& COMPARISON OF SPRING AND WINTER Msi NM RO Me oes wee ee Fh te DA eo 8 ENE Thesis for the Degree of M. §. Bessie Belle Hoover 1915 cD Qt Oo A COMPARISON OF SPRING AND WINTER WIBAT FLOUR AS INFLUENCED BY COMPRESSED, DRY AND LIQUID YEASTS. THESIS FOR DEGREE OF M.S. Bessie Belle Hooyer 1915 THESIS INTRODUCTION. . The purpose of this work has been to determine by baking tests, the difference in the bread making qualities of spring and winter wheat flour, and, if possible, to work out a method by which bread fran the latter could be made to equal the former in quality. It has been said that good bread cannot be made from winter wheat flour. The extent to which this crop is grown in the United States, shows the importance of proving the contrary. The Agricultural Outlook for May, 1914, Farmers’ Bulletin 598, reports the year's yield of winter wheat in the United States to be 630 million bushels and estimates that of spring wheat at 250 million (the average yield for five years), making a total of 880 million buehele, of which nearly three-fourths is winter wheat. The following Statistics of state yield from the same bulletin show the wide range of territory over which it is grown. LOL 1: Table f. WINTER WHLAT. ~~ srAt> ACREAGE BUSHELS. Forecast from May 1 conditions New York 360,000 7 500 New Jersey 79,900 1,400 Pennsylvania 1,312,000 23,400 Delaware 114,000 1,900 Maryland 612,000 9,900 Virginia 779,900 10,000 West Virginia 236,000 3,200 North Carolina 611,000 6,500 South Carolina 80,900 900 Georgia 140,000 1,600 Qhio 2,990,900 38,900 Indiana 2,485,000 45,500 Illinois 2,576,000 47,500 Michigan 03 » 900 15,0800 Wisconsin 5,000 1,600 Minnesota 41,000 acon Iowa 479,000 11,100 Missouri 2,549,000 44,200 South Dakota 69,900 coun Nebraska 3,123,000 63,000 Kansas 7,950,000 132,000 Kentucky 745,000 102,000 Tennessee 709,000 8,600 Alabama 31,900 400 Mississippi 1,900 eowe Texas 1,082,000 15,600 Oklahoma 2,465,000 35,500 Arkansas 105,000 1,300 Montana 481,000 12,900 Wyoming 41,000 1,100 Colorado 194,000 4,800 New Mexico 42,9000 900 Arizona 31,000 900 Utah 2032000 5,500 Nevada 15,000 400 Idaho 339,000 10,100 Washington 1,201,000 33,900 Ore gon 633,000 15,200 California 408,000 7,800 United States 35,307,000 630,000 In August, 1896, this College sent out a circular* to about two hundred farmers of the state, asking what varieties of wheat were grown in their locality and which were grown most extensively. Seventy-five varieties were reported and of these but three were of spring wheat and these were grown only in limited sections north of Saginaw Bay where winter varieties do not thrive. The Iowa Agricultural College Experiment Station, Bulletin 51, on Winter Wheat, gives a comparison of the acreage of spring and winter wheat grown in that state, showing the increase in the latter. In 1885, one twentieth of the crop was winter wheat while in 1898, it had increased to one sixth. The yield per acre with but few exceptions was larger from winter than from spring wheat. At the Experiment Station, the yield fran winter wheat was almost double that of spring. The following quotation from this bulletin shows the value and advantage of growing this crop. “The Station wishes to encourage farmers to grow a larger acreage of winter wheat. The spring wheat belt is creeping northward, leaving in its trail lands admirably adapted to the growth of this crop. It furnishes one of the vest nurse crops with which to establish grasses and clover, for the reason that it draws lightly upon the supply of soil moisture as compared with other cereals, and is ready to harvest before Warm weather sets in, the season most liable to injure *“Wichigan Agricultural College Experiment Station, Bulletin 141, February, 1897. . =2e young clover. By giving it place in the rotation, labor is distributed more evenly throughout the year, seed time caning as it does when work is slack in the fall, end harvest immediately efter haying. Besides, it is one of the most profitable crops on the farm, the Station wheat being worth upwards of thirty dollars per acre this season", Since winter wheat is grown so successfully and so extensively in the United States, the importance of developing a variety that will withstand the cold winters, yield a large crop and at the same time possess good milling and baking qualities hes long been recognized. The Agricultural Experiment Stations have been working along this line for many years. The problem of the farmer is, therefore, to raise a good winter wheat, of the miller, to produce a good flour and of the housewife, to understand how to use it successfully in order that it may hold its place on the market with spring wheat as a bread making flour. Differences between Spring and Winter Wheat. Since spring wheet is considered essentially a bread making flour, it is of interest to note what qualities are necessary for this, and wherein it differs from winter wheat. Spring wheat is grown in the Northwest, principally in Minnesota, the Dakotas, and Canada where the winters are too severe for winter wheat. It is planted in the spring and harvested the same year. Winter wheat is grown in various sections of the United States, as the above tabulation shows. It is planted in the fall and harvested in the early =3- summer of the following year. The kernels of winter wheat, especially the soft varieties, are large, plump, and starchy, while those of spring wheat are emall, hard end glutinous. Winter wheet flour is white and powdery with a tendency to cake when gently shaken in a sieve. It feele velvety and retains the imprint of the fingers when pressed in the hand. Spring wheat flour ie creamy in color, feels granular, readily passes through the sieve and does not retain the imprint of the fingers when pressed. A given weight of spring wheat flour will absorb more water than an @qual weight of winter wheat flour. A given volume of spring vheat flour wéighs more than an equal volume of winter wheat flour, Chemical Composition. The chief difference in the chenical composition of spring and winter wheat is in the starch and gluten content. Since winter whest must live through the winter, it is necessary to store up nourishment, hence it usually contains e® larger proportion of starch. Spring wheat grows and matures more quickly, does not require so much nourishment,and is usually richer in gluten. However, there is a wide range of variation in the composition of the different varieties of both spring and winter wheat as Table 2 shows. This is influenced largely by soil, climate and rainfall, Table 2.* COMPOSITION OF WHEAT. — ~ ~ Carbo-= ~ Water Protein Fat hydrates Ash ~~~ ___J % % Snuring Wheat 10.41 15.50 2.28 69.88 +693 Straight Patent Flour 12.38 13.60 1.30 72.04 06 Winter Wheat 10.25 1234 1.35 74.23 1.83 Straight Patent Flour 10.97 10.92 50 77.15 ° b,.** Spring Wheat | Patent Flour 7.68 12.42 1.16 78.08 63 Winter Wheat 7274 10. 53 98 80.30 045 c,*e% Spring Wheat 10.4 12.5 2.2 73. 1.9 Winter Wheat 10.5 11.8 2.1 73.8 1.8 * U.S. Dept. of Agriculture, Office of Experiment Stations, Bulletin 126, Pe 13. ** North Dakota Agriculture College, Experiment Station, Bulletin 82, p. 763,764. ***Farmers' Bulletin 389, p. 16. whe Gluten is the substance in flour that retains the carbon dioxide formed during the fermentation of the dough, thus making possible a light spongy loaf. It forms thin elastic walls about the gas bubbles, and as these are expanded by the heat of the owen, the walls become distended and ere coagulated. It is formed when flour is mixed with water, by the combination of two proteins, gliadin and glutenin. Gliadin is an elastic glue-like substance, sometimes called a plant gelatin, which binds the flour particles together and gives tenacity and elasticity to the dough. It may be extracted from gluten or flour with dilute alcohol. Glutenin is the substance to which the gliadin adheres. It prevents the dough from becoming too soft and sticky. It is soluble in dilute alkali. Gliadin and glutenin together constitute about . nine-tenths of the protein of the wheat kernel. Osborne and Vorhees*, who have made an extensive study of the subject, have found three other proteins in wheat, namely: i. Edestin, a globulin belonging to vegetable vitellins, soluble in saline solutions. This constitutes from .6 to .7 percent of the wheat kernel, 2. Leucosin, an albumin which coagulates at 52 degrees and is unlike animal albumin in being precipitated on saturating its solutions with sodium chloride or magnesium sulphate. * Jour. of American Chemical Society, 16, pages §24-535, Su 3. A proteose, precipitated (after globulin and albumin have been removed) by saturating the solution with sodium chloride or by adding 20% of sodium chloride and acidifying with acetic acid. Qualities of a Bread Flour. Among the essential qualities of a good bread making flour are strength, color and flavor. Strength of Flour. Spring wheat is usually spoken of as a strong flour, winter wheat a soft or weak flour. Authorities agree in ‘conisdering strength an important factor in a bread-making flour, but just what constitutes strength has been a matter of wide discussion. It has been defined as the “water absorbing power" of a flour. Since the ability to absorb water depends upon the gluten present, a high gluten content is often associated with strength, Some investigators say it is not the amount but the quality of the gluten that is important. Snyder* maintains it is the ratio of gliadin to glutenin, which should be in the proportion of 63 : 35. Other investigators have found that flour may have the right proportion of gliadin to gluten and yet be lacking in baking qualities. —— peat nl * Minnesota Experiment Station Bulletin 63. -6< T. B. Wood* adopts Humphries and Bissen's definition of strength: "The capacity to yield a large well piled loaf*® and maintains that two factors are involved in it, size and shape which he finds are due to different causes. Size, he says, depends upon the capacity of the flour to give off gas during fermentation. The amount of gas evolved depends upon the quantity of sugar contained in the flour together with that formed in the flour by diastatic action. Shape, he finds, and possibly gas retention, depend upon the physical properties of the gluten as modified by the presence of varying proportions of salts. Color, Good bread flours - those with a large proportion of gluten - are not white but are of a creamy color. Since there was a demand for a flour that would yield a white loaf of bread, the practice of bleaching flour became common. According to Leach**, in 1908, about eight percent of the flour produced in the United States was bleached by nitrogen perodide, but as aresult of the enforcement of federal law, the practice has been largely abandoned. Whiteness in flour may be due to a low gluten content, age or bleaching. A grayish color indicates a poor grade of flour. * Jour. Agr. Sci. 2, 1907, pp. 131 ~ 160. ** Teach, Food Inspection and Analysis, p. 315. Flavor. A good flour should produce a bread with a sweet nutty flavor. Winter wheat is said to yield a better flavored flour than spring wheat and is often blended with it because of its tenderness and flavor. Nutritive Value of Bread from Spring and Winter Wheat Flour. The question sometimes arises as to the conparative nutritive value of bread from spring and winter wheat flour. Harry Snyder of the Minnesota Agricultural Experiment Station has made experiments with three different grades of flours - graham, entire wheat, and patent - from both spring and winter wheat .* He finds the patent flour of both varieties of wheat to be more thoroughly digested and to yield a larger proportion of nutrients than the graham and entire wheat flours, though the latter are richer in mineral salts and protein. The coarser particles of the latter two are not so readily acted upon by the digestive juices, so more is lost in digestion. The results of his experiments show the digestibility and avail- ability of energy to be a little higner for winter than for spring wneat. Since the calorific value of spring wheat averages a little higher than that of winter wheat, the nutritive value of each would probably be about the same. The calories per “8, Dept. of Agr., Office of Experiment Stations, Bulletin 126. gram are given as follows: Spring Wheat, Straight Patent Flour 3.861; Winter Wheat, Straight Patent Flour 3.799%. Digestibility of Nutrients and Availability of Energy of Bread. Hard Spring Wheat. (Page 29) Kind of Food Protein Carboe- Energy hydrates White Bread (Standard patent ) Average of 3 88.3 97-7 90.9 Average of 3 (1899-1900) 85.3 97.5 90.1 Average of 6 86.8 97.6 90.5 Soft Winter Wheat. (Page 45). White Bread (Standard patent) Michigan Wheat Average of 3 92.8 98 94.2 Indiana Wheat Average of 3 88.9 96 90.4 * Page 13. =I- Yeast. Yeast is a microscopic unicellular plant belonging to the fungi family which includes those plants that contain no chlorophyll and that reproduce by buds and spores. Yeasts are classed as true yeasts, Saccharanyces, including wild and cultivated, and pseudo yeasts, or false yeasts, Torula and Mycoderma ,.* True yeasts produce fermentation and usually are able to form endospores. During fermentation some of the yeasts tend to sink to the bottom while others rise to the top and form a thick foamy layer on the surface. The former are called bottom yeasts, the latter, top yeasts. The cultivated varieties used in brewing and some of those in producing distilling material are grouped together as Saccharanyces cerevisiae. They are divided into three groups: the bottom yeasts, used in making German beer which produce only a amall amount of alcohol; the top yeasts, used in English beers, which produce more alcohol; and the distillery yeasts which have great fermentive power and produce large amounts of alcohol.**® Among the wild yeasts are Saccharomyces minor, the yeast of leaven and Saccharomyces ellipsoideus and Saccharomyces apiculatus, the wine yeasts. Wild yeasts are abundant in the air and produce spontaneous fermentation in various substances. The leaven of the ancients was obtained * M.A.C. Bacteriology Syllabus, page 70. ** vMershall, Microbiology, page 31. ~-10- by allowing cough to ferment spontaneously. The wine yeasts are found on grapes. These are cultivated and pure cultures are often used in wine making. Pseudo yeasts do not form endospores and produce little or no fermentation, though they often occur in fermenting liquors. Those known as Torula are not considered hermful, but those classed as Mycoderma, which grow upon the surface of the liquid, producing there a thick film, cause wine to become insipid and cloudy, and finally spoil it completely. Structure and Reproduction of the True Yeast, Saccharonyces. The cells of this yeast are large, round or slightly oval. The vigorous young cells, when seen under the microscope, appear nearly transparent. A thin well-defined cell wall encloses the cell contents, or protoplasm, which is slightly granular with one or more small cavities, called vacuoles, which are filled with cell sap and contain small granular bodies, These bodies are probsbly waste products. As the cell grows older, the wall thickens, the protoplasm becomes less transparent, the size of the vacuoles increases and the granular bodies become more numerous. Dead cells are usually opaque and take the stain more readily than living cells. ell. Budding. When the cell has reached a certain size and is kept under suitable conditions, a protuberance or bud is sent out from part of its surface which gradually increases in size and becomes separated from the old cell by a cell wall. The new cell or daughter cell may or may not remain attached to the mother cell. If it does so, and the old cell continues to form buds, a mass of cells is produced. If each new cell formed produces a bud, a chain of cells will be formed. The old cell may produce a number of buds, but in time its reproductive energy is exnausted and tne cell breaks up.* Formation of Spores, “When young, vigorous, well-nourished cells are supplied with abundant air and moisture at a comparatively high temperature under conditions that discourage budding (lack of nutriment ), they form endospores. These spores are usually about half the diameter of the mother cell and from one to eight or more may occur in each cell" ,** The spores ere very resistant and will remain dormant a long time, but when placed in a nutrient solution will swell and burst the mother cell, forming new cells which reproduce by budding. *Ontario Agricultural College and Experiment Farm, Bulletin 118. “Yeast and Its Household Use", William Jago and William C. Jago, “The Technology of Bread Making" ,pege 155. ** Marshall, Microbiology, page 30. ms Conditions Necessary for Growth of Yeast? In order that the yeast cells grow and induce fermentation, certain conditions are necessary, namely: proper temperature, food and maisture. Temperature - The optimum temperature for growth is from 25. to 35 C or 77° to 95° F. Below 25° C growth proceeds slowly, at 9° C (49.6° F) growth ceases, tut will begin again under favorable temperature. Freezing does not i) the cell unless it be mechanically ruptured or injured. Temperatures above 35° C weaken the action of yeast. At 60°C, the coagulating temperature of albumen, the cells of moist yeast are destroyed. Dried cells may be heated to 100° C without destroying their vitelity. Food = Yeast requires for its growth sugar, nitrogenous compounds, and mineral salts. Of these, sugar is by far the most important. Glucose is the only sugar that is directly fermented by yeast. Cane sugar must be changed to glucose before it can be assimilated. This is effected by the enzyme, invertase, which is secreted by the yeast cell. Yeast is said to contain another enzyme, maltose which is capable of changing maltose to glucose,** w Jago, 150 -165 **Jago, 138. el3jeo Experimental work has shownthat the action of yeast on the proteins of wheat and barley flour will enable them to produce diastatic action on starch - that is, change it to dextrin and maltose - after which it is fermented by the yeast.* sufficient nitrogen is usually present in the growing medium; must, wort, potato water, etc. Hard water usually contains the necessary mineral salts. Moisture = A certain amount of water is necessary for the growth and development of yeast. Solutions containing over thirty- five percent of sugar will not ferment. The housewife makes use of this fact in making jellies and preserves, Action of Yeast.** When yeast is placed in a nutrient solution, it feeds upon the sugar present and excretes alcohol and carbon dioxide. The former remains in the solution, while the latter rises to the surface in small bubbles carrying some of the yeast cells with it which form a foam or scum. This phenomenon is known as fermentation, the word being derived from the Latin, ferveo, I boil, and is so called because of the boiling or seething appearance of the liquid. ee ® Jago, 138. **Jago, 145 - 150, 14. It is only within the last century that the true nature of fermentation has been understood. Previous to this time, various views were held. One of these regarded fermenta- tion as a peculiar condition assumed by nitrogenous matter during the process of decanposition. Another held that it was due to a vegeto-animal substance, called a ferment, which was found in grapes and grain, and which, when the grapes were crushed and the grain moistened, produced an astive change. Scientific researches with the microscope aroused further discussion. As early as 1680, Antonius van Leeuwenhoek, a Dutch naturalist and a maker of lenses, discovered that yeast consisted of minute granules. Nothing further was learned of its structure until 1836 when de Latour discovered that it consisted of a mass of little cells capable of reproduction by budding. “Yeast”, he said, “must be an organiam which, probably by some effect of its growth, effects decomposition of sugar into alcohol and carbon dioxide, * After much discussion yeast was finally placed among the fungi and a new order, Saccharomyces, created for it. De Ialtour's view, however, found many opponents. Prominent emong them was Liebig, the celebrated German chemist, wno maintained that yeast was a lifeless substance and fermenta- tion a purely chemical action unassociated with any vital process. For a number of yeare, there were three contending theories of fementat ion: de Latour's, or the vital hypothesis; Liebig's, or the mechanical hypothesis;and other views based on catalytic action, 215 In 1857, efter careful and exhaustive research work on the subject, Pasteur concluded that fermentation is a “correlative phenamenon of a vital act beginning and ending with it® and that there is “never any alcoholic fermentation without there being at the same time, organization, development, and multiplication of globules, or the continued consecutive life of globules already formed," In 1870, Liebig admitted that yeast was an organism but still maintained fermentation was a mechanical act similar to enzymic action, basing his opinion on the fact that the enount of sugar decomposed was out of all proportion to the enount assimilated, This led to further discussions and researches, which resulted in the discovery of zymase by Buchner in 1897. This is an enzyme secreted within the cell, but which may be extracted from it and convert glucose into alcohol and C Oo independently of the living organism. It has no reproductive power and only a fractional part of the fermentive power of yeast. It is destroyed during fermentation almost as soon as formed, so there is no accumulation of zymase in yeast. According to the zymase theory of fermentation, sugar enters the interior of the living cell by diffusion and is there acted upon by the enzyme, invertase, which changes it to glucose: glucose is then converted into alcohol and carbon dioxide vy the ection of zymase. No clear explanation has been offered for the fact that the matter consumed during fermentation is so much greater than the consuming agent. It is Buggested, however -16- thet it may be because the yeast not only derives nut riment from the sugar, but also the heat necessary for the continuance of life. Hence, during fermentation, in order to obtain heat and nourishment, yeast attacks sugar and excretes carbon dioxide and alcohol as waste products. Varieties of Yeast Used in Bread Making. The yeasts used in bread making are compressed, dry and liquid or brewer's yeast. Compressed yeast® is the product of distilleries where malt and raw grain are fermented for spirits. Most of it is made from whiskey wort, some from the worts used in the manufacture of gin and other distilled liquors. The top yeast, which is the most desirable for bread making, is skimmed off, washed in cold water, and strained through silk or wire sieves to remove impurities. It is then pressed in bags in hydraulic presses, after which it is cut into cakes, wrapped in tinfoil and kept in cold storage until distributed for use. Potato, corn or tapioca starch is often added to compressed yeast, on the ground that it acts as a drier, increases the keeping qualities, and produces a cleaner product and one that is more readily mixed with the other ingredients of the bread. The quantity added varies from 5 to 50 percent, the larger amounts being added to make weight. * Food Inspection and Analysis, Leach. page 328. -l7e T. J. Bryan* maintains that the carbon dioxide value of yeast is reduced by addition of starch, and that the percentage of reduction is greater than the percentage of starch present, wnile the keeping qualities are less than those of pure yeast. U. 8. Rulings. Food Inspection Decision, No. lll, Jan.7, 1910. 1. The term compressed yeast without qualification means distiller's yeast without admixture of starch. 2. If starch and distillers yeast be mixed and compressed, such a product is misbranded if labeled or sold simply under the name "Compressed Yeast". Such a mixture or compound should be labeled "Compressed Yeast and Starch", 3. It is unlawful to sell decanposed yeast under any label ° Compressed yeast does not keep well, so it should be used fresh, When fresh, it should have a uniform creamy white color, a pleasant odor and should break with a sharp grain. Dark color and a cheesy odor indicate decomposition. When it becomes soft, it is unfit for use. Dry Yeast = Dry Yeast is s mixture of fresh yeast and starch or cornmeal. It is molded into a stiff dough and dried either in the sun or at a moderate temperature under reduced pressure. When dry it is cut into cakes and put into packages. Since drying renders the cells torpid and temporarily inert, it acte more slowly than compressed or brewer's yeast, hence can not be *Bulletin 116,p. 25. Bureau of Cehmistry. U.S.Dept. of Agr. -18~ used for short process bread. This yeast will keep a year or longer, hence is convenient where compressed yeast can not be obtained. Brewery or Liquid Yeast. Brewer's yeast is obtained from the fermenting vats of the breweries, the top fermentation being preferable. The first yeast that rises contains impurities, so should be rejected as should also that formed during the last period of fermentation since the yeast cells have been weakened by growing in an exhausted medium. The best yeast is produced wnile fermentation is most active and vigorous. Liquid yeast is often made in the home, various recipes being used which consist of mixtures of potato, flour, potato water or water with a little yeast for a starter. This should be kept in a cool place to prevent the growth of bacteria which develop when the yeast cells are not active. Since the food supply becomes exhausted during fermentation, a little sugar added from time to time will keep the yeast more vigorous. Better results will be obtained from this yeast if it be made frequently. Experimental Work. The experimental work was done in the Domestic Science Laboratory. An automatic electric sponge oven which maintained an even temperature of 35 C was used for raising the dough and a Hughes electric oven for baking purposes. The dough was mixed with a spatula in the upper part of a double boiler, the water in the lower part being kept at 42 C. The liquid used was heated to 37 C, this being sufficient to keep the temperature of the dough at 35 C without warming the other ingredients. The pans used for baking were 6-1/4 x 4-1/4 x -2@5/8 inches. This size was a little small for the amount of dough used but was valuable in showing the strength of the flour. Since the sides were not high enough to support the dough when risen to its full height, in unfavorable conditions, that from weak flour ran over the sides. The following recipe was used, subject to variation in different series of experiments. 340 grams flour - 2=3/4 to 3-1/8 oups sifted flour according to variety. 10 grams lard - 2 tsp. 6 grams salt -1 tsp. 14 grams sugar - 2-1/2 tsp. 10 grams yeast ~ 3/4 cake compressed. 170 = 205 cc. water according to the flour used. About 200 cc. was used for spring wheat, from 170 to 190 for winter wheat. lL coup water = 225 cc. -20= The dough was weighed as soon as it was mixed. The hot loaf was weigned in the pan when taken from the oven. The moisture loss is so great at first that unlese the weight of the loaf be determined at a definite time after each baking, grave errors result. The loss in fermentation and baking was computed in grams and in percent. To obtain the volume, the loaf was placed in a bell jar of 3375 cc. capacity and surrounded with flax seed which was léveled with the spatula and then run out through a rubber tube in the bottom of the jar into a graduated cylinder of 2000 cc capacity. The amount of flax seed displaced was measured and the volume of the loaf obtained by difference. The ratio of weight to volume was canputed. The first series of experiments was performed before the electric equipment was purchased. Because of the difficulty in keeping conditions constant, accurate data could not be obtained, so results are given in a general way only. The series was repeated later under more favorable conditions. The amount of yeast was varied, the other ingredients remaining constant. The same recipe was used for both spring and winter wheat flour, one used the previaus year in Problem Cookery. This called for 340 grams of flour and 225 cc. of water, the other ingredients in the proportion cited above. This amount of water made the dough from winter wheat flour so soft that it was necessary to add considerable more flour while kneading. A certain amount was ~2le» weighed and the quantity used determined by weighing what was left. When an equal amount was used with spring wheat, the dough became too stiff. An unavoidable loss resulted from the dough's sticking to the kneading board. The general result for both spring and winter wheat wes an increase in volume and a decrease in the time of rising with the increase in the quantity of yeast used. It was evident that a different method must be adopted if satisfactory and accurate results were to be attained. Varying the Amount of Water. In order to determine the amount of liquid necessary to make a dough of desired stiffness for both spring and winter wheat flour, a series of experiments was performed in which the amount of water was varied, the other conditions remaining cnnstant. The same amount of water was used with both spring and winter wheat flour. This time the method used in Problem Cookery was followed. The dough was not kneaded. After doubling its bulk, it was cut down to allow the gas to escape, then given two risings of one half hour each, after which it was cut down for the third time and placed in baking tins. When it had doubled its bulk, it was baked forty minutes in the electric oven at 180° to 200°C. The temperature was allowed to rise gradually from 180 to 200. then to fall gradually to 190° or 180°. After several experiments with different temperatures, this was found to be best for the oven used. In the gas oven, it was possible ~22u to use a higher tenperature for part of the baking, but since the electric oven heats and cools slowly, it was found best to maintain a more nearly uniform temperature. The texture of the breed was not so fine as when kneaded, but very little of the dough was lost since it was possible to obtain almost all of it with a spatula. In some cases, less than five tenths of a gram was left. In fact, the amount was so small it was disregarded in comput ing results. Pillsbury's Best, a Minnesota spring wheat flour and Thoman's Moss Rose, 2a Michigan winter wheat flour were used for this and the previous series of experiments. 225 co. of water was used for the first loaves, the emount being decreased 10 occ. with each succeeding baking until 195 cc. was reached. It was then decreased 5 cc. to 180 cc., this amount of liquid being about the minimum for the spring wneat flour. With 225 cc. of water, the texture for both spring and winter wheat was coarse, due, in part, to lack of kneading, in part, to the soft dough. The loaf fram winter wheat flour cracked and ran over the side of the pan as shown in photograph 1, while the one from spring wheat held its shape. With 215 cc. of water, the loaf from winter wheat again ran over the sides of the pan. Part of it was lost in the oven, so the correct weight and volume could not be obtained. This accounts for the fall in the curve on the chart. ~ 23 The loaf from spring wheat was lighter, of larger volume and the distribution of gas was more even than that of the first one baked. 205 cc. of water gave better texture and an increase in volume for both spring and winter wheat. 190 cc. gave the best shaped loaf from winter wheat flour. For the first time, there was no crack in the crust. The grain was somewhat coarser than that of the loaf from spring wheat flour, bout otherwise the texture was good. This received the highest score, 90. 185 oc. gave an increase in volume in both cases, and a fairly good shaped loaf from winter wheat but the crack so characteristic of this wariety of flour was again in evidence. 180 oc. produced loaves samewhnat smaller in volume, the decrease in the one from spring wheat being greater thah that in the one fram winter wheat flour. The loaves were of fine close texture, but too dry. Results - {1) With but one or two exceptions, the spring wheat flour yielded a loaf of larger volume and of better texture than the winter wheat flour. Loaf No. 1, spring wheat, was smaller in volume beSause it did not have time to double its bulk in the baking tin. o24~ (2) Until too stiff a dough was reached, the volume in voth cases increased with the decrease in amount of liquid. Loaf No. 2, Winter wheat, is an exception, vecause part of the dough ran out of the pan. (3) The amount of liquid used made very little difference in the time of rising, the slight variation being due to the condition of the yeast rather than to the consistency of the dough. With a larger amount of dough, this mignt not hold true. (4) This variety of winter wheat flour rose more quickly than the spring wheat in the first rising but, in most cases, was a little slower and more irregular in the last. (5) The ratio of weight to volume tended to increase with the decrease in liquid. The ratio for spring wheat was greater than that for winter wheat. (6) The loss in weight during fermentation and baking averaged about the same for the two flours, 11.33 % spring; 11.08 % winter. (7) As the amount of water was decreased, a finer Closer texture was produced, (8) 190 cc. of water for Moss Rose and 205 cc. of water for Pillsbury gave a dough of the desired consistency. The latter was taken as a standard in determining the amount to be used with other flours. A dough made fram 30 grams of Pillsbury's Best would require 18.08 oc. of water or toughly 18 co. In using a new flour, a dough was first made of =25= Pillsbury's flour in this proportion, 30 grame of flour to 18 oc. of water. 30 grams of the new flour was then mixed with enough water to make a dough of the same consistency. The amount of water necessary for 340 grams of flour was determined. Va “Kind — of No. Water Yeast Flour 1 225 10 gms 2 us CU Spring 3 205 . Wheat 4 195 “ Pillsbury's 5 190 « Best 6 185 « 9 180 « 1 225 10 gms 2 215 ° Winter 3 205 « Wheat 4 195 ° Moss Rose 5 190 “ 6 185 " 7 #«»180 « 2is anitted in the ave MECHANICAL ENGINEERING DEPARTMENT M.A. C. @o2/@ Long Process Bread with Varied Amounts of Potato. The U. 8S. Department of Agriculture, Bureau of Chemistry* has been making baking experiments to determine the value of the use of potato meal with wheat flour in bread making, the purpose being to reduce the cost. This is used extensively in Germany and Austria. In the latter country, bakers are now required by law to use at least 30 % of potato meal in making their bread. From 25 to 50 % was used in the experiments at Washington. Loaves made with fran 25 to 30 % of the meal were most satisfactory. Though coarse in texture and of a dark color, the bread is said to have an agreeable and distinctive flavor, and to retain its moisture longer than that made fran ordinary wheat flour. In some of the experiments, the imported “potato flake" was used, in others, a meal prepared in the laboratories of the department. Both of these differ from the ordinary potato meal on the market. The Bureau of Chemistry suggests the use of cooked potato in place of the potato meal, believing that tt: might serve the same purpose if used in the right proportion, In ordér to determine how much cooked potato mignt be successfully used in bread making and to compare its * article for Sunday Papers of Feb. 14, 1915. Office of Information, J. 5. Dept. of Agriculture. =28e effect upon spring and winter wheat flour, some experiments were made in which varied amounts of it were used. A loaf from each variety of flour was baked without any potato, as a standard for comparison. Then fifty grams, (half of a anall potato) was added to each loaf. This made about one fourth of a cup of mashed potato. This amount was increased twenty-five grams with each succeeding baking until one hundred fifty grams was reached. Method - The recipe used in the previous baking tests was followed, in most of its ingredients. 3¢ grams of dry yeast was substituted for the compressed and the amount of water was decreased with the increase in potato. The potato was weighed raw after being pared and washed. Enough for the two loaves was cooked in two cups of water. When they were thoroughly done, the water was strained through a sieve, measured in a graduated cylinder and divided equally. While boiling hot, half of it was poured over the sugar, shortening and + cup: of spring wheat flour, and the other half over the Sugar, shortening and the same amount of winter wheat flour. Bach mixture was stirred witil smooth. The potato was rubbved through a sieve, weighed, and divided equally, half being added to each mixture. When the dough had cooled to 35 C, the yeast, which had been soaking in 30 cc. of luke warm water, was added. =290 This was mixed at noon and allowed to ferment at room temperature until the next morning, when the salt and the rest of the flour was stirred in and enough water added to make a dough of standard stiffness. The amount of water required decreased with the increase in potato, as stated above, but not regularly, since the percentage of water absorbed by the potato while cooking, varied. When the dough had doubled its bulk, it was thoroughly worked with a spatula, Placed in baking tins and baked when it had again doubled in volume. The flour was partially cooked or gelatinized, because in this condition it is more stimulating to the yeast than raw flour, while the dry yeast, being slower in action, requires more stimulation than the compressed or liquid yeasts. The potato and potato water have also a stimulating effect upon the yeast - hence by morning, an active fermentation had set in. Pillsbury's Best and Lily White were the flours used in this series. The latter is a softer winter wheat than Moss Rose. The sponge test showed that 180 cc.of water was the amount required to make a dough of standard stiffness. This amount was used in the loaf baked without the addition of potato. There was such wide variation in = 3Q= volume, time of rising, etc. that the experiments were duplicated and the average recorded. More satisfactory and uniform results were thus obtained. Results e (1) The bread from winter wheat flour was more nearly like that from spring wheat flour in texture and in volume than in the baking tests in which no potato or potato water was used. In one or two cases, loaves of exactiy the same volume were produced. Since average results only are recorded, the table does not show this. (2) Though the winter wheat flour was a softer flour than that used in the previous experiments, it yielded loaves of larger volume, due to the potato or potato water. (3) With both spring and winter wheat flour, the volume of the loaf increased with the increase in potato up to the addition of 125 grams. With 150 grams, there was a decrease in volume. (4) The ratio of weight to volume showed less variation in spring wheat than in winter wheat flour. 1400 grams of potatoes produced the highest ratio in both cases, 2.66 for spring, 2-77 for winter, 150 grams the lowest. . o3le (5) Winter wheat flour required a longer period of fermentation in both the second and third risings than spring wheat. | (6) The addition of potato produced a finer silkier texture in the bread from both spring and winter wheat flour, Bxcellent results were obtained with 100 grams or one-half cup of mashed potato to a loaf. In no case was a soggy loaf produced, yet those from the larger quantity, 125 and 150 grams, lacked lightness and the texture was not so good as when analler amounts, 50 to 100 grams, were used. (7) The addition of potato improved the keeping quality of the bread. -_—— © @ @ ee ,ldUmUC UUme ee MECHANICAL ENGINEERING DEPARTMENT M.A. C. Grems Q a ioo 233 Varying the Amount of Yeast. The experiments with varied amounts of yeast were repeated. Gold Medal and White Poppy were the flours used for this series. By the sponge test, it was estimated that 200 cc. of water was necessary for Gold Medal Flour and 175 cc. for White Poppy. 1/4 cake of yeast (3+ grams) was used for the first baking and the amount was increased 1/4 cake in each succeeding baking until two cakes were used. White Poppy is a soft winter wheat flour. The Gough has a tendency to soften during fermentation. Unless carefully manipulated, it does not yield a good shaped loaf. Since the purpose of this test was merely to determine the effect of yeast upon the two flours, « simple method of procedure was adopted. The dough was given but two risings, one in the mixing bowl and one in the baking pans. In each case, it was allowed to double its bulk. A soft flour is supposed to require a shorter period of fermentation than a hard flour but this has not held true in these tests. Results « (1) With one exception due to poor yeast which permitted the growth of other organisms, winter wheat flour required a longer period of fermentation than the spring wheat flour. Up to one cake of yeast, the total period of fermentation of winter wheat in each baking exceeded that of spring by twenty-five minutes. With more than one ‘cake, the ~340 difference was not so great. No's 6 and 8 (Winter Wheat), requéred ten minutes longer, No. 5, oix minutes. (2) Interesting results occurred in No. 7 of both spring and winter wheat. In.ithese loaves, poor yeast was used. It had been kept over from the day before and was slightly discolored. One of the cakes had been opened but was again carefully wrapped in tin foil. This was used with the winter wheat flour. In twenty minutes, the dough haé more than doubled its bulk. Its appearance indicated an unusual fermentation. TIarge gas bubbles were formed which were worked out with difficulty. After the dough was placed in the baking tins, it was ready to bake in fourteen minutes. The loaf was coarse in texture, unsymmetrical in shape, with a rough uneven crust as shown in photograph 7.. There was no perceptible difference, however, in flavor. The loaf from spring wheat flour, baked at the same time, required fifty minutes in the first rising and thirty-eight in the second, en increase of twenty-ejght minutes over the time required in the previous baking when less yeast was used. (3) fhe decrease in the total time of rising was the same for both spring and winter wheat. The greatest difference, sixty-five minutes, occurred between the loaves with one-fourth and one-half of a cake of yeast. With one half and three fourths of a cake, there was a difference of twenty-five minutes; with three-fourths of a cake and one 2350 cake, of twenty minutes. With more than one cake, greater irregularities occurred which may be accounted for by the difference in the condition of the yeast. No's. 5 and 7, Spring Wheat, with one and a fourth end one and three-fourths cakes, required a longer time than those of the previous baking. The total decrease in the period of fermentation from one fourth of a cake to two cakes was an hour and ten minutes for spring wheat and an hour and twenty five minutes for winter wheat. (4) The volume tended to increase with the increase in yeast. The total increase was greater for spring wheat than for winter. The former increased 24%, the latter 14.4 &. Nos. 4, 5, and 6 of winter wheat with one, one and a fourth, and one and a half cakes of yeast were of the same volume. No. 6 and 7 of spring wheat, with one and a half and one and three fourths cakes were the same. With the latter, this was due to the yeast. Ho. 5 of spring wheat showed a decrease in volume. This required a little longer to rise than the preceding loaf, hence the condition of the yeast may account for this also. With the winter wheat, however, there was a decrease in the period of fermentation in each case, so some other factor must have entered in. (5) The ratio of weight to volume tended to increase = 360 with the increase in the amount of yeast, and was greater in the spring wheat bread than in the winter wheat bread. (5) The bread from spring wheat flour was of finer texture than that from winter wheat flour. The increased smount of yeast did not produce a coarser texture, unless the dough was allowed to become too light. Photograph 9, shows the effect of too long a fermentation upon winter wheat flour. The gluten had become softened to such an extent that the loaf conld not keep its shape. The loaf from spring wheat flour which was given the same treatment, though coarse in texture retained a eypmetrical form. - oe @# # ¢© @ @ m > ® © © @ ee @ j& & MECHANICAL ENGINEERING DEPARTMENT M.A. C. Vel 8 ol 380 Baking Tests with Liquid Yeast. Liquid yeast is subject to so many variations that it ie difficult to obtain uniform or definite results from it, as the following tests will show. Its strength and activity are influenced by temperature, ege,cleanliness, etc. The yeast used in these tests was made after Miss Florence E. Dudley's recipe*. 14 cups of potato 2 quart water 2 ounces of sugar (4 tablespoons) + cake of yeast. Boil the potatoes in the water until done. Strain and add the sugar and, when cooled to luke warm, the yeast. This should be ready for use in from two to six hours. The bread will retain its moisture longer if the potatoes are used, but good results may be obtained with potato water only. Four tests were made. Vor the first three, the yeast was made with potato water and + cup of mashed potato, for the last, potato water only was used. The yeast was made in the afternoon and was used the following morning, by which time only a few bubbles of gas were rising and there was no evidence of a more vigorous action having taken place. 175 cc. of yeast, the amount of liquid required for White Poppy Flour was used. The dough seemed to require more moisture, so 5 cc. of water was added. * Florence BE. Dudley. Flour and Yeast in Bread. Jour. of Hame Econ. Vol. 4, Now 3, Pe 255. -39- The same amount of yeast and 25 cc. of water was used for the spring wheat flour, Gold Medal. The dough was given two risings as in the previous tests. The spring wheat dough required an hour and twenty minutes for both risings, while winter wheat required an hour and forty minutes. The volume of the loaf from winter wheat flour was larger than it has been in the previous tests with short process bread, and was almost equal to that of the loaf from spring wheat flour. The ratio of weight to volume exceeded that of the spring wheat loaf. The loaf from winter wheat had more bloom to the crust and was a better shape than usual. In the other baking tests, the crust had been poor in color and character, lacking the bloam of that of the spring wheat bread. The texture of both was good. In the next baking, the dough was given three risings. Innorder that there might be no variation in the yeast, it was made fresh, started with compressed yeast and used the next morning as before. By morning, a very vigorous ferment- ation had taken place, there being two or three inches of foam on top. Notwithstanding the apparent activity of the yeast, the period of fermentation was very much longer than in the first test. It was longer for winter wheat than for spring, five hours and thirteen minutes for the former, three hours and sixteen minutes for the latter. Each had been given the same treatment. Excess of carbon dioxide seems to indicate exnaustion of the yeast. The volume of the spring wheat loaf “40e showed an incease over that of the previous baking, while that of the winter wheat showed a decrease. The ratio of weight to volume increased for spring wheat and decreased for winter wheat. The texture of winter aheat was poor, that of spring fair. Another test was made in which the dough was given three risings. In order to determine if the cause of the increase in the time of rising was due to exhausted yeast, this time, the yeast was made in the morning and used after it had fermented about five hours. As in the previous test, a very vigorous action was taking place, However, the dough required a still longer period of fermentation, five hours and forty-six minutes for spring wheat, seven hours and fifteen minutes for winter wheat flour. The volume of the spring wheat loaf was the same as in the previous baking, that of the winter wheat was smaller than before. The ratio of weight to volume decreased in both cases. The texture of each was fair. In the next test, the yeast was made without potato and used the next day. Since the extra rising did not improve the quality of the bread, it was omitted. The total period of fermentation for spring wheat dough was two hours and forty- eignt minutes, for winter wheat, three hours and thirty-eight minutes. The volume of each increased. The ratio of weight to volume was higher for winter wheat than for spring wheat and exceeded that of the previous tests exceptuhere potato was used. There was very little difference in the texture oA4le of the two loaves, which was the best of the four tests. Results « | (1) These experiments confirm the conclusions drawn from the long process series, that when potato or potato water is used with winter wheat flour, the bread is more nearly like that from spring wheat flour in volume and in texture. (2) The average loss per cent in fermentation and in baking was less than in the previous tests. (3) No satisfactory explanation suggests itself for the increased period of fermentation of the dough from winter wheat flour in same of these tests. (4) Bxcess of carbon dioxide seems to indicate exhaustion of yeast. (5) Though liquid yeast yields excellent bread, its variability in strength and activity makes it difficult to obtain results in experimental work. ture ‘Ce et, af, — aimee a ee ee o43- Temperature Tests. Same tests were made to determine the inner temperature of the dougn at different times while baking, in order to learn if spring and winter wheat flour differ in this respect. Short process bread made with liquid and with compressed yeast, and long process bread to which 100 grams of potatoes had been added, were used for this purpose. A thermometer was inserted in the middle of each loaf, the initial temperature recorded and the thermometer read every fifteen minutes. A gas oven was used for the baking because the temperature is more easily controlled than that of the electric oven, and the thermemeter may be read through the glass without opening the oven door. The bread was baked forty-five minutes. In some of the experiments, the initial temperature of the oven was 180° ©. This was allowed to rise gradually to 190° © during the first fifteen minutes, to 200° C during the next fifteen minutes, and to 220° C during the last fifteen minutes. In some of the experiments, the order at ° wes reversed. The bread was placed in the oven 220 C and the temperature allowed to fall gradually to 180° Cc. Results - (1) The temperature of winter wheat dough tended to rise a little more rapidly in same of the tests than that of spring wheat dough, but the ultimate temperature was the game. In most cases, this rise was due to the inability of o44. the dough to support the thermometer, the winter wheat dough having a tendency to soften during fermentation. After being placed in the oven, the thermometer fell a little to one side where the temperature was higher than in the middle of the loaf. (2) There was very little change in temperature the first fifteen minutes, the average rise being about two degrees when the initial temperature was 180 . No. la Winter wheat is an exception because of the slipping of the thermometer. With an initial oven temperature of 220 ©, the temperature of short process bread was higher than that of long process bread at the end of the first quarter of an hour. (3) The inner temperature at the end of the half hour was higher in both long and short process bread, when the initial oven temperature was 220° » than when it was 180. (4) The initial temperature of the oven did not affect the final temperature of the loaf in short process bread. In long process bread with potatoes, there wae a rise of 0.5 when the initial temperature was 220 ~ (5) The final temperature of the loaves in which 100 grams of potato was used was lower than that of the loaves in which no potato was used, the former being 95 ° and 95.5 , the latter 98°. This suggests a longer baking for loaves in which much potato is used. Table 7 e Inner Temperature Tests. — tnitial” Yemperature Temperature Temperature temperature at end of at end of at end of Flour No. Yeast 4 on ist. 15 min. 2nd.15 min. last 15 min ou ’ L © e eo e @ = _ __Gentigrade 180 - 190 C. 190 = 200 C, 200-220 C Winter e e e @ Wheat la Compressed 31 42.5 88.5 98 Spring ° ° ° ° Wheat Ib " 32 34 87 98 Winter ° ° ° e Wheat 2a Liquid 32 33 65.5 98 Spring ° ° e | e Wheat 2b " 32 33 61 98 Winter ° ° ° ° Wheat 3a Dry with 31 33 67 95 100 gms. Spring ° ° ° ° Wheat 3b Potato 31.5 34 66 95 a a — — —_ te att a 220 200 - 190 190-180 a eae — — — Winter ° ° ° ° Wheat 4a Compressed 32 62 93 98 Spring ° ° 0 ° Wheat 4d ad 33 46 93 98 oe — —— ee — Winter Dry with ° ° Wheat 5a 100 gs. 30 32.5 ° 84° 95.5 Spring ° ° Wheat 5b Potato 30 32° 17-5 95.5 -46e Tests for Loss in Moisture. Some tests were made to determine and compare the moisture loss in bread from spring and winter wheat flour made with the different yeasts. Two loaves of bread from both spring and winter wheat were made with compressed yeast. In the first baking, 200 cc. of water was used with spring wheat flour, 175 oc. with winter wheat flour; in the other,the water was increased 15 cc in each. The long process bread with dry yeast contained 100 grams of potato. The compressed yeast loaves with 200 cc. and 175 cc. of water, as noted above, and the long process loaves were kept eleven days and were weighed every two or three days. The compressed yeast loaves with the larger amount of water and the Liquid yeast loaves were kept nine days and weighed every day. In order to make a fair comparison, the total loss in weight in grams and in percent was determined for each loaf at the end of six days. In the loaves with compressed yeast baked April 19th, the sixth day fell on Sunday, so the average from the twenty-fourth to the twenty- sixth was taken. The total loss for the entire period was computed for each loaf. Results e (1) The loss percent in weight at the end of six days, with one unaccountable exception in the case of bread ~47 = from liquid yeast, was greater for spring wheat than for winter wheat bread. (2) Of the two bakings with compressed yeast, the lose percent in weight was the same for spring wheat, 6.97%, while for winter wheat, the loaf containing the greater amount of water showed the greater loss, 6.40 %, the other being 5.37%. At the end of nine days, the loss for both spring and winter wheat was greater in the loaves containing more water, than in those with a less amount at the end of eleven days. Spring 8.86 # and 8.81 4; winter 8.13 @ and 6.52%. (3) At the end of six days, the long process bread with potato showed a lower loss percent in spring wheat bread and a greater loss percent in winter wheat bread than in that with compressed yeast in which the dough wae of the same consistency. (200 cc.of water for spring, 175 cc. for winter wheat flour). This seems inconsistent with the other results, hence may be due to error in the original weight of the loaf of winter wheat with compressed yeast. (4) The bread made with liquid yeast showed a lower loss percent for spring wheat than for winter at the end of six days, 3.52% spring, 3.65 % winter. At the end of nine days, however, the loss percent for spring wheat exceeded thet for winter. Spring 5.06 %, winter 4.92 %. These percentages may be due to experimental error. The loss percent with liquid yeast was less than with compressed and dry. The loss during baking and fermentation was also less. o48e (5) The greater loss in moisture in spring wheat bread may be due to the fact that it contains more moisture than winter wheat bread, hence has more to lose, also that it is of larger volume, hence has a larger evaporating surface. -_ © Ff je © $e ». «© e@© - @ @ -— ep ¢- @ @ + it eo ef @ * ef @ al =~50= Comparison of Sponge and Straight Dough Method. In one test, a sponge was made instead of a straight dough. One half of the flour was mixed with the other ingredients and the sponge allowed to rise until light. This required about 40 minutes. The rest of the flour was then thoroughly mixed in and the dough placed in the baking tins. In 55 minutes, both loaves had doubled in volume, and were ready to bake. The texture of each was good and very similar. The volume was greater for spring than for winter wheat and the ratio of weight to volume higher; the volume for spring wheat being 1400 cc., for winter 1250 cc.; the ratio for the former 2.74, for the latter 2.53. These results were compared with those made of bread from a straight dough in which the same amount of yeast, 10 grams, was used. The volume of the loaves from both spring and winter wheat increased 25 cc. The ratio of weight to volume increased in each case. The loss percent in fementation and baking was almost the same in the winter wheat loaves, there being but 0.02 % difference. The loss in spring wheat was 0.32 % higher in the loaf made fran the sp Oo. nge. The total period of fermentation for spring wheat was 1 hour 25 minutes for the straight dough and 1 hour 35 minutes for the sponge. The sponge was probably allowed a longer time than was necessary in the first rising. The total -51- period of fermentation for winter wheat was 1 hour 50 minutes in the straight dough and 1 hour and 35 minutes in the sponge. Fron this one test, which does not afford sufficient data from which to draw conclusions, the period of fermentation for winter wheat seemed to be shortened when @ sponge was made and the quality of the bread improved. With spring wheat, equally good results were obtained fran a straight dough. nti Table 9. Comparison of Bread Made with a Sponge and with a Straight Dough. Flour Kind Weight Weignt Ratio Loss in Time of of of of Volume of fermenta- rising Dough dough Hot Loaf Weight tion and Score gns. gms. to Vol. baking ist end 8» Spring Sponge 566.9 510.2 1400 2.74 56.7 10.0 89 40 min. 55min. * straignt572.1 516.7 1375 2.66 55.4 9.68 87 50 * 35 * Winter Sponge 540.6 492.2 1250 2.53 48.4 8.95 89 40 " 55 * ® straight546.5 497.7 1225 2.46 48.8 8.93 82 khr. 50 * =520 Varying the Number of Risings. A few tests were made in which the bread was given two, three and four risings and the results compared. Accurate data was not obtained so general results only will be given. Lack of time prevented the repetition of the experiments. The volume of winter wheat dread increased with the increase in the number of risings. With the four risings, however, the texture was not so good as with two or three. The volume of spring wheat increased with the third rising, but decreased with the fourth. In the latter case, it did not have time to double its bulk. Scoring or Judging Bread. In scoring the bread, Miss Bevier's score card was used*, Revised Score Card of Miss Bevier. General appearance 20 Size 2 mere 20) Oru los Character Depth Flavor 35 Odor Taste Lightness 15 Crumb 30 Character (20) Coarse - fine Tough - tender Texture Moist - dry Elastic or not Color ) (5) Grain (Distribution of gas Total 100 *University of Illinois Bulletin No. 25, p. 41. -53~ General appearance is placed first not because it is considered most important but because it gives the first impression. Flavor is given under two heads because sourness may often be detected by the odor before it is detected by taste. Bread should have a sweet nutty flavor similar to the wheat grain. Ligntness consists of many elements, relation of weight to volume, size, presence or absence of holes, crumbliness, etc. Brands of Flour Used, The flours used in these experiments were selected because they were available. The purpose was not to test one flour against another but to work with such as were typical of spring and winter wheat. Method for Winter Wheat Flour. When the experimental work with spring and winter wheat flour was completed, recipes for long and short process bread were worked out from the data obtained, in quantities sufficient for a family baking. Bread from soft winter wheat flour has a tendency to crack while baking. This is due to the softening of the gluten, which may be caused by too -54- soft a dougn, too long a period of fermentation, or by allowing the dough to become too light. The consistency of dough which gave the best results was that which could be worked without sticking to the hands, or which could be kneaded with but a slight sprinkling of flour on the kneading board. Good results were obtained from dough which had doubled its buik in both risiggs, but when over light, a poor shaped loaf with poor texture was produced. To avoid over lightness, it is well to bake the loaf before it has quite doubled its volume. If, by chance, it has become too lignt, it should be baked at a higher temperature, or kneaded and allowed to rise again. Since a long period of fermentation softens the giutin, short process bread is better for winter wheat flour than the long process. However, the availability of the dry yeast often makes it desirable to use the letter method. After repeated experiments with varied amounts of flour in the sponge, it was found that that which contained a smali amount of gelatinized flour gave the best results. Some of the soft wheat flours yield a crust of a dull gray color. If milk be used as a part of the liquid, the crust will have & dDloom equal to that of spring wheat flour. The effect of potato or potato water upon winter wheat flour has already been mentioned, 55 Recipe for Long Process Bread. 1 pint of potato water lL pint of milk 3 quarts of flour (?) (Measured before sifting) 2 tablespoons of sugar 2 tablespoons of shortening 1 tablespoon of sait i cake of dry yeast. Soak the yeast in enough luke warm water to cover it. Make a batter with the potato water and 1 cup of flour. A more active fermentation will set in if the potato water be mixed with the flour while boiling hot. Add the sugar, and when cooled to luke warm, the yeast. | 9.99 84.09 . 66 5.01 22 uten flour, not true to name............--.-..6-- | 8. 57 16. 36 3.15 70. 63 1.29 - If, as often happens, it is desirable to blend two kinds of wheat in order to obtain a flour with the average of their qualities, the grains are usually mixed before milling. Sometimes the miller, or even the baker, mixes two kinds of flour, but such a proceeding seems to be regarded by the users of flour as less satisfactory because it gives less uniform results. Tests for quality.—Very complicated chemical tests are necessary to determine the exact quality of a flour, but there are certain general rules by which a good bread flour may be judged offhand. In general, the flour housewives prefer is white with a faint yellow tinge. After being pressed in the hand flour should fall loosely apart; if it stays in lumps it has too much moisture in it; when rubbed between the fingers it should not feel too smooth and powdery, but its individual particles should be vaguely distinguishable; when put between the teeth it should “crunch” a little; its taste should be sweet and nutty, without a suspicion of acidity. Wholesale bakers usually demand a more granular, darker flour and one with a greater power of absorbing water than is ordinarily chosen for household use; they also make careful baking tests with each fresh lot of material, and as each barrel which leaves the first-class mills is individually numbered, it is pos- -sible to trace back to their source any undesirable characteristics if they should be noted. Housekeepers who buy flour under fancy trade names have less opportunity of knowing the character of the product, nor does it ordinarily seem worth while to make baking tests for the small quantities purchased for home use; but an intelli- gent housekeeper who wishes to know the quality of the flour she is buying could easily learn from the dealer or the miller the char- acter of different brands and could use samples to compare their bread-making qualities in her own kitchen before buying her supply for the season. Possible impurities of wheat flour and the ways in which they may be avoided.—Certain impurities may accidentally occur in a bag of 389 14 BREAD AND BREAD MAKING. grain or the flour made from it. They consist mainly of seeds of other plants, some of them harmful to color or flavor, and of blighted or molded grain. Modern methods of sorting and cleaning the grain in well-conducted mills almost eliminate the danger of foreign seeds and careful methods of storing make the dangers from molds and other fungus growths much less than formerly. Careful milling pro- cesses also tend to remove such accidental impurities as bits of sand, earth, or metal which occasionally slip in. Of course flour which is in good condition when it leaves the mill may deteriorate if it is not properly cared for. All such products are attractive fields for molds and bacteria, and in their growth these “minute organisms may spoil the flavor and bread-making qualities of flour, Dampness and darkness are very favorable to their growth, hence dry, well-lighted storerooms are the best for flour. Damp, dark tellars should not be used for storing any cereal products. The color of flour, like many natural colors, fades more or less during storage and the flour becomes whiter. RYE. _The grain of rye is darker in color than that of wheat, but is other- wise similar in appearance. Rye flour differs from wheat flcur in flavor, the liking for the one or the other being a matter of preference. It differs, however, in another way and in an important particular — its gluten has not the same elastic, tenacious quality and does not yield so light and well-raised a loaf. Although this fact and its dark color make it less popular than wheat, it is second in importance as a breadstuff. It is more easily raised than wheat, especially in cold countries, and therefore generally has a lower market value. In many parts of Europe it practically replaces wheat among the poor and in army rations. When it is milled entire, as it usually is, it contains more protein than wheat flour, but is probably less com- pletely digested. Wheat and rye flour are often used together in bread making. BARLEY AND OATS. These cereals are so seldom used in bread that a short description of them will suffice. In general structure their grains are not unlike those of wheat and rye, but their composition differs noticeably. In both barley and oats the bran makes up a higher percentage of the entire grain than in wheat. Both oats and barley on an average contain less moisture than wheat. They do not contain any true gluten (which appears in wheat and rye), and although their other nitrogenous ingredients make them comparatively rich in proteid nutrients, they do not yield a light, attractive loaf. Bread made from them also contains a large proportion of relatively indigestible cellulose. 389 BREAD AND BREAD MAKING. 15 CORN, OR MAIZE. This cereal, generally known in the United States as Indian corn, and on the continent of Europe as maize, is a native of America. It is commonly grown in North and South America, Africa, India, China, and southern Europe, especially Italy and the Balkan regions, and is slowly being introduced into other European coun- tries. The hull of thekernel is thin and tender, the endosperm abundant and mealy, the germ comparatively large. The diagrammatic drawing of a section of a kernel of corn (fig. 5) shows the dis- tribution of the several parts and the relative proportion of-each. Figure 6 shows the character of the cells making up the skin and testa, membrane, and endosperm. Each cell has anouter wall of cellulose varying somewhat in thick- % ness and character in the different parts pio, 5piagrammatic section of grain of of the grain. Within the cell is a com: a,Skinandtesta; b, membrane; ¢, proteid network, the cell nucleus, the — %™™% # endesperms /, seutelium. starch and other products of cell activity being embedded in this protoplasmic material. The character of the cell contents varies in made i m the household by adding shortening, milk, eggs, etc., to the dough, or by modifying in some way the process followed. Sometimes baking powder of some sort is used as a leavening agent instead of yeast, and the form of bread called ‘‘ baking-powder biscuit,’”’ or by some similar name, is the result. An interesting variety of bread made without leavening is known as “Maryland” or ‘‘beaten” biscuit. A rather stiff dough is made from flour and water, or milk, with shortening and salt added. It is kneaded and then beaten or pounded, being frequently turned over and over until it looks light and puffy. The 389 . BREAD AND BREAD MAKING. 2% biscuits are then formed and baked. The folding and pounding of the dough incloses small quantities of air in numberless little blisters. These expand in baking and make the biscuit light and porous. The different kinds of bread from other grains than wheat, as ‘“‘corn bread,’ ‘‘ brown bread,” ‘‘rye bread,” ‘‘gems,’’ etc., which are made in many households, vary somewhat in different regions, but they all follow the same principles which govern the bread making from wheat flour—that is, the flour or meal is mixed to a dough with water or milk, and some leavening substance is generally added to make the dough porous. Eggs, sugar, and shortening may be added, and sometimes spices, chopped nuts, or raisins mixed in, so that the varieties of bread become numerous. UNLEAVENED BREADS... The most interesting of these is perhaps the Passover, bread, which has been used during Passover week by orthodox Jews from the time of Moses until now. It is simply a mixture of flour and water, baked in round cakes until it is dry and hard, and is not unlike plain water crackers. Pilot bread, or ship’s biscuit, is another simple preparation of flour and water so cooked that it can be kept for any length of time. Crackers, or biscuits, as they are often called, especially in England, are also a variety, or, more correctly, numerous varieties of unleavened breads. Milk, butter, lard, spices, dried fruits—anything or everything desired to give them a particular consistency, color, or flavor—is mixed with the flour and water, and the dough is then passed through ingenious cutting machines and quickly baked in a hot oven. Such crackers are dry and therefore a concentrated form of nourishment. ~ . The original Graham bread, made without yeast from Graham meal according to the receipt of its inventor, and not to’be confounded with raised Graham bread, is made by kneading the flour and water thoroughly and allowing the dough to stand several hours before baking. It is heavier than ordinary yeast bread, but still has a few “holes” in it, due probably to fermentation started by bacteria acci- dentally present in the flour or the air. It is sweet and by no means unpalatable, but probably the nutritive value of its protein is lower than Doctor Graham supposed. So-called raw-whreat breads are on the market which are apparently made by pressing the clean and macerated grains into small cakes. Such foods, it is claimed, tend to counteract a tendency to consti- pation. Gluten bread, as its name implies, contains the gluten of the flour from which more or less of the starch has been removed. To make it, strong flour and water are made into dough, which is pressed and 389 28 BREAD AND BREAD MAKING. strained under a stream of water until the starch has been worked out; it is then kneaded again and baked. It makes a light, elastic loaf, frequently prescribed for diabetic patients from whose diet it is considered desirable to exclude starch. (Unfortunately not all the so-called ‘gluten flours” on the market have as much of the starch removed as their names or descriptions imply, and diabetics should be guided by the advice of an experienced physician or analyst in their choice of brands. Some of the diabetic foods now on the market have been recently studied at the Connecticut Agricultural Experi- ment Station and the analysis ior true gluten flour given on page 13 was quoted from its report.? Although macaroni, spaghetti, and other wheat pastes occupy a8 very different place in bills of fare, they are so similar to unleavened breads in their ingredients that they may fittingly be mentioned here. They are made by mixing hard wheat flour and hot water into a stiff paste, which is then molded and dried. The wheats most suitable for their manufacture, viz, the ‘‘durum’”’ wheats, were formerly grown mainly in eastern and southern Russia, the Medi- terranean countries, and South America, but recently they have been successfully cultivated in certain sections of the United States, so that domestic pastes are likely to become more and more common in the markets. Noodles, which are only slowly coming into general use in this country, though they have long been popular in Europe, differ from macaroni and the other flour-and-water pastes in having eggs mixed in, and are therefore lighter and richer in protein. BAKING AND COOLING. In the earliest days of bread making the dough was simply put. into the ashes of the fire or on hot stones to bake; then came the ovens heated by a fire within, which are still used to some extent, and finally the elaborately constructed ovens which can be heated or cooled to any temperature by means of furnaces and ventilating devices around them. But whatever the structure of the oven, the changes which the bread undergoes while in it are essentially the same. It goes in a rather solid, uniform mass and comes outa light, porous body of increased volume with a crisp, dark exterior—the crust—and a firm, spongy interior—the crumb. Let us first see what happens in the crumb. This, of course, ‘heats more slowly than the outside; indeed, the moisture which it contains prevents its temperature from rising much above the boiling point of water (212° F.). When first put into the oven the yeast continues working, but a temperature of 158° F. kills it. The gas in the dough, however, still expands, and, forcing its way outward, enlarges. the loaf and aso a Connecticut State Sta. Rpt. 1906, Part II, pp. 153-165. BREAD AND BREAD MAKING. 29. gives it a spongy appearance. The gluten becomes stiffened by the heat, so that even after the gas in the bubble-like pores has escaped the walls still retain their shape. The starch granules and perhaps the protein compounds undergo certain chemical changes which are believed to render them more digestible. Meanwhile, the crust is becoming hard and dark; the heat changes its starch into stiff gum and sugar and dries out the moisture; the brown color is due to chemical changes known as ‘‘caramelization.”” The reason why bread made from bran-containing flours turns so dark during baking is not thoroughly understood, but recent French investigations indicate that it may be due to the action of enzyms on pigments present in the bran. Of course the proportion of crust to crumb varies with the size of the loaf. The accompanying table® gives the relative percentages by weight in loaves of different weight of German bread: Comparative ueight of crust and crumb in bread. Weight | Crumb | Crust in of loaf. | {In loaf. loaf. Grams. | Per cent. | Per cent. 398 Bread No. Lecce. ccc ccc ccc ccc ccc ccc ccc ence cece cece ne escnccccccaccece 55.2 4.8 Bread NO. 2... cc ccc ccc ccc ccc cc wee ccc cc cee cee ccc ence etn enwecescesenes 880 8.7 40.3 Bread NO. 8.0.22. ccc cc ccc ce ccc ce ccc ecw cee ce cece ence ecnceencceees 1,783 64.3 35.7 Bread No. 4.0. ccccccccc ccc cc cccc ccc c ccc ccc cccccccc eens ccersccncensccecacee 1,998 71.2 28.8 The heat in the oven should not be too great, especially at first, or the outside of the bread will harden too quickly and the interior will not be done before the crust is thick and dark; further, the gas expanding in the crumb will be unable to escape through the crust and will lift up the latter, leaving great holes beneath it. To prevent too rapid formation of the crust, bakers sometimes moisten the tops of their loaves before putting them into the oven or have devices for passing steam over them during the baking. The steam also changes some of the starch into a sort of gum on the top of the loaf and gives it the shiny look so often seen in Vienna bread. The same effect can be produced by moistening the top of the loaf just before it is taken from the oven. Cooks sometimes get a similar result by spreading the top of the bread lightly with butter. If the oven is not equally heated throughout, a baker usually puts the small loaves into the hottest part at first, as the crumb of these bakes more quickly and is in less danger of being underdone. When these are baked, the larger loaves, whose crumb has baked gradually in the cooler parts, are moved into the warmer place and their crust is quickly hardened. In some large ovens the temperature is grad- ually raised during the baking; especially is this the case in the ¢ Arranged from Birnbaum’s Das Brotbacken. Braunschweig, 1878, p. 255. 389 80 BREAD AND BREAD MAKING. aerated bread factories. Aerated dough is mixed with cold water, and if it were immediately subjected to a high temperature the crust would form before the interior was more than warmed through. Accordingly, a peculiar oven is used for baking it, one end of which is heated much hotter than the other. Two cylinders, one at cither end of the oven, are connected by an endless chain, on which the bread plates are hung; the dough is placed on the latter at the cooler end, and then is gradually swung over to the warmer end, the speed- being regulated by the time needed for baking. This insures a thorough baking of the crumb, while the extreme heat at the last gives a good, crisp crust. The temperature of an oven and the time required for baking depend upon the size of the loaves. Small biscuits or rolls can stand a much hotter oven and quicker baking than large loaves, which must be heated slowly and long. For ordinary purposes a baker heats the oven to 400° or 500° F. and lets 8 pound loaf bake an hour or an hour and a quarter; small rolls perhaps half an hour. An experienced cook can tell when the oven is hot enough by putting the hand in, but a pyrometer, as a thermometer for measuring high temperature is called, makes a much safer guide. On being taken from the oven, bread should be placed on slats or sieves so that the air can circulate about it until it is thoroughly cooled. By that time all the gas and steam which are likely to escape have done so, and the bread may be put away. Some house- keepers wrap their hot bread in cloths, but this is not advisable, not only because it makes the bread ‘‘taste of the cloth,” but also because it shuts the steam up in the loaf and makes it damp and clammy— an excellent medium for cultivating mold. Of course, as great cleanliness should be observed in handling and marketing bread as in making it. Well-informed bakers appreciate this and many modern bakeries are models of cleanliness. However, in some bakeries bread is kept where the dust and dirt from the street can get to it, or is delivered in dirty baskets or carts. In this way disease germs and dirt may easily lodge on its surface. Because the crust of fresh bread is so dry and hard molds and bacteria may not grow on it as easily as on a moister surface, but this does not greatly lessen the danger of dirty bread, which in most cases is eaten just as it comes from the shop. In Europe this danger is sometimes avoided by slipping the loaves into bags of parchment paper or something similar as soon as they are taken from the oven. Some American bakers adopt similar plans; a frequent one is that of wrapping the bread in paraffin paper or other special paper, which serves the double purpose of keeping out dirt and preventing the bread from drying. 889 BREAD AND BREAD MAKING. $l STALE BREAD. Good fresh bread has a crisp crust which breaks with a snap and an elastic crumb which springs back into shape after being pressed with the finger. Before bread is a day old, however, its texture has changed; its crust has become softer and tougher, while the inside seems dry and crumbly—the bread is “growing stale,” as is said. This was formerly supposed to be due simply to the drying of the bread, but as the loss of water is found by experiment to be compara- tively slight some other explanation is necessary. Various explana- tions have been offered, of which the most interesting seems that given by Boutroux in the work already quoted. He maintains that the apparent dryness is due to a shifting of the moisture from the crumb to the crust. When first taken from the oven the dry crust cools quickly, but the moist crumb retains its heat much longer. As gradually, however, its temperature falls to that of the surrounding atmosphere its moisture tends to distill outward, leaving a compara- tively dry crumb and moist crust. Common experience shows that if stale bread is put into the oven for a few minutes it regains some- thing of its fresh consistency—a crisp crust and moist crumb. This fact would be explained by the reverse of Professor Boutroux’s propo- sition—that is, the moisture is driven back into the crumb. Such warmed-over bread lacks the elasticity of the fresh loaf, and its interior crumbles as easily as before it was reheated. Recent investigations indicate that this is due to chemical changes in the starch, which tends to go back into less soluble form as the bread grows old. In this connection the well-known household plan of putting a piece of bread into the cake box to keep the cake moist may be men- tioned. This end is accomplished probably because the bread gives off moisture more rapidly than the cake and keeps the air in the box too damp to allow the cake to lose much of its moisture. While cake thus kept does not dry as fast as it otherwise would, it loses its fresh taste, probably on account of chemical changes corresponding to those in aging bread. CHARACTER OF BREAD AS RELATED TO THE GLUTEN OF THE FLOUR. It has already been indicated that gluten is the ingredient of the flour on which its bread-making properties chiefly depend, and that gluten itself is not a simple protein compound, but contains two other compounds, glutenin and gliadin. In different kinds of flours not only does the propoftion of gluten to the other ingredients differ, but also the proportion of glutenin to gliadin in the gluten itself. Two flours containing the same amounts of protein compounds when con- verted into bread by exactly the same process may yield bread of en- 389 32 BREAD AND BREAD MAKING. tirely different characteristics because of the different proportions of glutenin and gliadin in the two flours. The gliadin, a sort of plant gelatin, is the material which binds the flour particles together to form the dough, thus giving it tenacity and adhesiveness; and the glutenin is the material to which the gliadin adheres. If there is an excess of gliadin, the dough is soft and sticky, while if there is a deficiency, it lacks the power of expanding. Many flours containing a large amount of gluten and total proteid material and possessing a high nutritive value do not yield bread of the best quality because of an imperfect gliadin-glutenin ratio. This question is of much technical impor- tance in the milling of wheat, especially in the blending of different types of wheat. At the Minnesota Experiment Station considerable study has been made of this and other problems regarding the bread- making properties of wheat, which may at least be mentioned here. Some of the experiments referred to were planned to test the ques- tion whether it is the starch content or the gluten content that de- termines the bread-making quality of flour. In certain cases the pro- portion of starch in a normal flour was increased 10 to 20 per cent by the addition of wheat starch, while in others it was decreased to the same extent, and in still others 10 to 20 per cent of corn flour was added to the wheat flour. The breads made from the flours con- taining increased or decreased quantities of starch were then com- pared with that made from a like quantity of the normal flour. In the experiments in which the proportion of starch was increased by adding either wheat starch or corn flour there was practically no differ- ence in either the size or the appearance of the loaf as compared with that from normal flour. The results of these tests, as well as of. those made in other countries, clearly indicate that it is the gluten rather than the starch content that determines the bread-making properties of the flour. To get other tests the proportion of starch was diminished, not by removing starch from normal flour, but by adding gluten te it. These tests emphasized the fact that it is not the starch content that determines the bread-making quality of the flour, and they also showed that an abnormally large amount of gluten does not yield a correspondingly large loaf. Experiments were also made to determine the relation between the nature of the gluten and the character of the bread. This was done by comparing bread from normal flour with that from other flout of the same lot, from which part or all of its gliadin had been ex- tracted. Dough made from the latter was not sticky, but felt like putty, and broke in the same way. The yeast caused the mass to expand a little when first placed in the oven; then the loaf broke apart at the top and decreased in size. When baked it was less than half 389 BREAD AND BREAD MAKING. 33 the size of that from the same weight of normal flour, and decidedly inferior in other respects. It was about as heavy as the same quantity of rubber. The removal of part of the gliadin produced nearly the same effect as the extraction of the whole of it, and even when an equal quantity of normal flour was mixed with that from which part of the gliadin had been extracted the bread was only slightly improved. Some experiments have recently been made at the Ontario Agri- culture College ¢ to determine what kinds of flours were best adapted to making milk biscuit with baking powder, and the conclusion reached that soft flours, 1. e., those in which the gluten was not too strong, made biscuits that were tenderer and more easily handled than strong flours. LOSSES OF MATERIAL IN BREAD MAKING. In whatever way bread is made there is always some loss of mate- rials in the process beyond that of the flour and dough accidentally lost in the mixing and molding, and these losses are especially notice- able in bread made with yeast. In experiments carried on at the Minnesota and New Jersey Agricultural Experiment Stations it has been estimated that anywhere from 1.5 to 8 per cent of the nutrients in the flour may disappear in this way. The yeast plants require a certain amount of nitrogenous material for their growth, but fortu- nately feed to some extent on the amid compounds, substances of less nutritive value than protein, and thus occasion only slight loss of valuable food material. A small proportion of the fats also disap- pear, probably volatilized by the heat of baking. The greatest loss occurs in the carbohydrates. It has been seen that during the process - of fermentation part of the starch is changed to carbon dioxid and alcohol; in the later stages small amounts of volatile acids are also formed from the decomposition of carbohydrates. In tests in which care was taken to prevent loss the equivalent of 1.68 per cent of the carbohydrates was lost in this way. When bread is less carefully made the loss is likely to be much greater. Of course part of these losses are inevitable, and the superior lightness, flavor, and keeping qualities of well-made yeast bread more than compensate for them. Evidently the art of producing a well-raised and at the same time the most nutritious loaf depends on letting the fermentation continue just long enough to avoid sogginess and heaviness, and no further. | IMPERFECTIONS IN BREAD. The heaviness or sogginess such as was just referred to is one of the common and most undesirable faults in bread. As has been aAnn, Rpt. Ontario Agr. Col. and Expt. Farm, 34 (1908), pp. 242-247. 889 34 BREAD AND BREAD MAKING. pointed out, it may be caused by the use of flours whose gluten is too weak to absorb the water put into all the dough, or, to state it in another way, by the use of too much water in proportion to the flour; by too little or by too poor yeast; or by insufficient kneading, rising, or baking. Heavy bread is popularly considered to be very pro- ductive of digestive disturbances. When chewed it rolls itself into solid lumps, which might readily hinder the action of the saliva and gastric juices. Occasionally the crumb of fresh bread breaks when cut, instead of separating cleanly under the knife. According to Jago,? harsh, dry flours, not sufficiently fermented, may be the cause of this, or the dough may have lost its tenacity by being overworked. Another common fault in bread is a crumb full of large, irregular holes instead of the small, even pores which it should show. These occur in overkneaded or overraised dough; or, if they are found just below the crust, they mean that the oven was too hot and that the crust formed before the carbon dioxid had finished expanding. Sometimes bread makers are troubled by what is known as “sticky”’ or “‘slimy’’ bread. In such cases bread three or four days old takes on a light-brown color and a peculiar taste and odor. Gradually, too, it becomes sticky or slimy until it may be pulled into strings, sometimes several feet in length. The trouble appears to be caused by the common potato bacillus (Bacillus mesentericus vulgatus), a mirute organism which finds its way into the materials of the dough, survives the baking, and, growing in the bread, causes it to decom- pose. Experiments made at the Wisconsin Experiment Station? show that the bacilli enter the bread with the yeast, which in the cases investigated was a variety of the compressed yeasts ordinarily on the market. It was also proved that the bacilli will survive the heat of baking. Accordingly, if yeasts are not carefully made such trouble may occur at any time, but especially when the weather is warm and favorable to the growth of the bacilli. The best safe- guards are to keep the bread in a cool place and to bake only as much as can be consumed within a day or two. Not infrequently, especially in damp weather, mold forms on the outside, or even in the inside of bread. Mold, like yeast, is a minute plant whose spores (or seeds) are floating about everywhere in the air, ready to settle down and grow wherever they find a moist, suit- able home for themselves. The best practical way to protect bread from them is to keep it in a dry, air-tight box. But all these faults seem insignificant compared to that dread of all housekeepers and bakers, sour bread. This is due to lactic, or, —_ @The Science and Art of Breadmaking, William Jago. London, 1895. 6 Wisconsin Sta. Rpt. 1898, p. 110. 389 BREAD AND BREAD MAKING. 35 in the worst cases, butyric, acid given off in the growth of undesirable bacteria which accidentally find their way into the dough from the air, the water, or in some other way. A little acid is not necessarily harmful, as was seen in the discussion of bread made with leaven and barm; but when the acidity is very pronounced or even accompanied by putrefaction (developed in company with butyric acid) then something is radically wrong. Possibly the vessels in which the bread was made were not thoroughly cleaned after the last using and some of the undesirable bacteria got into the dough from them; or perhaps the yeast contained an undue proportion of these bacteria; or, if the latter were found only in normal quantities, possibly the yeast itself was weak and was quickly exhausted. The trouble may be due to the fact that the dough was allowed to stand too long after mixing, the yeast ceased working, and the dangerous bacteria which grow best in the presence of acetic acid, such as occurs after alcoholic fer- mentation has ceased, had gotten the upper hand. If none of these things are at fault, the undesirable bacteria may have come from the flour itself. Such troubles are, fortunately, very rare, and if bakers and housekeepers guard against all the other dangers they are rea- sonably certain to make sweet bread. If bread grows sour with age, it has probably caught the undesirable bacteria from the air, just as it catches mold. Very rarely, however, bread perfectly sweet at first grows sour before the bacteria in the air have had a chance to get at it. The only possible explanation for this is that the bacteria have managed to survive the baking and are growing luxuriantly in undisputed possession of the good thinys in the bread. Soda is often used by housekeepers in bread to prevent souring, and in small quantities does not injure the flavor of the bread. In breads made from special flours which contain no true gluten—oatmeal, barley, etc.—it is convenient in the production of a sweet, well-raised loaf. Besides the acid-producing bacteria, various others sometimes occur in bread, mostly harmless, but some of them very curious in their effects. Most striking among these is the Aficrococcus prodigi- osus, 8 minute organism which makes blood-red spots in the dough and whose presence gave rise to many interesting superstitions during the middle ages. NUTRITIVE VALUE AND COST OF BREAD. In order to decide which of several foods furnishes the most actual nourishment for a given cost, it is necessary to know not only the actual price and the nutritive ingredients of each, but also their relative digestibility. The one which is found to furnish the greatest amount of digestible nutrients for a given sum will be the cheapest, provided both are equally wholesome and desirable otherwise. 389 86 BREAD AND BREAD MAKING. CHEMICAL COMPOSITION. The chemical composition of the finished loaf differs somewhat from that of the original ingredients, but depends primarily upon that of the flour from which it is made. If milk and butter (or lard) are used in mixing the dough, as-is commonly the case, their nutrients are, of course, added to those of the flour; but when only water and flour are used the nutrients of the bread are simply those of the flour. In either case, however, the proportions of the nutrients in the bread are smaller than those in the flour, because a considerable part of the moisture from the water or the milk used in mixing the dough is present in the bread after baking; that is, a pound of the bread would contain less of any of the nutrients than a pound of the flour, because the proportion of water in the bread is greater. The following table, which gives the results of analyses of patent wheat flour and several sorts of bread made from it, illustrates this point: Composition of flour and of bread made from it in different ways. . r Carhohy- Materials, Water. | Protein.| Fat. drates. | “Sh. ‘ Per cent.| Per ceni.| Per cent. | Per cent. | Per cent. Flour... 0. ccc ce ccc cee cc cnc cee cece ec cenaes 10. 11 12. 47 0. 86 76. 09 0. 47 Bread from flour and water........0.........0....0-. 36. 12 9. 46 . 40 §3. 70 32 Bread from flour, water, and lard.................... | 37.70 9.27 1.02 51.70 31 Bread from flour and skim milk.............0....... 36. 02 10. 57 .48 62.63 -30 The increase of water in the bread hardly needs explanation, since it is evidently due to the water added in making the dough. The decrease in protein and carbohydrates is in part only apparent and is due to the increased proportion of water, but is in part real, as was explained on page 33. It has been estimated that the alcohol gener- ated by the yeast plant is equivalent to about 1 per cent of.the total weight of the bread. Earlier investigators reported a small per- centage of alcohol (less than 0.5 per cent) in the bread, but according to Snyder’s investigations no appreciable amount of the alcohol remains after baking. Part of the starch in the crust has been changed into dextrin, and that in the crumb has become gelatinous or partly soluble. The gluten, as has previously been pointed out, has taken definite shape. This really means that it has coagulated very much as the white of an egg does in boiling. The increase of fat in bread made with lard is of course due to the latter ingredient and the increase of protein in skim-milk bread of course comes from the protein in the milk. It is apparent that two kinds of bread from the same lot of flour may differ according to the method used in making the bread. On the other hand, two loaves of bread made by exactly the same proc- ess, but from different lots of flour of the same grade or brand, do 389 BREAD AND BREAD MAKING. 37 not necessarily have the same composition, because of a possible varia- tion in the flours. The chemical composition of wheat is not a fixed characteristic, different kinds of wheat varying widely in this respect. Furthermore, the composition of the same sort of wheat varies with several factors, such as climate, rainfall, and the soil in which it is grown. It is evident, therefore, that general statements regarding the composition of flour and bread can hardly be universally accurate. Since durum wheat has become a common crop in many regions of the United States much interest has been manifested regarding the value of durum flour for bread making and other household purposes. As is the case with other types of wheat, the quality varies in different cultural varieties. The many analyses which have been reported. show that on an average durum wheat and the flours made from it do not differ materially from similar products of other wheats. For instance, in an extended comparison made by the Bureau of Plant Industry ¢ it was found that the durum wheat flours tested showed, on an average, 12.61 per cent protein, and Northwestern spring wheat flours 13.01 per cent, the range in the two cases being much the same, and further, from studies of the proportion of gluten and of gluten constituents in durum flour, the conclusion was, reached that on an average it did not materially differ in these respects from flour from other varieties of wheat. The results of numerous bread-making tests at agricultural experi- ment stations and elsewhere indicate that bread of good quality and appearance may be made from durum flour, and judging by data gathered by the North Dakota Agricultural Experiment Station,>® housewives who are familiar with the use of durum flour consider it satisfactory for bread making and other household purposes. In color, durum flours from different varieties of wheat show a wide range, some flours being white and others rather dark. It seems fair to say that in general it is yellower than flour from the varieties more commonly milled. COMPOSITION OF BREADS AS COMPARED WITH SOME OTHER FOODS. To show the difference in the proportions of the different food ingredients in various foods, it may be well to compare the analyses of bread and other foods as given in the table on page 38. The sam- ples of wheat bread here represented are grouped together according to the kinds of flour used; that is, all those given under Minnesota hard wheat were made in exactly the same way from flours specially milled from the same lot of wheat, and the differences between them are due only to the differences in the milling processes. The Oregon and @U.8. Dept. Agr., Bureau of Plant Industry Bul. 70. 6 North Dakota Sta. Spec. Bul. 19. 389 38 BREAD AND BREAD MAKING. Oklahoma flours were likewise specially ground and the breads made in the same way as those from the Minnesota flours. Thus, if the figures for entire-wheat bread from these three classes of flours are compared, the differences may be accounted for entirely by differ- ences in the original grain and not at all by differences in milling and baking. It should be remembered, however, that grains grown in the same locality may vary considerably in composition from year to year, so that the figures here quoted might not always be strictly accurate. They do, however, represent correctly the general differ- ences between the breads from various types of wheat. Composition of various sorts of bread and some other food materials. Num- | Food material. analy- Refuse. | Water. | Protein. | Fat. Carbohy “| Ash. ses. Wheat bread: From hard Scotch Fife spring wheat, Minnesota— Per cent. | Per cent.| Per eent.| Per ct. | Per cent. | Per et. Graham flour. 2.2... 0c. e eee ccc ccc cele w ee ne ceee 47.20 7. 76 1.27 42. 82 0. 95 Entire-wheat flour............!0 002.02. cee c eae 49. 15 7. 45 1.14 41. 73 . 52 Standard patent flour....... 0/0000... ee eee 44.183 7.75 90 46. 90 .32 Second patent flour..... 22...) 0. ele eee 42,10 7. 75 v2 40. 16 20 First patent flour.............)........ ‘eee eee eee 44. 40 7. 48 71 47.14 27 From Oregon soft winter wheat— | | Graham flour. ..............00) cece ec elew eee eeeee 38. 55 6. 11 1.12 52. 68 1.54 ientire-wheat Mour...........2/.00..... lessee. 39. 95 5.70 | 1.09 52. 39 . 87 Straight grade flour..... 0.2...) occ ee cece cee 34. 95 5. 41 . 89 57. 85 90 Fyor Oklahoma hard winter | wheat— | Graham flour................-/.0.0000. | weeeeeeee 42. 20 10. 65 1.12 44. 58 1. 45 Entire-wheat flour. ........../... 0. ccelecceaeeees 41.31 10. 1. Of 46. 11 Straight grade floyr...........{........ \ eee eeeee 37. 65 10. 13 . 64 51.14 44 Straight prade flour with 14 per cent bram..............0)0 0 cece cee ce eee 43. 20 9. 50 . 4 45. 55 91 Straight grade flour with 7 per | | | Cent germ... oe. cece cee cee eee Sa weeecees 38. 00 11. 07 1.13 49. 12 . 8 From miscellaneous flours— High grade patent............)........ te weeccee 32. 9 &7 1.4 56.5 5 Standard grade patent......../........ ‘eee eeeeee 34.1 9.0 1.3 54.9 7 Medium grade patent.......005 00... \ cee eeeeee 39.1 10. 6 1.2 48.3 9 Low grade patent............/........ Lecce ences 40.7 12.6 Lil | 44.3 1.3 White bread, average. ............ WB. 85.3 9.2 1.3 5a. 1 Ll Rolls... 2... c ccc cece cece eee | 35. 7 8.9 1.8 52.1 1.6 Crackers. .........0 0-2. cece eee ene WL {oo .. eee... 6.8 10.7 &8 71.9 1.8 Macaroni.................0.. 0000. Vl f....... ee 10.3 13.4 a) 74.1 1.3 Cora bread (Johnnycake)............. 6 oe... eaee 38.9 7.9 47 46. 3 2.3 Rye bread........02..0...00.---00005- Qi l eee. 35.7 9.0 6 53.2 1.5 Rye-and-wheat bread................ 1 '.......... 35. 8 11.9 .3 61.5 1.0 Beef, ribs: Edible portion. ...........0...... 15 |.......00. 55.5 17.5 26.6 |.......... 9 As purchased. ...................-. 8 16.8 39. 6 12.7 30.6 |.......-.- 6 Veal, leg: Edible portion. ...............02. se 71.7 20.7 6.7 |.......ee- 11 AS purchased. ........ 2... eee eee 18 11.7 63. 4 18.3 5.8 |.....--6-- 1.0 Mutton, leg: Edible portion. .................. 1 63. 2 18.7 17.5 |..c.ceeeee 1.0 As purchased. ......0.....0....00. 15 17.7 51.9 15. 4 14.5 |.......... 8 Cod steaks: Edible portion. .................. 1 |.......2.. 79.7 18.7 re 1.2 As purchased. ......02............ | 1 9.2 72. 4 17.0 A 1.0 Hens’ eggs: Edible portion....... deceecaceaee GO |.....-...- 73.7 13.4 10.5 |.......... 1.0 AS purchased..................00. eee. 11.2 65.5 11.9 9.8 |.......... 9 Butter... ccc cee eee eee eees Le esewscees 11.0 1.0 85.0 |.........- 3.0 Milk, whole... .... 200.22 ee eee ole \ eeceeeee 97.0 3.3 4.0 5.0 7 Potatoes: ° Edible portion. .................. 136 |.......... 78. 3 2.2 wl 18.4 1.0 As purchased..............0.00..- [0002008 20. 0 62. 6 1.8 wl 14.7 8 Apples: Edible portion. .................. 29 |... ooo ee 84.6 .4 5 14.2 3 As purchased. .......2......020.2./0020000- 25.0 63.3 3 3 10.8 3 Chocolate, as purchased.............. 7 5.9 12.9 48.7 30. 3 2.2 | 389 BREAD AND BREAD MAKING. 39 _ From various dietary studies it is reckoned that the average man at moderately active work requires about a fifth of a pound of protein and so much of fats and of carbohydrates in his daily food that the - available energy of all together wil equal 3,500 calories. The more physical work he does the more food he will need. Milk contains the three classes of nutrients, but not in the proper proportion for adults in health. The large quantities of milk’ which a man would have to drink in order to obtain the necessary amount of nourishment make it inconvenient for exclusive use. Meats and cheese are rich in pro- tein and fat. Vegetables are especially rich in carbohydrates. Bread contains both protein and carbohydrates, but in order to get the requisite amount of protein from it one would have to take more carbohydrates than is otherwise necessary. The combination of bread with such material as meat or cheese, which is rich in \ protein, makes a much better balanced ration. Turning again to the bread analyses, it will be seen that while the breads made from graham, entire-wheat, and lower grade patent flours contain shghtly more protein than the finer grades the difference is often extremely small, and differences between the composition of the original grains are more important. Thus graham flour made from Oregen soft winter wheat produced bread containing 0.7 per cent more protein than straight grade flour from the same grain; but straight grade flour from Oklahoma hard wheat yielded bread with almost two-thirds again as much protein as the Oregon graham flour. Evidently, then, the ordinary housekeeper who buys flour under a brand name which tells little or nothing of its origin is about as likely to get a high percentage of protein in a patent as in a graham or an entire-wheat flour. Fortunately the differences are likely to be very smali in any case. In considering the differences in the composition of bread made from various flours, it should not be forgotten that the amount of water which a loaf contains affects the percentage of nutrients present. The quality of its gluten allows Oklahoma hard-wheat flour to absorb and retain more moisture in bread made from it than Oregon soft wheat, for instance, and the percentage of protein and other nutrients contained in the former is proportionately smaller. Similarly, the percentage of protein and other nutrients in bread made from patent flours is relatively smaller than that in graham bread, because the former absorbs more water. The figures given for the average composition of many samples of bread, rolls, crackers, and macaroni are interesting, because they rep- resent better than the others, perhaps, the average of such goods as found in the open markets. The average composition of 198 samples of white bread is just about the average composition of the breads prepared from specied fours in the first part of the table. The reason 389 40 BREAD AND BREAD MAKING, ° why crackers and macaroni seem to be richer in nutrients than bread is of course that they contain less water. Corn bread, like corn meal, - contains Jess protein and more fat than wheat bread and flour. Of course the amount of fat in any kind of bread varies with the amount of shortening used. Judged by their composition, all breads are nutritious foods, and too great stress should not be laid on the varia- tions in composition between the different kinds. So much popular discussion has been aroused in Jate years regarding the relative values of some of them, however, that a more detailed account of the matter may not be out of place here. GRAHAM, ENTIRE WHEAT, AND STANDARD PATENT FLOUBS. The nutritive value of these three classes of flour and the breads made from them has been extensively investigated by Snyder at the Minnesota Agricultural Experiment Station and by Woods at the Maine Agricultural Experiment Station. Graham flour, strictly speaking, is simply wheat meal; that is, the entire grain ground to a powder. It has sometimes been made by removing the outer branny portions of the kernel and grinding this separately from the inner parts, afterwards combining the two, as it was thought that the efforts to grind the naturally coarse material with the rest of the wheat had a deleterious effect upon the bread-making qualities of the flour. It is now commonly made by crushing and grinding the whole of the kernel at once, without bolting or sifting. When thus prepared it contains the same ingredients as the wheat itself and in the same proportions. Even the most successful attempts at fine grinding, however, still leave it fairly coarse and with a large pro- portion of branny particles. To overcome this objection more or less bolting is frequently resorted to. Much of the flour sold as graham has been thus treated, though, of course, such a product is not really graham flour such as Graham advocated. The term ‘‘whole wheat’’ or ‘‘entire wheat’’ seems rather inexact and suggests flour practically identical with the graham. The flour thus designated, however, is said to be made often by removing the branny outer covering and grinding the remainder. By such a method some of the outer portion of the wheat kernel would be retained in the flour. So far as can be learned much of the so-called whole-wheat flour is not so ground, but is made by mixing patent grade, middling, and low-grade flours with considerable of the germ. Whole-wheat flour is not so coarse as graham nor so fine as the white flours. The flour most widely used is that known as straight patent, or standard patent, or family grade. Although this flour contains neither the germ nor the bran of the wheat, in modern exhaustive milling nearly 73 per cent of the kernel is recovered in it. 389 BREAD AND BREAD MAKING, 4] The following table gives the results of the analyses of flours and breads prepared from special lots of wheat at the Minnesota Experi- ment Station, and each group represents strictly comparable materials the differences in which are due only to differences in the process of milling and not at all to difference in the wheat used. Composition of flours and breads as shown by experimental studies. Carbohy- Material. Water. | Protein. Fat. drates, Ash. Minnesota wheat flour (fresh material): Per cent.| Per cent. | Per cent. | Percent. | Per cent. First patent... 2... leccecccecees.. 10. 55 11. 08 1.15 76.85] = 0.37 Second patent........000 0D ttt 10. 49 11.14 1.20 76. 75 42 First clear..........0.000000 I 10. 13 13. 74 2. 20 73.13 - 80 Standard patent.......000000 0777271 iittt 10. 54 11. 99 1.61 75. 36 - 50 Becond clear.............0. 00s 10. 08 15. 03 3.77 69. 37 1.75 weed dog”... EE 9.17 18. 98 7.00 61. 37 3. 48 Entire wheat..........00 00D 10. 81 12. 26 2. 24 73. 67 1.02 raham........- 20.0. cee 8.61 12. 65 2. 44 74. 58 1.72 Oregon wheat flour (fresh material): tandard patent... 22.2... 8. 94 7. 55 1. 25 81. 82 -44 Entire wheat..............00LIIIDI rn 8. 66 8. 25 1. 67 80. 35 1.07 BOT ete eee eee ween ee ee cence ceeee.., 8.15 8.97 1. 68 79. 48 1.72 Oklahoma wheat flour (fresh material): Standard patent.......... 0... 9. 93 15. 06 -92 73. 57 . 52 Entire wheat............000 000 7. 46 16. 63 1. 64 73. 05 1.22 Graham........ 7.73 16. 81 1.79 72. 35 1. 32 Bread made from patent flour (fresh material): High grade...... 2.2... eee. 32.9 8.7 1.4 56.5 5 Standard grade..........000 00 34.1 9.0 1.3 54.9 7 Medium grade........2.00 0002 39.1 10.6 1.2 48.3 .9 W grade.......-.... 2... 40.7 12.6 1.1 44.3 1.3 Bread ymade from Oregon wheat flour (water-free asis): Standard patent............ eee ceeeeechec cee, 8. 32 1.37 88. 93 1.38 Entire wheat............ 00. DIITIIIIIIIIIIIIS Ds 9. 49 1. 82 87. 24 1.45 Graham eee ee le 9. 94 1.83 85. 72 2.51 | Bread made from Oklahoma wheat flour (water-free asis): Gtandard patent... 16. 24 1.02 82. 03 -71 Entire wheat......200 00000002022 12iitttt lee eeeeccae 18. 06 1.77 78.75 1.60 Graham... 2... | beeeeeeeee 18. 43 1.94 77.12 2.51 Comparing the three grades of flour from the same lot of wheat, it will be noticed that in each case the Proportion of protein was largest in the graham and smallest in the standard patent flour, the entire wheat being between these two. On the other hand, the proportion of carbohydrates was smallest in the graham and largest in the standard patent flour. The breads from the different flours, made in such ways as to afford comparison, bear the same relation to one another as the flours in respect to the proportions of nutrients. Thus, in the breads made from different grades of patent flour, that from the high-grade flour, which had the lowest protein content, had the least protein, while _ that from low-grade flour, which is the richest in protein, had the most. This is true of the breads of which the analyses are given in the table, even though the proportion of water is highest in the bread from the low-grade flour ; if the computations were based upon the dry matter of the breads the differences would be still larger. In the case of breads made from the different grades of Oregon and Oklahoma wheat the values given are for dry matter, in order that the 889 s 492 BREAD AND BREAD MAKING. comparison may be absolute. These data show that in each case the graham bread had the most protein and the least carbohydrates, as was the case with the flours. Considering that these two nutrients are not present in flour in proper proportions for a well-balanced diet, there being an excess of carbohydrates and a deficiency of protein, it might seem from such a comparison of composition that the coarser flours would be the best. Before an adequate discussion of relative nutritive value is possible, however, the digestibility of the three flours must be determined. DIGESTIBILITY OF DIFFERENT KINDS OF BREAD. A knowledge of the digestibility of any food material is of prime importance, for two reasons: In the first place, unless a food is com- pletely digested a portion of it does not serve the body as nutritive material, because only that part of the food which is digested and absorbed from the alimentary canal can be thus utilized; and, in the second place, some indigestible materials may act as irritants in the alimentary canal, and while they may stimulate the excretion of the digestive juices they sometimes increase peristalsis too much, thus hastening the contents along too rapidly to permit complete absorption, with the result that nutritive material which otherwise might be absorbed and serve to nourish the body is lost along with the indigestible materials. In estimating the nutritive value of a food material it is therefore necessary to consider not only its com- position but also the proportions of its different nutrients that are digested and utilized. . The next question then is, What kind of bread furnishes the greatest amount of digestible nutrients? Among the earliest and most famous experiments made to test this question are those con- ducted by Meyer and Voit, of Munich, about thirty years ago. They used different kinds of rye and wheat bread, and reached the conclu- sion, which all later work has verified, that the digestibility of bread depends largely upon its lightness. The work done during ten years at the Maine and Minnesota experiment stations throws much light on the comparative value of different kinds of bread. Upward of 100 digestion experiments have been made with young, healthy men, with bread from different grades of flour ground from hard and soft wheats from Indiana, Michigan, Minnesota, Dakota, Oklahoma, and Oregon. Im all these investigations great care was given to the securing of different grades of flour from the same lot of wheat, to the production of bread from the flours, and to all other details of the experiments, in order to secure uniformity of conditions, and thus insure fairness and reliability in comparison. The results @U.8. Dept. Agr., Office of Experiment Stations Buls. 85, 101, 126, 143, 156. 389 . \ BREAD AND BREAD MAKING. 43 of these experiments, therefore, give very definite information regard- ing the relative digestibility of bread from different grades of flour. The larger number of these experiments were made with graham, entire wheat, and standard patent flours from wheats from different sections of the country. The averages of the results with these three grades of flour give the following as the proportions of nutrients that were digested from the different flours, these factors being commonly termed coefficients of digestibility: Standard patent flour, protein 88.6 per cent and carbohydrates 97.7 per cent ; entire-wheat flour, protein 82 per cent and carbohydrates 93.5 per cent; graham flour, protein 74.9 per cent and carbohydrates 89.2 per cent. The digestibility of the fat was also studied in some cases, but the quantity of fat in bread is too small to permit of accurate tests of its digestibility, and for the most part the results were believed to be inexact, and are therefore omitted. This is a matter of no im- portance, however, as bread is not considered as @ source of fat in the diet. The very common custom of eating butter or some other ' fat with bread is in reality but a method of supplying this deficiency. With all the subjects, and with all kinds of wheat thus far tested, the uniform result was that the digestibility of the standard patent flour was the highest, that of entire wheat the next, and that of graham the lowest. | The nutritive value of the mineral matters in the bran-containing flours has not yet been satisfactorily determined. Within a few years detailed research into the phosphorus compounds of flours, begun at the New York State Agricultural Experiment Station and later carried on in various laboratories, has revealed a new substance called phytin, which seems to have a distinct physiological action. Interesting and valuable as such work js, more studies are needed before the influence of these constituents of bran and of other parts of the wheat berry can be definitely understood. Probably too much stress should not _ In any case be laid on the importance of the extra amount of phos- phates and other ash constituents of bran. It should be remembered that fine flour also contains such ash constituents, and it is not unlikely that they are in forms which are more available or useful than those in the bran, even if finely ground. These mineral sub- stances are of undoubted value, but there are few experimental data to show the amount of different ash constituents necessary for main- taining the body in health. It is doubtless safe to say that the ordinary mixed diet of children and adults furnishes an abundance of mineral matter. A certain “ bulkiness”’ in the diet .is desirable, such as is supplied by the crude fiber of plants, and the coarser flours, owing to the particles of bran or some other property, often increase tke peristaltic action of the intestine and thus tend to prevent con- 3u9 | 44 BREAD AND BREAD MAKING. stipation. They may at times otherwise aid digestion; hence for persons in need of a laxative, bread made from such flours may often be preferable to white flour, but for a healthy person its claim of superiority on the basis of nutritive value is hardly warranted at present. Certainly no plea can be made for them on the ground of economy, for entire-wheat and graham flours are not cheaper than white flour. On the other hand, it must not be forgotten that all flours are wholesome and palatable, and that variety in bread is just as pleasing as variety in meats, vegetables, and puddings. The housekeeper may therefore wisely use all the different kinds of flours here discussed to give variety to the diet and please the taste of differ- ent members of her family. As has been said, well-made bread of any kind is a very nutritious food, and the differences between the various kinds are too small to be of practical importance to persons of healthy digestions and comfortable circumstances. Experiments similar to those with the flours just discussed have been made with different grades of patent flours. It was found that the percentages of digestibility differed very little, and that as far as nutritive value is concerned the cheaper grades are fully as good as the more expensive. The bread made from them is as light as that from the finer flours, but not quite so white and appetizing. Where rigid economy is necessary the cheaper grades can safely be used. A number of experiments have also been made to study the effect of adding germ to patent flour. The digestible nutrients in the flour made with the germ, as found in these experiments, showed a trifle more protein and slightly less carbohydrates than in the flour without the germ. Therefore, practically no gain in nutritive value was obtained by retaining in the flour the germ that is ordinarily removed in the milling. Crackers, macaroni, and various sweet cakes made from white flour have also been tested at the Minnesota Experiment Station, and it has been found that their digestibility was practically the same as that of white bread. Of course all these experiments were made with healthy normal persons, and the results should not be applied too closely to invalids or others of delicate digestion. Moreover, nothing very definite has yet been learned about the ease and quick- ness with which these foods are digested. Bearing these limitations in mind, however, it may safely be said that simple, well-made crackers and cakes, at least when eaten in moderate quantities, are digested by persons in health with much the same thoroughness as bread. HOT, FRESH, AND TOASTED BREAD. Statements of a popular nature are frequently met with regarding the unwholesomeness of hot bread. The fact that bread is hot has doubtless little to do with the matter. New bread, especially that 389 ~—" AO re 8 er me ee ~~ Tw 29 BREAD AND BREAD MAKING. 45 from a large loaf, may be readily compressed into more or less solid masses, and it is possible that such bread would be much less finely masticated than crumbly, stale bread, and that, therefore, it might offer more resistance to the digestive juices of the stomach. However, when such hot bread as rolls, biscuit, or other forms is eaten in which the crust is very large in proportion to the crumb this objection has much less force. Little difficulty is then experienced in masticating the crumb, and it is doubtless usually finely divided. As far as is now known the changes ordinarily occurring in good bread as it ages do not affect its digestibility unless it becomes so dry as to be unappetizing. When bread is toasted the chemical nature of some of its ingredi-' ents is changed and the carbohydrates at least become more soluble and presumably more easily digested. The ferments and bacteria which may have survived the baking or which have entered the bread later are also killed if the toasting is continued long enough; this may be of considerable advantage to persons of delicate digestion. Owing to its dryness, toast is more likely to be well masticated than fresh bread. These facts and the further one that perhaps owing to its crispness and greater flavor it is often more appetizing than bread explain why toast is so suitable for invalids. Of course its advantages are greater when it has been well toasted throughout than when only the outer surfaces have been subjected to the action of the heat. PLACE OF BREAD IN THE DIET. As previously pointed out, bread contains from 35 to 40 per cent of water. Since the remainder, about 60 per cent at least, is nutri- tive material, bread is really one of the most nutritious of the common foods, but few others equaling it in this respect. Bread supplies a large amount of carbohydrates, a moderate amount of protein, a small amount of mineral matter, and almost no fat. Since there is relatively an excess of carbohydrates and a deficiency of protein in wheat, bread could not serve alone for proper nutrition of the body, because an amount of bread sufficient to supply the requisite protein would furnish much more carbohydrates than necessary. In a mixed diet this discrepancy is of little importance, because the defi- ciency of protein is made up by such foods as meat or cheese. Bread and milk forms a much more suitable diet than bread alone. Where bread forms the whole or the main part of the diet, as it does among large numbers of the poor, the deficiency of protein is of much more consequence. Most methods of increasing the protein content of bread which have been suggested have a tendency to increase the cost of the bread too much. The use of skim milk instead of water for mixing the dough does not increase the cost of the bread very 389 46 BREAD AND BREAD MAKING. materially, but {t does add appreciably to the protein content. A comparison of skim-milk bread with water bread made from the same flour, as given in the table on page 36, shows that the skim milk increased the protein about 2 per cent. SUMMARY. Cereals of one kind or another have always made an important item of human food, and of all the forms in which they have been used bread has proved the most satisfactory, palatable, and con- venient. To prepare the grain for bread making it is usually cleaned, crushed, and sifted into a fine soft powder, which is called flour. The nutritive value of bread depends not only on its chemical composition, but also on its digestibility, and digestibility in its turn seems to depend largely on the lightness of the loaf. It is the gluten in a dough which gives it the power of stretching and rising as the gas from the yeast expands within it, and hence of making a light loaf. Rye has less gluten proteids than wheat, while barley, oats, and maize have none, so that they do not make a light, porous loaf like wheat. It is possible that of the various kinds of wheat flour those containing a large part of the bran—entire-wheat and graham flours—furnish the body with more mineral matter than fine white flour; but it is not certain that the extra amount of mineral matter furnished is of the same value as that from the interior. portion of the grain. They do not yield more digestible protein than the white flours, as was for a time supposed. It seems safe to say that, as far as is known, for a given amount of money, white flour yields the most actual nourishment with the various food ingredients in good proportion. It should be remembered, however, that all kinds of bread are wholesome if of good quality, and the use of several kinds is an easy means of securing variety in the diet. The raising or leavening of bread is usually brought about by letting yeast develop in it. These minute plants feed upon sugar in the dough and in their growth give off alcohol and carbon-dioxid gas, which (particularly the carbon dioxid), expanding with the heat, force their way through the dough and thus lighten it. In order to give the yeast a better chance to work, the dough is usually “set to rise” for some hours before it is put into the oven. There are many methods of growing yeast at home or in the bakery, but the dry and the compressed yeasts now in the market seem to give equally good results with so much less labor that their use, in the United States at least, is becoming practically universal. 389 BREAD AND BREAD MAKING. 47 The lightness and sweetness of bread depend as much on the way in which it is made as on the materials used. The greatest care should be used in preparing and baking the dough and in cooking and keeping the finished bread. Though good housekeepers agrce that light, well raised bread can readily be made with reasonable care and attention, heavy, badly raised bread is unfortunately very common. Such bread is not palatable and is generally considered to be unwholesome, and probably more indigestion has been caused by it than by all other badly cooked foods. As compared with most meats and vegetables, bread has prac- tically no waste and is very completely digested. It is usually too poor in protein to be fittingly used as the sole article of diet, but when eaten with due quantities of other foods it is invaluable, and well deserves its title of ‘‘the staff of life.” 389 O OQ tismany 2 alenens & % Sines ** neal iii”