Page:Foods and their adulteration; origin, manufacture, and composition of food products; description of common adulterations, food standards, and national food laws and regulations (IA foodstheiradulte02wile).pdf/284

 which gives a tough consistency to the loaf is most highly regarded both for palatability and nutritive purposes. This form of bread is improperly called French or Vienna rolls in this country.

Unleavened bread is particularly advisable for use in emergency rations for marching soldiers, in logging camps, etc. This bread is compact, comparatively free of moisture and has a high nutritive value. The leavened bread may be divided into distinct classes in respect of the leavening agent employed.

Class 1 is bread in which the leavening agent is yeast. Class 2 is bread in which the natural ferments residing in the flour or wheat are utilized for the leavening agent as in the making of that variety known as salt rising bread. Class 3 includes that form of bread in which the leavening is secured by chemical reagents mixed with the dough. Class 4 includes that variety in which a leavening reagent such as carbon dioxid or air is mechanically incorporated with the dough during the kneading process.

Unleavened bread is also divided into several technical forms. The first class includes the biscuit of commerce, sometimes incorrectly called crackers, and intended to be used soon after preparation. The second class includes biscuits which are intended for long storage and transportation. The third class includes wafers and other delicate forms of unleavened bread for special use. Class 4 is the unleavened loaves which are made most frequently from Indian corn meal and intended to be eaten while still hot. Class 5 includes any miscellaneous unleavened loaves or cakes made in various ways and for different purposes.

In nearly all forms of unleavened bread made from wheat flour the dough is thoroughly beaten, and mechanically mixed or kneaded, in order to make it lighter in color and more crisp and hard after baking.

Yeast.—Bakers' yeast is one form of the ordinary yeast ferments or a mixture thereof producing alcoholic fermentation under proper conditions. All flour contains a certain quantity of sugar which is easily fermented. By the action of the yeast upon this sugar carbon dioxid and alcohol are formed. The particles of carbon dioxid become entangled in the gluten of the wheat flour when it is mixed into a dough and thus make the mass spongy and light. When placed in the oven to be baked these minute particles of carbon dioxid expand still more and produce additional lightness and sponginess of the loaf. The yeast may be propagated from one mass of dough to another, may be used in a moist state or, as is very commonly the case, manufactured in large quantities, and sold either moist or more commonly in a partially dried and pressed cake.

Spontaneous Ferments.—All cereals contain ferments of a character to produce alcoholic fermentation spontaneously under proper conditions. It