A Treatise on Baking

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Wheat and Flour

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Chapter I

WHEAT AND FLOUR

WHEAT AND FLOUR

I. NO OTHER GRAIN CAN REPLACE WHEAT IN BREAD MAKING

Wheat justly deserves its reputation as the world’s most essential cereal,—for wheat flour is the indispensable body of bread, the Staff of Life. No other grain can take the place of wheat in bread making. This is due to the fact that wheat is the only cereal known to man containing the proper combination of glutenin and gliadin which in the presence of water combine to form gluten, that elastic, tenacious substance which holds the gas produced by the action of yeast on sugar. This gluten is the necessary skeleton or framework of bread forming the sustaining walls of the whole cellular structure of the loaf. In view of this, every one connected with the baking industry should understand in a general way some of the fundamental points regarding wheat.

II. HISTORY OF WHEAT

The exact origin of wheat is unknown, but we do know that it was grown by primitive man in pre-historic times. Back in the stone age, wheat was harvested, crushed by hand, moistened with water and baked on hot rocks. Down through history to the present day,—the cultivation of wheat has been the world’s foremost agricultural pursuit, until,—now the magnitude and importance of wheat growing needs no explanation.

III. THE CULTIVATION OF WHEAT

Hundreds of years of selective cultivation and “crossing” has resulted in the many varieties of excellent wheat grown at the present time. The climatic conditions, soil, type of seed and time of planting determines the character of wheat secured. Wheat is grown in temperate regions but does not thrive in the tropics, except at high altitudes. The United States produces nearly one-quarter of the world’s wheat crop.

IV. SIMPLE CLASSIFICATION OF WHEAT

A great number of different systems of classifying wheat has been proposed. In the past, however, wheat was usually designated in two classes:

(A) Winter wheat which is sown in the Fall in localities having a winter climate mild enough to permit the plant to survive the winter, and

(B) Spring wheat which is sown in the Spring in localities having a rather severe Winter.

In the United States,—Winter Wheat is usually harvested in the latter part of June and in July, and Spring wheat during late July, August and September.

In general, Spring wheat grown East of the Rocky Mountains represents hard wheat, and Winter wheat may be classified into two groups—soft winter and hard winter.

V. GOVERNMENT CLASSIFICATION OF WHEAT

The U. S. Federal classification of wheat is as follows:

• Hard Red
• Spring Durum
• Hard Red Winter
• Soft Red Winter
• White
• Mixed Wheat

Durum wheat possesses a high gluten content but yields a yellowish flour not suitable for breadmaking and is used mainly for macaroni.

VI. HARD AND SOFT WHEAT

In view of the fact that there are hard and soft varieties of both Spring and Winter wheat, and because of the crossing of the different varieties of wheat and varying climatic conditions, the designation of Spring and Winter wheat has lost much of its former significance. The extension of the Winter wheat territory into the semi-arid regions of the West has resulted in the production of more hard winter wheat.

From a practical standpoint, it would be much clearer to merely place bread wheat into two classes:

(a) Hard Wheat

(b) Soft Wheat

Hard and soft of course, are relative terms, and there is no exact line of demarcation between them. In general however, hard wheat yields flour which is relatively hard to the feel, while soft wheat flour is relatively soft to the feel. Hard wheat is characterized by a relatively high content of gluten components, while soft wheat is relatively lower in gluten components.

VII. NORTHWESTERN AND SOUTHWESTERN WHEAT

Wheat is frequently designated by the location of the country in which it is grown, such as Northwestern and Southwestern. Today, excellent flour for bakers’ use is secured both from the Northwestern and Southwestern sections of the country.

Soft wheat is grown in various sections of the country and there is of course, quite a wide range of the different types of wheat coming under this general classification.

VIII. DESCRIPTION OF A GRAIN OF WHEAT

A grain of wheat is a plump, oval shaped body having a distinct fold or crease along one side.

GRAIN OF WHEAT—HIGHLY MAGNIFIED

(After Jago)

This microscopic section of a grain of wheat shows the different parts of the wheat kernel.

As shown in the accompanying diagram, the beard of the wheat consists of tiny vegetable hairs or fuzz, projecting from one end of the grain. The wheat berry proper consists of three main divisions, which are as follows:

A. BRAN

This is the tough, woody coat, protecting the interior of the wheat, and consists mainly of fibre and mineral matter, together with some protein and traces of fat. The bran consists of two main parts, namely, the outer bran and inner bran, each of which has several distinct layers, which are as follows:

1. Outer Bran

(a) cuticle OR epidermis. This is the outside layer of woody fibre.

(b) epicarp. A layer of cells just inside the Epidermis.

(c) endocarp. A layer of relatively large and round cells.

2. Inner Bran

(d) episperm OR testa. This is a thin layer of cells directly beneath the Endocarp and in “red” wheat contains most of the coloring matter of the bran.

B. ENDOSPERM

The endosperm represents the bulk of the wheat berry and is located inside of the branny coat. It consists of two principal parts:—

1. Aleurone Layer

This section of the endosperm consists of a layer of cells roughly rectangular in shape and located directly beneath the bran. The aleurone cells contain some soluble protein, mineral matter and fat. At one time the aleurone layer was erroneously spoken of as the “gluten” layer. However, the aleurone layer does not contain the components of gluten. In the process of roller milling, the aleurone layer finds its way into commercial bran.

2. Starch and Gluten Portion of the Endosperm

This is the main part of the endosperm and represents that portion of the wheat berry which goes into wheat flour. It contains starchy granules, varying slightly in size and shape, which are surrounded by gluten components. The greater quantity of gluten bodies are located in the outer part of the Endosperm. The best quality gluten, however, is secured from the center of the grain.

C. GERM OR EMBRYO

As shown in the diagram, this section of the wheat berry is located at the lower end of the kernel. It consists mainly of fat and also some protein of a non-gluten type, and sugar. The germ is actually the seed portion of the wheat berry from which sprouts originate, if the wheat berry is allowed to germinate. Both the bran and germ are practically eliminated in the process of milling of wheat in order to secure white flour which merely represents the Endosperm reduced to a fine powder.

IX. MILLING OF WHEAT

A. HISTORY

The art and science of the milling of wheat have developed progressively from the discovery of wheat to the present time. In the early days, wheat was ground between handstones. Later, wind and water mills came into existence.

Today the modern milling process is the latest word in milling efficiency, and through this process the excellent quality of flour now on the market is made possible.

B. PRE-TREATMENT OF WHEAT BEFORE MILLING

Before the actual milling of the wheat takes place, a very careful pre-treatment of the grain is necessary.

Utmost care is exercised by the modern miller in the selection of his wheat, and cleaning of the same prior to milling. Preliminary samples of wheat are first received and carefully tested. The wheat is then selected and purchased. It is carefully screened, scoured, washed and dried. The thoroughly cleaned wheat is tempered by subjecting it to properly controlled temperature and moisture conditions. Frequently various types of wheat are carefully blended to insure the production of a high quality uniform flour. Equal precaution is taken throughout the entire subsequent milling process, so as to produce the finest type of flour from the wheat.

C. MILLING OF THE WHEAT

To completely explain the milling of wheat would require volumes but in view of the importance of wheat flour to all bakers, a very brief description of the average present day milling process is in order. While various modern millers may use a slightly different process and different types of milling machines, the roller system of milling is most generally employed today.

1. Break Rolls

The cleaned and tempered wheat is first passed thru a series of break rolls which are corrugated or grooved. These break rolls revolve at different speeds, breaking up or cracking the wheat kernels into coarse pieces, and enabling most of the bran and germ to be separated from the interior of the kernel. The bran is collected and disposed of as animal feed. The remainder of the cracked kernel, which is in the form of coarse meal is termed: “Middlings.” In the modern milling process there are about five “breaks,”—middlings being removed after each “break.”

2. Separation and Purification of Middlings

The Middlings are separated into several streams by sifting, sent to the purifiers where the dust and light bran particles are removed by an air blowing arrangement,—the Middlings being passed through sieves of silk cloth.

3. Reduction Rolls and the Separation of Flour Streams

The purified Middlings are then passed through a series of reduction rolls, which are smooth faced. This process causes any portion of the germ remaining in the Middlings to “flake out” because of the oil or fat which it contains, thus enabling the germ to be separated, as well as any fibrous material still present.

The Middlings which have been ground and re-ground are separated into various streams of flour by sieving and bolting. The bran particles collected at the tail of the middling process and which do not pass through the sieves are termed “shorts” and go into feed. Low Grade and Red Dog are names given to certain milled portions of the Middlings which are eliminated from the high grade flour in the process of milling. These go into the mixtures sold as animal feed.

X. FLOUR

Thus we see that white wheat flour may be considered as the interior portion of the wheat berry reduced to a fine powder, from which the bran, germ and coarser particles have been removed. The degree of perfection of modern milling depends on the completeness with which the bran and other parts of the wheat are eliminated from the Endosperm and in pulverizing the Endosperm to the proper degree.

A. TYPES OF FLOUR

The different types of white wheat flour used in baking are often characterized in a general way by the type of wheat from which they are milled, such as Northwestern wheat flour, Southwestern wheat flour, Spring and Winter wheat flour, or simply hard and soft wheat flour.

B. YIELD OF FLOUR FROM WHEAT

The yield of flour secured from any given wheat depends upon the nature and quality of the wheat itself and the process of milling employed. In modern milling practice, 100 pounds of cleaned wheat will usually yield about 70 to 76 lbs. Middlings to be ground into flour of various grades and about 24 to 30 lbs. feed.

C. MEANING OF PERCENTAGE SEPARATION

In milling and baking circles, flour is often designated by a certain percentage separation, such as 80% separation or 60% separation. Frequently, the word “extraction” is used instead of the term “separation.”

This percentage is not based on the weight of the original wheat used, but on the weight of the total flour secured after practically all of the bran and feed have been removed. Thus, if any particular stream or combination of streams of flour obtained in the milling process represented 75% of the total flour, this would be characterized as 75% separation flour. By the careful combination of the various streams of flour at the mill,—the miller can secure from a given wheat any particular percentage separation flour desired down to the shortest separation Patent. Short Separation flours represent a lower percentage separation or more highly refined flour, than flours of longer separation.

THE MILLING OF WHEAT INTO FLOUR

The above diagram is a crude representation of the general separation of the various grades of flour-and does not show the exact system of the separation of flour streams

D. SPECIFIC GRADES OF FLOUR FROM ANY GIVEN WHEAT OR BLENDS OF WHEAT

Flour is milled into different grades in order to secure perfect elimination of fibre, germ or other impurities, from the finely pulverized portion of the endosperm of the wheat berry.

There exists much confusion concerning just what is meant by certain terms used to designate the various grades of flour, such as Fancy Patent, Baker’s Patent, etc. Such terms mean very little to the consumer as they are not standardized, and interpreted differently by different millers. The important point in this connection is actually the value of any certain flour for baking purposes, and this of course, is measured by the yield and quality of bread secured. However, there are certain general terms used to designate—within rather wide limits—various grades of flour of interest to the baker. These are as follows:

1. Straight Flour

This represents all of the flour produced from the middlings, or in other words all of the flour produced from the wheat in the milling process, after the removal of the bran and feeds. Therefore a Full Straight is termed 100% extraction flour, and represents a combination of all streams suitable for flour.

2. Patent Flour

This represents the most highly refined flour,—from which all of the “Clears” have been separated. A First or Short Patent represents a patent flour of the shortest separation. A Second or Long Patent represents flour not quite so highly refined as the Short Patent since it is of longer separation.

3. Clear Flour

This represents the remainder of the flour produced after the patent portion has been removed. Thus, if all the patents and clears of any one milling process were combined they would represent “straight” flour. Usually clear flours are designated in two groups, namely: First Clear, which is the more highly refined portion of the clear, and Second Clear, which is the remainder of the clear when the First Clear is removed.

Clear flours are darker in color but higher in the amount of gluten components and ash contained than Straights or Patents. Patent flour is very light in color and comes from the most central part of the wheat berry. Such flour is lower in ash and amount of gluten components, but very high in gluten quality. Straight flour naturally stands in between patents and clears in regard to ash, gluten components and color.

E. PRESENT DAY FLOUR IDEAL FOR BAKERS’ USE

Too much significance should not be placed on the names usually applied to various grade flours—for such terms are used differently by various people. Today, the modern miller, by careful selection of wheat, by judicious blending and efficient up-to-date milling methods, is placing at the disposal of the baker, uniform flour of the highest quality which is ideally adapted for the baker’s requirements. This obviates the necessity of a baker carrying too many different grades of flour on hand. There is no doubt the miller makes his blend in the most conscientious way, and is in the best position to make the blends required. The comparative value of flour for baking purposes can be determined by means of simple tests; though whatever tests we may employ, the baking test is the final and only completely satisfactory one. Certain flours may possess certain desirable characteristics, and other flours may possess other characteristics, which are equally important to the baker. By proper blending, the exact type of flour ideally adapted for any baker’s particular needs,— may be readily secured.

While the ash and protein content of any flour furnishes an indication of its grade,—its baking value is best shown to the average baker by a baking test.

Hard wheat flours with a suitable protein content and well milled represents in general, bread flours which produce a good quality of loaf if properly handled.

For cakes, a flour of less protein is used, such as a soft winter wheat patent. For crackers, softer varieties of winter wheat flour are used.

F. UNITED STATES STANDARDS FOR GRAIN MEAL-FLOUR AND GRAHAM FLOUR

The United States Department of Agriculture has published the following definitions and standards:—

1. Grain is the fully matured, clean, sound, air-dry seed of wheat, maize, rice, oats, rye, buckwheat, barley, sorghum, millet or spelt.
2. Meal is the clean, sound product made by grinding grain.
3. Flour is the fine, clean, sound product made by bolting wheat meal. It contains not more than fifteen per cent (15%) of moisture,* not less than one and twenty-five hundredths percent (1.25%) of nitrogen, not more than one per cent (1%) of ash, and not more than one-half per cent (0.5%) of fibre.
4. Graham Flour is unbolted wheat meal.

*By moisture is meant the loss in weight resulting from drying in accordance with the vacuum method of the Association of Official Agricultural Chemists.

G. COMPOSITION OF WHEAT AND FLOUR

It is impossible to state any one definite composition of wheats or flours used for bread making which will apply in all cases, due to the unavoidable variations in the yearly wheat crop which of course is materially affected by the climate, soil, etc.

However, an approximate composition of an average bread wheat and patent flour is given below:

Outside of the moisture, the wheat and flour constituents shown above are each made up of a great number of complex compounds, and the chemistry of flour covers a wide variety of subjects which are continually being investigated by those interested in milling. However, the main factors of interest to the baker in connection with the composition of flour are briefly described as follows:

H. NATURAL MOISTURE IN FLOUR

Flour can very readily take up moisture or lose moisture, depending on how it is stored. The moisture of flour usually ranges from 10 to 14%. The U. S. Government has fixed 15.0% as the upper limit for the moisture content of flour, when determined by a Vacuum Oven Method of the Association of Official Agricultural Chemists. This moisture limitation of 15% determined in this manner is practically equivalent to the former moisture limitation of 13 1/2% as determined by the water oven method, if flour has lost moisture after storage for a considerable time, this loss can usually be made up by a corresponding added absorption when mixed into the dough.

Too high a moisture content of flour is undesirable because of the danger of such flour getting musty. Flour from new crop wheat is sometimes quite high in its moisture content. Such flours and all flours containing excessive moisture should be stored until normal. In prolonged rainy weather, flour sometimes gets damp. In such cases proper allowance must be made for the condition so as to avoid over-hydration of the dough.

The proper storage conditions for flour will be taken up later on.

I. PROTEIN OF FLOUR

Protein is a name given to a certain class of food substances which contain nitrogen and which represent muscle building material. The proteins of flour are very important and can be divided into two classes:

(a) Proteins soluble in water. These soluble proteins represent only a small portion of the total proteins of flour and are important in nourishing the yeast in the dough batch during fermentation.

(b) Proteins insoluble in water or gluten forming proteins.

SKELETON OF A LOAF OF BREAD—PURE GLUTEN

REPRODUCED FROM PHOTOGRAPH

This display is a loaf of pure gluten. The gluten of a loaf besides being the muscle-building protein is also the structure or frame work that holds the loaf together and retains the gas in the dough. It is this elastic material which permits the dough to rise and to expand in the oven.

When water is mixed with flour the gluten is formed as a rather homogeneous mass and it is during the mixing process and raising of the dough that the bands, fibres and sheets of gluten which form the supporting tissue of the loaf are developed.

The gluten proteins are very important from a breadmaking standpoint, and are therefore given special consideration by the miller and baker.

XI. GLUTEN

A. DEFINITION

Gluten is the tough, rubbery, elastic substance which is formed in a dough by the addition of water to wheat flour. Gluten can be separated by washing out the remainder of the dough, with water. Gluten comprises nearly all of the protein contained in wheat.

B. WET AND DRY CRUDE GLUTEN

Strictly speaking, gluten thus separated is crude wet gluten, composed of about 2/3 water, and 1/3 dry gluten substance. If all of the water which is contained in the crude wet gluten is driven off by a drying process, dry gluten is left in the form of a tough, crisp, glassy, glue-like mass which can then be reduced to powdered form.

C. COMPOSITION AND FORMATION OF GLUTEN

We often speak of the gluten content of flour, and in general practice the expression has been standardized and accepted by continued usage. As a matter of fact, however, most authorities tell us that gluten does not exist as such in flour,—but is formed by the combination of the two major gluten components of the flour, namely gliadin and glutenin. Crude gluten washed out of flour also includes within itself a small amount of fat, non-gluten proteins, carbohydrates and mineral matter.

Gliadin is of a sticky nature and imparts the adhesive properties to the gluten while glutenin imparts tenacity and strength. These two, unlike protein substances, in combination with each other form a new substance, the gummy, elastic gluten which includes a certain amount of fat and non-gluten protein as described above.

D. THE IMPORTANCE OF GLUTEN WHEAT—THE ONLY SOURCE OF GLUTEN

The importance of gluten in forming the cellular structure of bread has already been covered under the subject of wheat. Gluten imparts elasticity, extensibility and gas retaining properties to the dough. Without gluten, light, porous wheat bread as we now know it, would be impossible.

E. THE TWO FEATURES OF GLUTEN INDICATING ITS VALUE

1. Quality of the Gluten

This means the ability of the gluten to absorb and retain water, to retain the carbon dioxide gas which raises the dough and to stretch readily during the panary fermentation of the dough so as to produce

well piled loaves of good quality. The quality of gluten plays a very important part during the pan proofing stage of the dough and during the first few minutes in the oven. Some indication of gluten quality is secured by examination of the crude gluten which is obtained by washing it out of the flour with water. Inspection of the finished loaf however, gives real evidence of the gluten quality of the flour employed.

It has been contended by many people that gluten quality depends on the exact ratio of the gliadin and glutenin present in any flour. However, later research has indicated that the quality of gluten is governed primarily by the nature of the glutenin present inasmuch as it is known that in different flours the physical properties of the glutenin vary considerably, while the gliadin is usually of the same character in all wheat flours.

2. Amount of Gluten

The quantity as well as the quality of gluten is important from the bakers’ point of view in flour. As a rule, hard spring flour is slightly higher in gluten components than corresponding grades of winter wheat flour. An average wheat patent flour contains about 10.8 to 12.5% of dry gluten components. Shorter separation flour contains a slightly smaller amount of gluten but of better quality than longer separation flour milled from the same wheat.

F. THE SEPARATION OF GLUTEN—ESTIMATION OF QUALITY AND QUANTITY

The gluten can be approximately determined as follows: Scale accurately 25 grams of flour, and in a suitable porcelain dish, mix with 13 to 15 cc.* of water of about 70 degrees Fahrenheit. Note—Water should be of 70 degrees F. during this entire process; otherwise, excessive loss in Protein will result. Mix until the dough is clear, then cover the little ball of dough with water of the same temperature, and allow to stand for one hour exactly.

* (cc. stands for cubic centimeter, 1 cc. of water weighs 1 gram.)

Next, over a fine hair sieve, wash out the starch and soluble matter, using a large excess of water, by kneading the little dough ball carefully between the fingers, taking care not to separate the dough. When the washings no longer become milky, and no visible particles of dough are left in the remaining gluten, it may then be considered washed clean. Care must be taken that no particles of dough or gluten remain in the sieve over which the dough was washed. Allow this fresh gluten to lie in water of same temperature for half an hour; next take from water and press out the surplus water by working the gluten gently between the fingers, and drying the hands occasionally on a towel. Continue this operation until all surplus water has been worked off. Next bring this gluten, which is now in its wet stage, on to a piece of counter-poised paper, and weigh it carefully. The percentage of dry gluten can be readily calculated by multiplying the weight of the wet gluten obtained from the 25 gram sample of flour by 4, and dividing the product by 3, which will give approximately correct results.  The wet gluten may be dried at a temperature ranging from 210 degrees to 220 degrees F., until the weight is constant; and figures thus obtained will agree very closely with those of the calculated dry gluten.

The general condition of a gluten, its color, tenacity, elasticity, stickiness and other points, must be carefully noted before the gluten is dried; and the quality of the gluten then judged by general results.

G. CARBOHYDRATES

“Carbohydrates” is the name given to a class of organic compounds made up of carbon, hydrogen and oxygen which represent energy-giving foods. Starches and sugars belong to this class of compounds, starch being the principal carbohydrate of flour, and constituting the major portion of the endosperm of the wheat. In the baking of bread, the starch is gelatinized in the form of a starch-gluten combination and the dough is thus “set” in the form of bread.

Starch represents about 70% of the average bread flour.

While natural sugar in the form of maltose of sucrose is present in flour in very small amounts, it plays an important part in the panary fermentation of the dough.

Other carbohydrates in the form of soluble starch, cellulose and dextrin may be present in very small amounts.

XII. FAT CONTENT OF FLOUR

Due to the extremely low percentage of fat in wheat flour, this factor warrants little consideration. The normal fat content of patent flour is rarely over 1.5%. An unusually high relative amount of fat in flour would tend to favor the development of rancidity of the flour on storage, and the modern miller therefore, is careful to keep the fat content of the flour down to a minimum. The clear grades of flour contain more fat than the shorter separation patent grades.

XIII. ASH OR MINERAL MATTER IN FLOUR

If a sample of wheat or wheat flour in a chemical laboratory is thoroughly and completely burned up in a porcelain or silica dish, a greyish powder residue remains. This is called “ash” and represents the mineral matter contained in the original sample. This mineral matter in wheat flour consists mainly of the phosphates of lime, magnesium and potassium. These mineral salts are secured by the wheat from the soil in which it is grown, and are located mainly in the bran and germ of the wheat berry. The ash content of wheats vary, soft wheats being a little lower in ash than harder wheats. However, the longer extraction or lower grades of flour from any wheat naturally contain more mineral matter than the shorter separation or higher grades. Thus a clear grade of flour contains a higher ash or mineral content than a straight grade which in turn is higher in ash than a patent grade milled from the same wheat.

The reason why the ash content is higher in the “Straights” and “Clears” than in the “Patents” is due to the more complete removal of the branny substances from the patent flours. The fact that ash content indicates the degree of refinement of a flour is merely because the amount of ash is correlated with the grade as described above. This, of course, does not mean at all that the higher ash content itself is in any way detrimental to the baking properties of the flour.

Ash content of flour therefore, is an indication of its grade but should be considered as such, only when the other quality factors of the flour are also taken into consideration at the same time. The average ash content of bread wheat is about 1.8%, while that of clear grade flour from about 0.7 to 1.0% and the ash of an average patent grade flour varies from about 0.37% to 0.46%. These figures, however, are only approximations.

XIV. ESSENTIAL CHARACTERISTICS OR PROPERTIES OF FLOUR

A. STRENGTH AND STABILITY

The strength of flour may be defined as its ability to produce a high yield of large well piled loaves. Stability of a flour means its ability to produce a dough which does not slacken unduly during fermentation and which is not noticeably sensitive to minor changes in the fermentation period. Stability of a flour is usually tied up with its strength.

The quality and quantity of gluten, the power to absorb and retain water in the dough batch, and the stability of a flour throughout panary fermentation, determines to a large extent its strength or general well-balanced baking qualities. Thus, flours of an unduly strong gluten content favor the production of high yields and the possibility of large loaf volume, but often with coarse grain and harsh texture. Such flours properly blended with a flour possessing a softer gluten result in a flour of optimum baking strength which produces bread of superior eating qualities.

B. ABSORPTION AND RETENTION OF WATER

The term absorption means the amount of water required by a unit weight of flour in order to produce a dough of normal consistency, ideal for bread making; in other words, a dough which is medium soft, and one which can be handled without evidence of stickiness or undue stiffness.

Percentage absorption means the number of pounds of water which can be absorbed, in the manner stated above, by 100 lbs. of flour. The retention factor of flour means the ability of the flour to retain the water previously absorbed by the flour without slackening or developing stickiness during the fermentation period. A dough which slackens noticeably during fermentation is said to lack stability. This is usually due to a poor quality gluten or to the presence of an undue amount of liquefying or proteolytic enzymes which degrade the gluten. Such doughs have to be set stiffer than normally at the start; this of course results in lowering the normal absorption of such flour. In many instances, an increased amount of salt in the dough helps to correct such a condition. The absorp-

tion and retention of moisture is a very important characteristic of any flour, inasmuch as it controls to a large extent, the yield of bread secured. Absorption and moisture retention of any flour depends largely on the wheat from which it was milled, the primary natural moisture content of the flour, its general physical condition, as well as the quality and quantity of gluten components which it possesses. The drier the flour the greater the absorption, provided it is in good condition.

XV. MEASUREMENT OF THE ABSORPTION POWER OF FLOUR

The absorbing power of a flour is determined by weighing out 25 grams of flour into a suitable dish and adding water from a graduated burette; then mixing the two into a dough of the proper standard consistency, which always must be alike for all samples tested. The number of cubic centimeters (cc.) of water used as indicated by the burette, are multiplied by 4, and the product expresses the percentage of absorption.

The result is next confirmed by making a baking test, i. e., using the proper amount of yeast, salt and other ingredients, and taking care to make the dough of the same consistency as before. Weigh the dough carefully and make a record of its weight. Next proceed to work the dough into bread in the usual manner, but very carefully.

Immediately upon drawing from oven, let the bread be weighed, and the loss calculated. This gives a comparative idea of the moisture-retaining power of a flour. In order to get proper results, let the sample dough be carried at a uniform temperature; and the length of fermentation be always the same. The same holds good for the heat of oven, which should be 425 degrees F. Unless uniform conditions prevail, the retaining power of a flour will be affected and comparable results will not be secured.

XVI. THE COLOR OF FLOUR

The color of flour naturally depends on the nature of the wheat from which it is milled, the milling process itself, and the degree of separation represented by the flour in question. Soft wheat usually yields whiter flour than the corresponding grade of flour from hard wheats. Patent flours are whiter in color than the longer separation grades such as “Straight” and “Clears” produced from the same wheat. Color alone is not a definite indication of the baking strength or value of a flour although it is an important factor to be taken into consideration, along with the other quality characteristics of the flour. Good bread flours usually range from a white to a cream color or slightly yellow shade. Usually the color of the flour gives a fair indication of the color of the crumb of the loaf produced from it,—but this is not a hard and fast rule. Final judgment can only be based on an examination of the finished loaf.

Today milling processes are so perfected as to eliminate from the finished flour bran specks, cellulose or other parts of the wheat which would cause undesirable discoloration. The yellowish coloring matter of flour is known as carotin.

XVII. METHOD FOR JUDGING THE COLOR OF FLOUR

The color of various samples of flour can be simply and conveniently compared by means of the well-known “Pekar” test as follows:

1. Place small heaps of flour samples a short distance apart on a glass or smooth wooden board.
2. Press each lot of flour down with a flour slick, which is a small piece of smooth glass or highly polished stainless steel, by bringing the slick from the upper to lower end of the glass or board, so as to leave a smooth surface with no air bubbles.
3. Trim the edges of each heap.
4. Push each lot close to the next lot so that no division or space is left between them. Press down the entire connected strip of flattened flour again with the slick indicating of course, the location of each sample. At this point it is possible to compare roughly the various shades of the samples provided they are thick enough to not be transparent. The samples are next submerged obliquely in a basin of fresh water, quickly withdrawn, set in a slanting position, and allowed to dry in a comparatively warm place. The colors are again noted and differences in shades will be observed by comparison.

With a little practice in this work anyone may easily compare the colors of flours.

XVIII. ACIDITY AND HYDROGEN ION CONCENTRATION OF FLOUR

A. EXPLANATION OF ACIDITY AND ITS MEANING

The name “acid” refers to that class of substances or compounds which are characterized by a sharp sour taste. Acids contain hydrogen in combination with other elements. Acids have the property of turning blue litmus red. An acid and an alkali in contact with each other react so as to neutralize each other and result in the formation of a substance known chemically as a “salt.”

The acidity of any substance may be described briefly as the extent to which it possesses the properties of an acid. A large number of our every day foods possess some acidity. One of the best known indications of acidity is sourness of taste,—but a food may be mildly acid without being noticeably sour to the taste.

B. ACIDITY AND ITS IMPORTANCE IN FLOUR AND DOUGH BATCH

Acidity plays an important part in bread making. A properly regulated acidity in the dough batch stimulates the activity of certain essential enzymes and thus assists in bringing about the normal healthy “ripening” of the gluten during panary fermentation. While sound flour possesses a slight acidity, a still stronger acidity is progressively developed in the dough batch as the panary fermentation,—brought about by the action of yeast,—proceeds.

This acidity must be developed gradually, and not go beyond a certain definite point. An excessive acidity, brought about by the abrupt addition of undue amounts of strong acid to the dough batch would result in the ruination of the gluten. The slight acidity possessed by wheat flour is an important factor in connection with its baking qualities. A certain acidity of flour is very desirable but an abnormal degree of acidity is an indication of unsoundness, and lowered stability. The amount of acidity in flour is expressed in terms of percentage of “lactic acid” for convenience sake, although the actual acidity of flour is due almost entirely to the presence of certain phosphates. These phosphates are termed “acid” phosphates because they possess certain characteristics and properties common to acids,—although strictly speaking they do not come under the usual classification of ordinary acids.

C. HYDROGEN ION CONCENTRATION EXPLAINED

Thus far we have been discussing acidity on the basis of the actual quantity of acidity present. However, in connection with flour and panary fermentation, the importance of acidity is not primarily dependent on its amount or quantity but rather on the actual potential strength or effectiveness of the acidity. This intensity or degree of effective acidity, irrespective of the quantity present, is termed: Hydrogen Ion Concentration. The subject of Hydrogen Ion Concentration in connection with the fermentation and conditioning of bread doughs is explained in Chapter XL The same amount of different acids have different degrees of Hydrogen Ion Concentration. For instance, we have weak acids and strong acids. The acid of vinegar is weak. Ordinary vinegar contains about 5% of acetic acid and is used in liberal quantities on the American table, imparting a delightful flavor to salads, whereas 5% of hydrochloric acid being much stronger, would burn the mouth and is therefore unfit for such use inasmuch as hydrochloric acid has a much greater hydrogen ion concentration than the same amount of ordinary vinegar acid.

In view of the importance of hydrogen ion concentration in connection with the science of bread making, and because of the fact that this factor is mentioned so much in published articles and literature concerning the panary fermentation of doughs, it is essential that the baker of today should understand in a general way, the significance and meaning of these terms. Hydrogen ion concentration or the measure of effective active acidity is expressed by the term “pH.” According to the scientific system of expressing this term,—the higher the “pH” number, the lower the actual active acidity and vice versa. For instance, a dough with a Hydrogen Ion Concentration of pH=5.9 contains less active acidity than a dough of pH=5.1.

D. IMPORTANCE OF HYDROGEN ION CONCENTRATION OF FLOUR

The hydrogen ion concentration of flour up to a certain point influences the baking qualities of flour because of its modifying effect on the dough, either directly or through the activation of certain enzymes.

XIX. THE STORAGE OF FLOUR

The storage of flour has an important bearing on its baking qualities, —particularly the temperature and humidity of the storage room and the length of the storage period.

Flour should not be exposed to an extremely low temperature, but should be kept, if possible, in a cool, dry storage, with an average temperature of 70 degrees F. The storage room should be well ventilated, as flour absorbs and retains bad odors, which are sometimes noticeable in the Bread.

Generally age itself has a tendency to whiten flour, and to improve its bajking value, while freshly milled flour does not always produce the best bread.

During storage flour increases in acidity and improves in color which improves its baking quality up to a certain point when best results are obtained, thereafter it begins to deteriorate. Flour kept too long in storage loses a good deal of its commercial value and must be mixed with fresh flour or results will be unsatisfactory.

Fifteen days in storage is sufficient for all practical purposes and no special reason exists in normal times to store flour for a longer period.

In the course of the modern milling processes the wheat is properly conditioned resulting in a flour which requires no further ageing than is secured during the customary 2 weeks’ storage.

In storing sacks of flour the lowest layer should be placed on skids or planks especially if the floor of the storage room is concrete so as to avoid any undue dampness. The lowest layer of sacks should be laid lengthwise, —the next layer crosswise, etc., so as to permit proper circulation of air. Planks are often used to separate the tiers or layers of sacks, which, however, should not be stacked too high. Keeping the flour storage room relatively cool aids in preventing the development of flour beetles or other insects. Flour sacks should be removed from the storage room as soon as they are empty because of the tendency for flour beetles to develop in them. Such sacks should be cleaned as soon as possible. Many bakeries have installed sack cleaning machines for this purpose. The refuse flour thus secured may be sold to paste makers or to foundries.

XX. BAKING TEST

The composition and essential characteristics of flour, previously described are of material assistance in judging its value from a baking standpoint. However, “the proof of any pudding is in the eating” and the most valuable test of any flour is an actual baking test.

A standard small sized baking test will indicate in a general way,— the baking qualities of a given flour although slight differences may be noted when large commercial batches are made up in the machine equipped bakery.

Usually the small scale baking test is used for comparison purposes, —“check” dough also being made up at the same time using the same formula excepting that a standard flour of known quality is employed. The test dough thus shows the difference in absorption, stability, fermen-

tation time and finished loaf produced thru the use of the particular flour being investigated. With this information the baker can make the necessary changes in handling the flour being tested, when made up into larger scale doughs. There have been a great number of different very good baking tests published which are in general use today. The following “Bachman” test may be utilized to good advantage by the baker:—

Laboratory Baking Test Bachman—

Formula :—

Dough Temperature 80 degrees.

 Explanation :—

Dissolve the sugar, Diamalt and salt in about three-quarters of the water which has been properly tempered. The balance of the water is used in dissolving the yeast. Draw the flour into the water which has dissolved the sugar, Diamalt and salt. Now begin mixing. When partly mixed draw in your yeast solution; when the dough is almost smooth add your fat and continue mixing until perfectly smooth. Dough should then be placed into some sort of cabinet which has been previously heated to 83 deg. F. where it is allowed to remain until it recedes to the touch of the hand. It should then be punched down, allowed to lay 20 minutes and then made up into bread in the usual way. After bread is baked it should be allowed to cool; then cut to determine color, flavor, grain and texture.

XXI. NEW CROP FLOUR

A. YEARLY VARIATIONS IN FLOUR

As explained previously, the baking properties of any flour depend primarily on the character of the wheat from which it is milled and this in turn is largely dependent on the weather conditions prevailing during the growth of the wheat crop.

It is therefore, obvious that each year there will be unavoidable differences in the character and baking properties of new crop flour. Furthermore, different types of any new crop flour produced in different sections of the country vary in the quantity and quality of gluten, absorption and in general strength and stability.

No one can predict just exactly what these differences in flour characteristics from year to year will be until the flour in question is milled

NOTE—Much valuable information regarding experimental baking tests can be secured from various issues of “Cereal Chemistry” which is the publication of the American Association of Cereal Chemists.

and tested. If possible, it is advisable to blend some old crop flour with the new crop flour when first received.

B. REPORTS ON BAKING TESTS ARE ISSUED CONCERNING NEW CROP FLOUR EACH YEAR

Every year the problem of handling new crop flour confronts the baker. However, the solution of this problem is being made easier through the diligent work on the part of the milling concerns, various institutes of baking, and laboratories which conduct careful tests on the baking qualities of the new crop flour prior to its shipment to bakers.

The results of these tests, a description of the differences observed in new crop flour from various sections and definite instructions regarding the proper handling of the flour so as to secure the best results in baking are distributed to the bakers by word of mouth, letters, bulletins and published articles in the various trade journals.

Therefore, with the advent of new crop flour each year, it behooves every baker to secure necessary instruction concerning the peculiarities of the new flour and definite suggestions on the handling of the same in his doughs.

A preliminary small scale baking test conducted by the baker will also shed much light on the baking qualities of the flour and the necessary changes to be made in absorption, amount of salt, length of fermentation period, and so forth.