BREAD. 442 BREAD. the necessary amount of yeast. Tlie yeast may be added directly or a preliminary ferment may be fonued by niixinj; it with potatoes. If the latter method is employed, the yeast is l)Ut into a thin liquor, formed by mixing mashod potatoes with warn; water, aiid the mi.xlure is allowed to ferment for some time. The advantages claimed for the potato ferment are that the yeast-cells are strengthened by the soluble nitro- genous matter of the potato, which acts as a yeast stimulant and enables a smaller quantity of yeast to hydrolyzc a larger amount of starch. The yeast-celis then act very rapidly on the glu- cose thus produced from the starch and develop the alcoholic fermentation." The proportion of water required to mix with the dough and yeast to form the 'sponge' dejiends upon the quality of the Hour, as the gluten Hours take much more water than the starchy flours, but enough should be added to make the sponge as moist as can be molded readily with the hands. The dough should be thoroughly kneaded, so the yeast will penetrate to every part of the mass. It should then be allowed "to stand in a warm place, for a proper temperature is an essential condition and the alcohol formed by the fermenting action is driven off. The carbon dioxide is also ex- panded. By wetting the loaves before they are put into the oven, the crust is fonued more rapidly, and the too rapid expansion of the dough is checked. Steam is sometimes injected into the oven while the bread is baking, thus glazing the crust and keeping the interior of the bread more moist. Baked bread consi.sts of two portions, the crumb and the crust, which ditTer from each other both physically and chemically. These dif- ferences arc due to the more sudden and intense heat to which the crust is subjected. The action of the heat and of the st<'am rapidly decomposes the starch into dextrin and maltose, which are caramelized by the heat, and so the surface takes on a brown color and a sweeter taste. The ac- companying table shows the chemical difference between the crumb and crust of bread, according to the analyses of German and American investi- gators. That fermented bread is more healthful than unfermentod is now generally admitted by physi- cians. Being porous, it is easily masticated and more thoroughly aerated during the process, so Water Protein Fat CARBOHYDBATES KIND OF BREAD Starcli Sugar Dextrin, etci Ash 46.4 12.5 40.6 13.0 40. G 22.3 8.9 12.3 6.5 9.3 8.9 11.4 .6 .6 1.0 .6 .5 .6 34.2 53.5 40.3 59,2 1.4 4.2 2.5 3.6 8.3 IG.O 8.9 14.0 Bye tread (German) j ^^^^^ Whetit bread (German) ... ^'""1" 49.7 65.3 .3 Wlieat bread (American) { J^^^^j. .4 to the fermenting process. The most favorable temperature is from 70° to 75° F. ; if it is al- lowed to rise above 90° acetic, lactic, and pos- sibly other organic acids are liable to form; in other words, the bread sours, if, on the other band, the temperature is too low, the process of fermentation will not take ])lace. The yeast begins to act upon some of the starch of the flour, changing it to sugar, and then decompos- ing the sugar into carbon dioxide and alcohol. It is not until the second stage is reached, and the gas begins to form, that the action is visible. After the process has gone on for a time, until the whole mass is honeycombed, the dough should be subjected to a second thorough kneading, to break up the large gas-bubbles into many small ones and distribute them evenly through the mass of dough. The thoroughly kneaded mass is next molded into loaves and allowed again to 'rise.' As bread loses a portion of its nutritive properties each time it is molded, the process should not be repeated too often. Bread which has been kneaded onlv once has a sweeter flavor than that molded twice, but its texture is ■coarser and its appearance less attractive. The loss of nutritive valiu' is from that portion of the atarch which is ccmverted into alcohol and gas. When the bread is thorou<jh1v kneaded the sec- ond time it is ready for the oven afterrising. The best temperature for baking lirend is from 4,^0 to 550° v.. so that the interior of the loaf will be at the boiling-point, or 212° V. During the process of baking the starch of the flour is rendered solu- ble by the heat, the fermenting growth is killed, that the starch is more easily acted upon by the digestive fluids. 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 flnger. 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 we nay. This was formerly supposed to be due sim- ply to the drying of the bread; but as the loss of water is foimd by experiment to be compara- tively slight, some other explanation is necessary and various ones have been offered, of which the most interesting seems that given by Boutroux. lie maintains that the apparent drj'iiess 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, how- ever, its temperature falls to that of the surround- ing atmos])here, its moi.sture tends to pass out- ward, leaving a comparatively dry crumb and moist crust. Common experience shows that if stale bread is put into the oven for a few minutes it regains something of its fresh consistency — crisp crust and moist crumb. Such bread lacks the elasticity of the fresh loaf, and its interior crumbles as easily as before it was reheated. This is supposed to be because the starch has undergone a chemical change, the nature of which is not yet clearly understood. Indeed, the whole question of staleness is one about which little has been absolutely proved.
