EXPERIMENT 78: PROTEIN IN FLOUR.—Make a stiff dough, using 2 tablespoonfuls of bread flour and about 1/2 tablespoonful of water. Knead well, and allow to stand for 20 minutes. Then tie the dough in cheese- cloth, place it in a bowl of water, and knead for a few minutes.

Pour a little of the water in a test tube; drain the remainder of the water from the dough. Add more water to the bowl. Again knead the dough under the clean water.

Examine the material in the cloth. What is its color? Feel and pull it. Put a little on a plate to dry, and bake some in the oven. Examine after drying and baking. How has it changed in size by heating?

Test the water in the test tube for starch.

GLUTEN.—The material left in the cloth consists largely of protein. If flour is mixed with water, gluten is formed from the two kinds of protein that are to be found in all wheat flours. Gluten is yellowish gray in color, is extremely elastic and sticky, and, if moistened and heated, expands to many times its original bulk. These qualities of gluten are most desirable for good yeast bread; hence, the more protein that flour contains, the better it is for bread making. As has been stated, some flours contain more protein than others. The protein of wheat as well as of other grains is incomplete, hence grains need to be supplemented with other kinds of protein food.

WHEAT FLOUR.—The quantity of protein in flour is not only dependent upon the portion of the wheat kernel used in making the flour (see Difference in Wheat Flours), but also upon the kind of wheat from which the flour is made. Spring wheat, the seeds of which are sown in the springtime, usually contains more protein than winter wheat, the seeds of which are sown in the fall. The flour made from spring wheat is called hard wheat flour or bread flour. This flour is creamy in color, rather gritty in feeling, and when pressed in the hand does not retain the impression of the fingers. Flour made from winter wheat is called soft wheat flour or pastry flour. This is white, very fine and velvety in feeling, and easily retains the impression of the fingers.

On account of the greater quantity of protein in bread flour, this flour absorbs more moisture than pastry flour. Less bread flour than pastry flour, therefore, is required for the bread mixture. If bread flour is substituted for pastry flour, its quantity should be decreased,—2 tablespoonfuls for each cupful.

DRY YEAST SPONGE.—It is generally agreed that compressed yeast is more satisfactory for bread making than dry yeast. By the use of the former, the method is shorter, and the "rising" can take place during the daytime and be checked at the proper time. The use of dry yeast, however, is necessary under some conditions. For this kind of yeast cake, the yeast is made into a stiff dough by mixing it with starch or meal, and is then dried. In the dry state, yeast plants do not grow, but remain inactive until they are subjected to conditions favorable for growth. In order that dry yeast may begin to grow, it is necessary to make a sponge of the materials used in bread making. A sponge is a batter containing half as much flour as is required for the stiff dough. A thin mixture rises more quickly than does a stiff dough; hence the advantage of "starting" dry yeast in a sponge.

The growth of yeast is somewhat retarded by salt and spices. Sugar in small quantity aids rapid growth; much sugar delays the rising of bread. Much fat and many eggs also make the process slower. In the preparation of buns, when much fat and sugar and many eggs are to be used, it is advisable to make a sponge. These materials are not to be added, however, until the sponge is stiffened. The yeast thus gets a good "start" before the eggs, etc., are added.

BREAD (made with dry yeast) (2 loaves)

2 cupfuls water 1/2 cake dry yeast 2 teaspoonfuls salt 2 teaspoonfuls sugar 1 tablespoonful fat 6 cupfuls (or more) bread flour

Soak the yeast in the water (lukewarm) until softened. Then add the salt, sugar, and fat. Stir until the salt and sugar are dissolved, and the fat is melted. Add one half the given quantity of flour. Beat until the mixture is smooth; cover. Let rise until very porous and foamy. Add enough flour to make a stiff dough; knead; and allow to rise until doubled in bulk. Proceed as for bread made with compressed yeast.

SCORE CARD FOR BREAD [Footnote 109: "Selection and Preparation of Food," by Bevier and Van Meter, p. 82.]—DETERMINING ITS QUALITY

Flavor 35
Lightness 15
Grain and texture 20
Crust (color, depth, texture) 10
Crumb (color, moisture) 10
Shape and size 10
—-
Total 100

QUESTIONS

Under what conditions would dry yeast be used in bread making?

For what reason is bread dough kneaded?

What is the test for sufficient kneading of bread dough?

In what part of the country is spring wheat grown? Winter wheat?

How are the flours distinguished that are made from these different kinds of wheat?

From U. S. Department of Agriculture, Bulletin No. 28, tabulate the percentage composition of winter and of spring wheat flour.

Which contains the more protein; which, the more carbohydrates? Compare the quantity of ash in each.

Knowing the method of leavening, the time required for raising, and the properties of gluten, explain why spring wheat flour is better adapted to yeast breads than to quick breads.

What is the price per sack of pastry and of bread flour?

What is the price per cake of compressed yeast? What is the price per package of dry yeast? How many cakes in a package?