater.

We have now seen that yeast is capable of producing alcohol and carbon dioxide. This is called alcoholic fermentation.

Wine, beer, brandy and other spirituous liquors are produced by alcoholic fermentation, and the same is attributed to the raising of bread doughs.

The yeast cell in its search for nutriment consumes and changes the sugar, to facilitate growth, finally reducing it into simpler bodies of alcohol and carbon dioxide.

The chemical changes of the sugar are due to the ever-changing composition of the albuminous plasma of the yeast cell. When the plasma has lost the power to renew itself, it dies and putrefaction sets in.

Worts of sugar and diffusible albuminous solutions are ideal foods for yeast, as they readily permeate the fine, porous coverings of the yeast cells to nourish the plasma, which at the same time, by its own action, creates the requisite warmth by the dissolution of the sugars with alcohol—carbon dioxide.

The following description will illustrate how this is accomplished:

Make a drumhead, by stretching and fastening a piece of bullock’s bladder or either vegetable or animal parchment paper over a cylinder of glass. Place this in a vessel containing pure water, and pour into the cylinder a strong solution of common salt. The salt brine and the pure water are only separated from each other by the thin membrane of the bladder or the parchment. After a little while it will be noticed that the salt solution will have diffused out through the membrane until the liquid, both outside and inside the floating cylinder, has the same strength. This is called osmose, or dialysis.

In choosing its nutriment yeast is very selective. Of the carbohydrates, glucose, maltose and those of C_{6}H_{12}O_{6} group are capable of direct fermentation, and are quickly and vigorously changed by yeast. In direct opposition, we find that cane sugar, beet sugar, as well as the starch of flour, are not fermentable until chemically changed. This change is brought about by yeast itself.

The plasma of the yeast contains an albuminous substance called Invertin. As explained above, the Invertin, by dialysis, is diffused out through the cell covering and changes cane sugar and sugars of the same class, as well as part of the flour starch, into fermentable sugar, known as invert sugars.

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_Reproduction of Yeast._—During fermentation yeast nourishes and reproduces itself. The granulations of the living plasma divides itself, and with a portion of the plasma forms a small protuberance at one end of the cell; it then enters the neck, which is gradually developed by the contraction of the cell wall and forms a bud.

The neck finally closes, the budding daughter cell releases itself from the parent cell, and each are then an individual organism.

This operation is known as “budding.” Each parent cell is capable of giving off several buds in succession. The daughter cells in their turn reproduce in the same manner, and so with remarkable rapidity yeast cells multiply.

But yeast is also reproduced by spores termed “ascospores.”

In this case yeast cells do not throw out a bud, but the plasma divides itself into (usually) four portions called spores, each of which surrounds itself with a thin membrane.

These spores, when set free by the dissolution of the cellulose coverings of the parent cells, on account of their minuteness float away into the atmosphere. If by chance they drop into the proper medium, such as malt wort or flour barms, spontaneous fermentation sets in.

This is recognized by the fact of spontaneous fermentation frequently and easily occurring in the fermenting rooms of yeast factories and breweries, as innumerable quantities of spores are present in the atmosphere at all times.

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_Pure Yeast Cultures._—By the manner in which yeast nourishes and reproduces itself, we acknowledge it to be a plant of exceedingly elemental structure.

Being devoid of the green coloring matter of the plant (chlorophyll), the yeast cell is incapable of assimilating inorganic matter, such as carbon, nitrogen, ammonia and certain mineral salts, for the purpose of building up their tissues.

Yeast belongs to the family of Fungi, and on account of the peculiar manner of its reproduction is classified as “Sprouting Fungi.”

We are obliged to admit that the true nature of the yeast cell has as yet never been entirely satisfactorily explained. Some scientists are of the opinion that yeast cells are but the embryo of higher fungi development; for it is known as a fact that certain species of the sprouting fungi do not possess the faculty to incite alcoholic fermentation, while, on the other hand, some of the higher species of mould fungi possess the qualification not alone to incite alcoholic fermentation, but are also capable of ascospore formation. So much for this explanation.

It has been proven by actual results that different species of yeast produce widely different kinds of fermented liquid. These differences are recognized in the yeast cell of wine, of beer, and of the distillery, the last named being also the yeast of dough fermentation.

If the yeast cell of wine be placed in a beer wort, the fermented wort will assume a vinous flavor, and is known as maltine.

Science has shown that yeast cells are composed of groups of various species. The principal species, among others, as found in brewers’ or distillers’ yeasts, are known as Sacchoromyces Cerevisial and Sacchoromyces Pastorianus.

Both are very much alike in appearance, both incite alcoholic fermentation, but develop in a similar wort a number of widely different by-products, the analyses of which have thus far baffled the resources of the chemist. The action of these two species is readily recognized by the flavor and taste imparted to the fermented medium.

As the bouquet imparted to wine is attributed to the wine yeast cell (Sacchoromyces Ellipsoideus), characteristic of the grape juice, so the baker recognizes by the flavor of his baked product that the proper species of yeast has been employed, irrespective of the flavor which may have been obtained by other materials used in the baking.

While it is difficult to separate the various species of yeast cells, the phenomena of spore formation has led the way to accomplish it.

At a temperature of 54 degrees F., Sacchoromyces Cerevisial will show ascospore formation in 200 hours, while Sacchoromyces Pastorianus at the same temperature forms spores already in 77 hours. This difference in time of the maturing of the spore formation of the various species of yeast being known, is utilized in transferring the spore of any specific species upon culture plates of nutrient gelatine, upon which the spores develop into little colonies of yeast cells.

The healthiest and strongest appearing cell is then cut out with a sterilized platinum wire and transferred into a flask of sterilized malt wort, and the reproduction from a single cell of any given species is begun. In this manner pure yeast culture is accomplished.

In the fermenting vats growing yeasts are often contaminated by spores of undesirable species from the atmosphere, and result in producing conditions unfavorable for the purposes desired. In such cases we must resort to a pure yeast culture to re-establish the desired fermentation.

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_Manufacture of Compressed Yeast._—Compressed yeast is the result of alcoholic fermentation of malt and grain worts. As it is of material interest to the baker to acquaint himself with a general knowledge regarding the manufacture of compressed yeast, a short but clear description is given below.

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_Treating the Grain._—Malt is produced by soaking barley or other grains in water and spreading in thin layers on the floors of the malting rooms. Being moist and in consequence supplied with artificial heat, the grains begin to sprout. As the rootlets grow in size a product is being formed in the germ that has the power to convert starch into sugar. This product is called Diastase. This reaction is still clouded with a good deal of mystery, and it has as yet never been clearly defined.

We know this much, however, that some parts of the nitrogenous matter of grains are chemically changed into Diastase.

Practice teaches the maltster, by the size the rootlets attain, when the maximum diastasic strength of the malt has been reached.

The sprouting of the malt is now arrested by drying the malt in kilns at a temperature of 131 to 176 degrees F., which evaporates the moisture and kills further germination.

For malting purposes barley is mostly used, as its diastasic strength exceeds that of any other grain.

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_The Yeast Mash._—For preparing the yeast mash crushed malt and rye is employed, although other grains are used to replace part of the rye, such as corn and buckwheat.

Experience teaches, however, that the best results are obtained by the use of barley malt and rye only.

The materials are selected with great care. The water employed is boiled, the rye must be clean and free from dust, and the malt free from mould. The rye is first soaked in water and then crushed.

In 200 liters of water at 125 degrees F., 100 kg. of the grains are mixed and constantly stirred for thirty minutes, until all lumps have disappeared, the temperature in the meantime remaining constant. At this temperature the dissolving of the albuminous matters of the grains is favored, and the changing of the starches into sugar and dextrin is facilitated.

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_Saccharification of the Mash._—At the expiration of the thirty minutes the temperature of the mash is gradually increased by steam from 122 to 158 degrees F., and constantly stirred.

It has been substantiated that these temperatures are best suited for a perfect gelatinization and saccharification of the starches without injuring the diastasic properties of the malt. At the same time, a temperature of 158 degrees F., which is continued for two hours, is useful to effectually sterilize the mash by destroying the undesirable bacteria. During this time the diastase, which, as we have seen, was produced in the sprouting barley during malting, effects its function in the quickest possible manner. The result is a very sweet, lasting fluid.

In order to ascertain whether the saccharification has been complete, a small portion of the mash is filtered and tested with a drop of tincture of iodine. When the tincture of iodine discontinues to produce a blue coloring in the filtered fluid the saccharification is complete.

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_Acidulation of the Mash._—This is probably the most momentous stage of compressed yeast manufacturing, and watchfulness must be practiced, if the object be to produce a pure yeast free from all possible contamination.

The means used for this purpose is the introduction of lactic acid fermentation. The mash is covered up, occasionally the mash is stirred, but always from bottom upward, so as to bring as large a surface as possible in contact with the atmosphere (oxygen), while the mash is kept at a temperature favorable to lactic ferment growth.

The reason for this acidulation is twofold. In the first place, the lactic ferments assist in converting the insoluble albuminous matters of the grains into soluble matter. Technically, this is known as changing the albuminoids into peptones.

In the second place, lactic ferment is absolute poison for the undesirable bacteria, which may have developed, without injuring in any way the yeast cells proper, but rather has an influence for good toward them. Sulphuric acid is sometimes added to increase the acidity.

When the acidity reaches 2½ per cent. in the mash it is ready for further manipulation. Apparatuses to indicate the per cent. of acidity developed are used for the purpose of accuracy.

The acidulation of the mash having been satisfactorily completed, further operations are dependent upon the method selected to produce yeast. The older method is known as the “Vienna Process,” while the newer method is called “Aeration Process.”

The Older or Vienna Process.

_Fermentation of the Mash._—At the completion of the acidulation of the mash it is at once cooled to 77 degrees F. This is accomplished by continuously agitating the mash by mechanical means with hollow plungers that are filled with ice or cold water, and which at the same time serves to aerate the mash.

The former method of cooling the mash in shallow vats, on account of infection and introduction by and of undesirable bacteria from the atmosphere into the mash, has been generally discarded.

Fermentation is now introduced by adding a certain quantity of compressed yeast, which must be free from starch adulteration.

In a short time a head begins to develop upon the surface of the mash, which gradually grows and rises to the top of the half-filled vats. The period of fermentation depends upon the temperature of the mash as well as the density of the mash.

The higher the density of the mash, the more vigorous the fermentation.

In general, the time consumed for proper fermentation is twelve to eighteen hours.

As fermentation proceeds, the density of the mash becomes less, while the yeast cells increase, and at the same time the temperature of the mash raises.

The mash in this process contains the whole of the grains, and for this reason the head, which contains the yeast cells, and which is skimmed off as it rises, must be strained; it is subsequently washed and then pressed. In contrast to this method the newer or “Aeration Process” for the production of yeast presents entirely different phases.

Production of Yeast by Aeration Process.

This method was invented in Sweden about ten years ago, and is in use in many yeast factories to-day. A decided greater percentage of yeast yield is accomplished by the “Aeration Process.”

After the saccharification of the mash is completed, the extract called “wort” is strained to remove the husks and bran of the grains. Large vats containing a double bottom are used for this purpose, the inner or upper bottom being perforated. Spigots are attached to the bottom of the vats to draw off the “wort.” At first the extract appears opaque and is again returned to the mash. This pouring-back process is continued until the “wort” finally flows perfectly clear from the spigots. The extractive matter still adhering to the husks and bran of the grains is washed out or “sparged” with hot water.

Another way employed for recovering the clear “wort” is by means of the filter press. The percolation method, however, is preferable, as the extraction of the essential properties is more complete.

Fermentation is produced in the “wort” by adding small quantities of compressed yeast also, or by the use of pitching yeast. During the fermenting period a continuous stream of atmospheric air is forced through the “wort” by the aid of air pumps. In order to eliminate atmospheric dust and bacteria, the air before entering the “wort” filtered through cotton, and sterilized by passing it through a solution of salicylic acid. It is also necessary to distribute the air to all parts of the “wort” equally, by means of perfected tubes, which are attached to the main air pipe, branching out in various directions at the bottom of the fermenting vats, with the perforations facing downward. At the beginning the air current is very moderate, and is increased in accordance and in proportion of the yeast growth. At the final stages of fermentation the air current is again moderated. This forcing in of air, or rather oxygen, in the “wort” stimulates in an exceedingly large measure the propagation of yeast, but care is exercised in this respect, however, for if the air pressure be too strong a large per cent. of alcohol, a very important by-product, will be lost. The characteristic feature of this method, distinguishing it from the Vienna Process, is the continued aeration during fermentation, hence called “Aeration Process.”

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_Obtaining the Yeast._—Fermentation of the “mash” or the “worts” proceeds at a lively rate. In observing the “head” or froth, during the “Vienna Process,” which at first is transparent, gradually assumes a milky or of more opaque appearance, caused by enormous increasing growth of yeast cells, filling up the froth bubbles. When the cells are fully developed the fermentation may be considered finished. Practice assumes, although the assumption is not always reliable, that this stage has been reached when the “head” or froth begins to recede. The only sure method to determine proper maturity of the yeast cell is by microscopic observation.

Placing some of the froth under the object glass of the microscope, the yeast cells most appear well developed and isolated from each other. It should be the exception rather than the rule that budding cells still be visible.

Not until assured that the proper time has been reached should the skimming of the upper portion of the froth be begun. This portion of the “head” contains the so-called “pitching yeast,” and is used largely in starting new propagation.

Large galvanized perforated spoons with long handles are used to skim off the froth. Repeated observations of the froth during the skimming are made, to ascertain the condition of the yeast cells.

The yeasty froth is immediately mixed with ice cold water to arrest further fermentation. This also serves to increase the keeping properties of the yeast.

The water containing the skimmed-off matter is now run through strainers of varying sized meshes, the coarser retaining the husks and bran, while the finer meshes prevent the gummy matter adhering to the yeast cells from passing.

The strained yeast cells are caught up in vessels containing water, where they precipitate in a compact layer, and is then ready to be washed.

In order to watch the settling of the yeast, these vessels are constructed with windows so as to give the operator a perfect vision of the settling.

This operation of washing the yeast in new water and allowing it to settle is repeated several times, at which time nearly all of the impurities have been removed and excellent keeping properties have been attained.

A newer method of washing yeast has lately been introduced by the invention of a specially constructed patented centerfuge. If it be intended to mix starch with the yeast, it is usually done just after the washing has been completed.

Potato or rice starch are used. The utmost carefulness must be observed in the examination of the starches, as they frequently are contaminated with bacteria or acids, which tend to injure the keeping qualities of the yeast and very soon become unfit for use.

After the clear water of the last washing has been removed by decantation, the compact settled mass is pressed dry by hydraulic or filter press, and finally formed by specially constructed machines into pound pieces, familiar to all bakers.

The “mash” or the “wort” after the yeast has been removed contain alcohol in paying quantities, and is recovered by distillation.

One hundred kilograms of mash yields an average of 11 per cent. yeast and 28 per cent. of alcohol, if fermented according to the “Vienna Process.” The “Aeration Process” yields 25 per cent. of yeast and 18 per cent. of alcohol. The remaining grains in the liquids are much sought after for their value as desirable fodder for cattle.

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_Yeast Adulteration._—High class compressed yeast should be free from all adulterants. Most manufacturers, on account of the slimy matter of yeast, causing many difficulties in pressing, add from 5 to 10 per cent. of potato starch, claiming that it increases the keeping qualities by absorbing part of the moisture. The writer, however, does not agree with them.

Starch is undoubtedly at times added to yeast in large excess; it then becomes an adulteration; this fraud is, however, readily detected by treating the sample of yeast with iodine. For this purpose break up a little of the yeast in a test tube with some water, shake it up well and add a few drops of tincture of iodine; after standing a little while the starch will settle at the bottom of the tube in a dark blue layer.

Plaster of paris has also been found in yeast; this, besides being fraudulent, is decidedly criminal, and verily, is giving a “stone for bread.”

Nature of and Examination of Compressed Yeast.—A good sample of compressed yeast should have a creamy white color. A brownish discoloration would indicate that fermentation had been too far prolonged before skimming. It should have an odor of apples, not cheesy; neither should it have an acid odor or taste. A piece of blue litmus paper pressed against the cut of the yeast should remain neutral or at the most show but a faint sign of red; a marked change in the paper from blue to red would indicate acidity.

A microscopic view of good yeast dissolved in water should have the appearance as seen in Fig. 2, shown above. When broken it should show a fine fracture, irregularly rounded. Should it be crumbly, deterioration has set in. In lukewarm water it should melt readily, and not be sloppy to the touch. The dissolved yeast placed in a glass tube should settle slowly and evenly with the water above it perfectly clear. During this test adulteration with plaster of paris is readily detected, as it would be the first to settle out, and by carefully decanting the fluid, examination of the sediment would disclose plaster of paris.

If the solution of yeast and water does not clear itself the yeast is spoiled, and is of no use for the fermenting of doughs. It is contaminated with wild yeast and harmful bacteria, and would be instrumental in starting putrefactive fermentation, ruining the flavor of baked goods. Should we desire to ascertain the amount of starch present in an adulterated yeast, the following method is applicable:

Weigh a small beaker and a small glass rod on a very accurate scale; or, better still, on an analytical balance, and assume the weight to be 17.5 g. In the beaker place 10 g. of the compressed yeast under examination; break it up fine with the glass rod, and place the beaker in a hot water bath for several hours, weighing occasionally until two consecutive weighings are exactly equal; for instance, 21.2 g. We deduct from this the weight of the beaker and glass rod, giving us the following figures: 21.2 g. - 17.5 = 3.7 g.

The quantity of moisture evaporated out of the yeast would therefore be 10 g. - 3.7 = 6.3 g. According to the findings of Hayduck, pressed yeast contains originally 73.5 per cent. and dry starch 36 per cent. of moisture.

We now proceed to make deductions to determine the quantity of starch contained as an adulterant in the mixture. We set the example: “What per cent. of starch is contained in a mixture of yeast and starch if 10 g. of the mixture gives off by evaporation 6.3 g. of moisture, yeast containing 75.3 per cent. and starch 36 per cent. of moisture?”

Solution.—One hundred g. of pure press yeast, heated to dryness, gives off 73.5 g.; therefore, 10 g. heated should give off 7.35 per cent. moisture.

In our test the loss is but 6.3 g., consequently a deficiency of 1.04 g. This in itself indicates starch adulteration.

Starch gives off 36 per cent. of moisture; therefore, 1 g. gives off 0.36 g., and 1 g. of yeast 0.735 g. of moisture. With each 1 g. of starch addition the moisture loss is found to be 0.735 - 0.36 = 0.375 g. deficient.

In the 10 g. mixture under examination there is contained as many times 1 g. of starch as 0.375 g. is contained in 1.05 g., which is equal to 2.8 g. In a 100 g. mixture the result would be 28 g., or 28 per cent., which is the per cent. of starch adulteration in our mixture examined.

The Fermenting Strength of Yeast.

The best manner for the baker to test the strength of yeast is to take equal parts of the samples of the various yeasts, about 10 g.; dissolve in 100 g. of water at 85 degrees F., and make a dough with equal amounts of the same bread flour (about 1990 g.).

In order to prevent transferring of any one yeast sample to either of the other doughs, it is advisable to thoroughly wash the hands between each mixing. Place the doughs in glass jars of equal dimensions, and allow them to raise at an even temperature. It goes without saying that all ingredients must be weighed exactly alike, and the temperatures in all cases be the same. The yeast which gives the greatest expansion of the dough has the preference.

Another simple manner to test the strength of yeast is to drop a piece of the dough into tepid water (85 degrees F.), and observe the time consumed between immersion and when the piece of dough rises to the surface of the water. The dough which rises in the shortest time contains the strongest yeast.

Of course, in technical schools yeast strength is determined along different lines. A Hayduck carbonic acid measuring apparatus is used for this purpose, and is shown in cut (Fig. 9). It consists of two connecting glass tubes fastened against a board. The wider of the tubes has a capacity of 500 cc., and ends at the top in a narrow glass tube, to which rubber tubing may be attached, and is graduated in cubic centimetres. The other narrow tube ends at top funnel-shaped.

Through the funnel the apparatus is filled with water, colored blue to make observations easily. In order that the water may not absorb any of the carbonic acid gas, which would tend to make the test inaccurate, on top of the water in the wider tube a thin layer of petroleum is poured.

In gas generating flasks (A) a suitable “wort” and a definite amount of yeast, to be tested, is dissolved and placed in a water bath. (B) is a second flask for the next following test. (C) is a pinch-cock, which is left open so long as (D) is kept closed. The generated carbonic acid gas forces the water out of the wide tube and is caught up at (G). The yeast which has the ability to displace the largest amount of water at stated periods is considered the best fermentation inciter. Before any readings are taken the water in both tubes is brought to the same level by means of cock (E).

If care be taken to use the exact proportions of materials in each test at even temperature, reliable conclusions are obtained from each individual yeast sample.

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_Water._—Next to flour, water is the most abundant compound used by the baker. It is the great solvent of Nature. Pure water is composed of the two gases, hydrogen and oxygen, in proportions of 1 to 8. It is colorless and tasteless.

Water as found in nature is never pure. Owing to its action as a solvent, it contains bodies like lime, magnesia and potash in solution, besides air, carbon dioxide and other mineral matters. Hard water is such as contains more than seven grains of mineral salts per gallon.

The hardness due to bicarbonate of lime may be neutralized by boiling. Other mineral salts are penniment.

In general, soft water is more adaptable for bakers’ use, as hard water retards fermentation and somewhat checks the softening changes going on in the dough during fermentation.

Doughs made with hard water require to lay longer to properly mature.

It is for this reason that the baker will find it necessary at equal dough temperatures to modify his methods when using hard or soft waters to get uniform results.

It is of the utmost importance that water used in the bakery be free from organic matter that is detrimental to health, as many such organisms have a tendency to set up putrefactive fermentation in doughs.

In a broad sense, however, water that is declared fit for drinking purposes can be safely employed in bread work.

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_Salt._—Chemically known as chloride of sodium. It is produced from three different sources: Bay or sea salt, rock or mine salt, and natural brine or pit salt. Of these the refined product of natural brine or pit salt is to be preferred by bakers.

It should be dry, to insure uniform results, as wet salt contains a large percentage of water, which interferes with obtaining accurate and uniform quantities needed in the doughs.

It is added to doughs in varying amounts, from 1½ to 4 pounds per barrel of flour, and gives bread flavor and taste. When working with soft water more salt is required than in hard water. While salt gives the bread flavor, it also retards fermentation. It is especially of import by keeping in check lactic and butyric fermentation, causing sour bread. Authorities claim that salt in all proportions from 1.4 per cent. upwards retards fermentation and diminishes the speed of gas evolution, the raising of the dough.

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_Milk._—Is largely used in bread making. Dry milk on account of its convenience, has supplanted fluid milk in a large measure in the bakery.

Although not universally accepted, the writer is of the opinion that dry milk containing pure butter fat will add equal flavor to bread in which fluid milk is used.

Besides giving flavor and nourishing properties to bread, on account of its dryness it has water absorptive qualities that are of economic value to the baker.

Dry milk also contains soluble extracts that have an invigorating influence on yeast growth, i. e., fermentation, and improves and gives a better bloom in the crust of the bread.

In point of economic value, the baker should determine, by making small trial doughs, the increased volume obtained by reason of the extra moisture absorbing properties of dry milk when used in doughs.

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_Fat._—Lard, compound lard and cotton-seed oil are the fats generally employed in bread making. The use of fats effects a finer texture in the bread.

A colorless shortening assists in producing a whiter crumb, and also by coating the cells of the loaf retains the moisture of the baked bread. Doughs containing large amounts of shortening, under best and equal conditions, will stand a larger amount of proof, as part of the shortening in a well mixed dough has combined with the gluten of the flour used, allowing it to stretch further and become more elastic and still hold the increased amount of gas generated by the heat of the oven, and produces a loaf of greater volume.

Not all shortenings will produce the same effect, and the baker should experiment with small batches. The points to be determined are the effect the shortening has on the crust, volume of the loaf, as well as the color.

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_Sugar._—Among the sugar groups used in the bakery we find cane sugar, malt extracts, glucose and yeast foods.

Each of these products have characteristic effects on fermentation and doughs, and will be treated in a later paper.

DOUGHS LEAVENED BY YEAST

BY PROF E. W. HABERMAAS

There are two distinct ways of making doughs. One way is to set a sponge first, then make the dough, and the other way is to make the dough at once. The first is called a “Sponge Dough” and the second is called a “Straight Dough.” Straight dough is so called, because all ingredients such as yeast, salt, sugar, lard, water and flour are all mixed and formed into a dough. There are various reasons for making straight doughs, a few of which we will proceed to give. In the first place, it is more convenient to make a straight dough, because it does not require as much time to make as does mixing the sponge dough, because the mixing is all done at one time. Then, again, a straight dough can be taken in a shorter time than a sponge dough. By this I mean that in case of necessity the dough can be taken, in from 1½ to 2 hours after it has been made. I do not advocate taking the dough in such a short time, but it can be done, because I have done it with good results.

Straight dough requires more yeast than doughs made from a sponge, because the yeast has not as favorable a medium in which to grow, in the straight dough as it has in the sponge dough. It is conceded by some that straight dough requires a stronger flavor than a dough made from a sponge; by others that a stiffer dough is required; by others, that the finished product has a coarse texture, and that an “yeasty” taste predominates. The author made straight doughs daily for eleven years successfully. He neither made a specially stiff dough nor did his finished product have a coarse texture nor an “yeasty” taste. Sometimes when the temperature of the shop was very high or an exceptionally weak flour was sent us, then would our product have a somewhat coarse texture, but this would soon be remedied by using less yeast and reducing the temperature of the liquid used. There are advantages in using strong flour, but they are alike in the straight and the sponge dough, and they are larger yields and larger goods, but these are not the only points to be considered.

Some bakers are partial to spring wheat flour, because the yield in bread is greater than when a blend is used.

Too often is quantity preferred to quality. It seems that most bakers are working to the one end, namely, to get the flour which yields most bread. In this endeavor they are sacrificing quality for quantity.

Spring flour containing a larger per cent. of gluten than winter wheat flour naturally takes up more moisture, producing in turn more bulk, therefore more bread.

Then again the gluten in the spring wheat flour is of a tenacious character, producing a tough elastic dough. Such a dough can resist a greater gas pressure than can one made of weaker flour, and can therefore stand more proof, thus producing a larger and better appearing loaf than one made of a winter wheat flour or a blend.

If a blend is used, we will say two parts of a high grade winter wheat, and one part of spring wheat flour, and the dough is properly worked, the bread will have a fine, smooth, soft, velvety texture, and a mild, sweet taste. The loaf will not be as large a loaf as the one made of spring wheat flour, but will remain soft and moist longer than the loaf made of spring wheat flour. The reason for this is, that winter wheat flour contains a larger per cent. of natural moisture and a smaller per cent. of gluten than the spring flour, therefore it takes up less moisture, and consequently does not lose as much by evaporation in baking; thus leaving a larger per cent. of moisture in the bread.

The chemist’s test cannot decide the true baking value of a flour. A bakeshop test, made by a practical baker, is absolutely necessary to decide this matter.

The principal points to be considered when making straight dough are these: the temperature of the ingredients, the temperature of the shop, the quantity of yeast, and the quality of the flour used. If the temperature of the shop is very high, the liquid used should be cool, and the quantity of yeast should be reduced.

The most favorable temperature for fermentation is from 80 to 90 degrees Fahr., though I prefer to have the dough 85 degrees Fahr.

Before proceeding to make the dough, take the temperature of the flour and the shop, then heat the water to a temperature which will give your dough a temperature of 80 degrees Fahr. when ready. For example, if the temperature of your flour were 5 degrees Fahr., the temperature of the water would have to be 10 degrees Fahr. Now if the temperature of the shop were 70 degrees Fahr., the temperature of the water could be raised to 110 degrees Fahr. I would advise you not to get the temperature of the dough too high, but would rather that you raise the temperature of your shop. Dough chills very quickly when it is on the bench, and after a dough is chilled it will come up very slowly. When making dough in a dough-mixer, the temperature of the water should be at least 5 degrees higher than when making it by hand, because the mixers are more or less cold, while, when dough is made by hand you have the animal heat of the hands to keep up the temperature of the dough. When the weather is very warm, the temperature of the water must be changed to suit. For example, if the temperature of your shop is 90 degrees Fahr., your flour would naturally be very near the same temperature (providing it were kept in the shop), then the temperature of the water would have to be at the utmost 75 degrees Fahr., because the temperature of the dough would continue to rise while it was in the trough or mixer.

Process for Making Straight Dough.

Heat the liquid to the required temperature, then dissolve the yeast in a portion of the liquid, then, when the yeast is dissolved, add it to the rest of the liquid; then add the salt and dissolve it; then add the fats and sugar; then add the flour. (As above mentioned for uniform results it is best to weigh the flour, sugar, salt and fats.) After the flour has been added, work it into a smooth dough.

Weighing and Measuring Ingredients Used in Baking.

By Professor E. W. Habermaas.

All solids used in baking should be weighed, and all liquids should be measured accurately. Varied results and failures in baking are very often due to inaccurate weighing and measuring of ingredients. If your recipe calls for a pound of sugar, don’t use 1¼ pounds instead. Or if a recipe calls for 1 gallon of milk, don’t use ⅞ gallon instead. The author has often seen bakers use 1¼ pounds of some ingredient when 1 pound was what should have been used. Many bakers are exceptionally careless about measuring the liquids, such as milk and water. They will dip a quart or pint measure into a can of milk or into a bucket of water and draw it out on a slant, thus causing a portion of the liquid to run out. Often as much as one-fourth of a pint of milk will run out of the measure, still they will count that a full measure. This may seem a trifle, but when measuring a number of quarts or pints, it ceases to be a trifling matter but becomes a matter of vital importance. For example, you are about to make a dough of four quarts of milk or water, and you measure the milk or water as above shown. After having added the flour and you are making the dough, you will find that the dough is too stiff. This is based on the fact that you use a given quantity of flour to every quart of milk or water used, as should be the case, if you expect uniform results. You have the correct amount of flour, but not enough milk or water. Then again, the yield of such a dough would be less than it should be. Most bakers do not weigh the flour for their dough. Where this is the case, flour is usually added until the dough is of the proper consistency. So in that case the fact that the baker had not measured the liquid accurately would not necessitate getting too stiff a dough, because he has not a given quantity of flour to work in but adds it until the dough is of the proper consistency, but the yield will be less because there is less dough.

I do not approve of this method of making doughs, because the results are not uniform, and it requires more time to make the dough, because you are compelled to add more flour occasionally to get the proper consistency. Whereas, when you have the exact amount of flour and add it at once, you can proceed with dough without interruption. Then again, when you weigh the flour for your dough, you always have uniform results.

The flour, sugar, malt extract, salt and fats (if any) should be weighed, and the milk or water measured or weighed for every batch of dough, no matter how large or how small, if you would have uniform results.

One of the “hit or miss” methods prevalent in most shops is that bakers measure the water and weigh the salt, and guess at the rest. Fats, sugar and flour are seldom weighed. What are the consequences? Sometimes they have a stiff dough, sometimes a soft dough, and sometimes a medium dough. Sometimes the dough comes up too fast and sometimes too slow, owing to the consistency of the dough. Then, again, they never get the same number of loaves out of the same size batch. If the dough is too stiff, they get more than the required number, and if the dough is too soft they get less than the required number out of the batch.

In large shops such methods would not be tolerated, then why should they be tolerated in small shops? Thousands of dollars could be saved monthly in bakeshops if more accurate methods were adopted.

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When using a very strong flour you can use a little more yeast than ordinarily without fear of mincing the dough, because strong flour can stand more proof; but unless absolutely necessary, don’t use any more yeast than is required under ordinary conditions. During the summer months it is well to use more salt than during cold weather, because salt acts as a governor—it holds the dough in check and keeps it sweet.

Too much yeast creates an over-abundance of gas, and if the dough is not tough enough to withstand the pressure of the gas, it tears and allows the gas to escape; the dough then falls and loses its vitality. If this dough were “made up” into loaves, and when baked were cut in two, it would be seen that the texture would be very coarse; it would be a mass of holes, and the taste would betray a trace of lactic fermentation. This bread would not be fit to eat. Don’t allow your doughs to get too old. If a dough gets too old it loses its vitality, and when baked it will have a coarse texture and will have a sour taste. Test your doughs as follows: When the dough has set about one hour, jam your hand into it; if it begins to fall it is ready to take; if it does not fall, allow it to set about one-half hour, then try it again. A dough may be taken before it falls, but I would not advise you to make a practice of doing that. I have made a batch of bread and had it baked and out of the oven in three hours. I set the sponge at 9.30 a. m., made the dough at 10.30 a. m., and had the bread baked at 1 p.