Foods, their selection and preparation

Yeast. The use of yeast as a leavening agent is discussed in the chapter on "Leav¬ ening Agents.” At present there are three forms of commercial yeast available to the homemaker: compressed, fast dry granular, and dried yeast cakes. Compressed or moist yeast is active and begins developing as soon as food, moisture, and warmth are supplied. This yeast must be kept under refrigeration. The new fast-rising granular yeast also is active and develops as soon as the proper conditions are provided. It can be used like compressed yeast, but in making bread with milk, it is best first to soften this yeast with a small quantity of lukewarm water. This yeast need not be refrigerated and keeps longer than compressed yeast. The dry yeast cakes, consisting of inactive dried yeast cells mixed with corn meal, require a long fermentation period. This yeast, however, keeps longer than any other commercial form of yeast. Because of the speed of fermentation, either compressed or fast granular yeast should be used with soft-wheat flour. Long fermentation weakens the tender type of gluten in soft-wheat flours. If yeast is handled properly, it not only leavens bread but brings about a number of fermentative changes in the dough which help to give yeast bread its particular character and flavor. Salt. Salt is added to bread for flavor, and it also helps to control fermentation. In too large a quantity, salt retards the action of the yeast. Some cooks use slightly more salt in summer than in winter, since warm weather tends to speed the fermentation too much. Salt also seems to have some effect on the gluten in the flour, helping it to stretch without breaking, as the gas from the yeast expands. Sugar. Sugar is not essential to bread¬ making, since enzymes present in the flour can ferment the starch in the flour to sugar. Sugar, however, is quick food for the yeast. From simple sugar the yeast forms carbon dioxide and alcohol. (See page 292.) Less time is required to ferment sucrose (cane sugar) to simple sugar than starch to simple sugar. Any fermentable sugar may be used. In general, the amount of sugar used is just enough to start the activity of the yeast and give a bloom to the crust, but not enough to give the bread or rolls a sweet taste. Too much sugar is objectionable because of its effect on the gluten. It has a marked solvent action on wet gluten and diminishes the water-absorbing power of the flour. In small quantities it is possible that this solvent action may effect sufficient softening to increase the gas-retaining power of the dough and thus indirectly the strength of the flour. Sweet breads have more sugar in the dough than plain breads, but some of their sweetness comes from icings and candied fruits. Fat. As in quick breads, fat in yeast breads improves flavor, gives richness to the bread and makes it tender. It is thought, also, that fat helps to increase volume by making the gluten meshwork more tender, so that the gas can expand it more readily. Fat also helps to make a velvety soft crumb, and helps to prevent the bread from drying out. Any well-flavored or bland fat may be used, such as lard, hydrogenated fats, mild salad oils, margarines, and butter.