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 (H₂O). 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: