Flour mixtures are taken to mean food materials in which the basis is flour to which is added liquid, and a leaven; sugar, butter, and various fruits or condiments may be added also. These mixtures are baked, fried, or steamed. The composition and nutritive value of a flour mixture naturally varies with the ingredients. No general statements need be attempted, but the student should work out the food values of as many of the products as time permits. See also A Laboratory Manual for Dietetics, Mrs. Mary S. Rose, and Bulletin 28, of the Office of Experiment Stations, United States Department of Agriculture.

For the purposes of this book it seems best to take up the experiments on Flour Mixtures as a connected group, while a division is made in the recipes.

Flour Experiments

143. - To 1/4c, bread flour in a bowl, add just enough cold water to make a stiff dough. Knead with a wooden spoon or the fingers for 5 minutes. Cover the bowl with a cheesecloth and allow it to stand for 30 minutes so that the water may develop the full amount of gluten.1

After the dough has stood for 30 minutes, add sufficient cold water to cover the mixture and knead the mass gently but thoroughly in the bowl.

1 At least four different kinds of protein can be isolated, but the most important for us to take account of are gliadin, and glutenin, the essential constituents of "gluten." a. Notice the milky color of the water as soon as the kneading begins.

b. To what is the milky color due?

c. Determine by the iodine test, page 13.

144. - Continue kneading the mass, changing the water frequently until it no longer shows the milky color.

The resultant mass is gluten. Notice the stringy, elastic character.

Notice the color.

Save for subsequent experiments.

Note : Perhaps some of the class have made "gum" by chewing wheat grain and remember the sticky, elastic mass with sweetish taste which results.

145. - To small portions of the washed gluten, apply the following tests: a. Xanthoproteic, page 85.

b. Iodine, page 13.

c. Fehling-Benedict, page 13.

146. - Burn a small portion ; an odor as of burning wool or feathers is noticed.

What material burns with such an odor?

147. - Dry a small piece of gluten with a cheesecloth. Place it on an ungreased pan and bake it in a hot oven.

The mass will expand, but, on removing from the oven, will contract. What causes it to change shape? How can it expand and contract without cracking? To which class of foodstuffs does gluten belong? What are its physical characteristics?

148. - To give the class a more comprehensive idea of gluten, the instructor should contrast the following by preparing gluten or attempting to prepare gluten: a. pastry flour b. rye flour c. entire wheat d. graham flour e. corn meal

Note : These experiments should demonstrate to the class the reasons for the thorough kneading of breads as contrasted with the slight beating of cake after the flour has been added.