Elements of the theory and practice of cookery

Either white or whole-wheat bread may be mixed with water, milk, or half milk and half water, as may be preferred. Water bread is sweeter, tougher, and keeps longer than "half-and-half" or all-milk bread. Bread properly made from good materials requires neither shortening nor sweetening, but keeps moist longer if one tablespoonful of shortening (butter, lard, or drippings) is added for each cupful of liquid. 224. These two kinds of bread contain neither soda nor baking-powder. What do they contain that is not used in quick breads ? Does yeast make bread light ? and if so, how ? The first thing to find out is : — 225. What yeast is. — Yeast is a mass of tiny plants, each a single, rounded cell consisting of a sac filled with watery matter. Under a microscope new cells may be seen budding out of old ones, forming branching chains. Each cell, however, lives and grows independently. Sometimes, usually in old yeast, daughter-cells form as spores inside a mother-cell, and burst through the enclosing sac. The home of yeast is on the skin of grapes and on parts of some other plants. A Study of Yeast 226. Microscopical examination. — Examine under a micro- scope a drop of yeast grown in Exp. A (preferably in molasses Is 126 THEORY AND PRACTICE OF COOKERY and water). Note («) the shape of the cells, (6) their walls, (c) granular appearance of cells, if existing. This is more notice- able in old cells. Try to find a cell just budding. Make one or more memory drawings of what you see. 227. The growth of yeast ; experiments. — A. Mix one table- spoonful of flour, one of sugar,i and three-fourths of a yeast- cuke to a smooth paste with four or five tablespoonfuls of cold water. Divide the mixture between three six-inch test-tubes (or three tumblers). Label the test- r-\ tubes a, b, and c respectively. Fill a with boiling water; half fill b with lukewarm water, and stand it in lukewarm water or in a warm place ; half fill c with cold water and keep it at a temperature of 32° F. or below (by placing it in a bowl of cracked ice, or outside the win- ^^^.^ dow on a freezing day). In a fourth ^^^ test-tube, d, put one-fourth of a Fic. ^^^. —Yeast-cells. yeast-cake mixed with water only; treat it like b.^ After fifteen minutes examine all four test-tubes. What do you see on the top of the liquid in b ? What goes on in the liquid ? Let a and c stand for a time where they will be about as warm as /; ; what change do you notice in either of them ? Is there any foam on cH The quantity of foam produced is a measure of the vigor of the yeast. At what temperature does yeast thrive best ? Will it grow at all at 32°? After being frozen and thawed? After being heated to 212°? Will it grow in water alone? B. (To be done during the i^rogress of Exp. A.) Prepare in a generating flask a mixture like the first used in Exp. A, using 1 Adding sugar hastens the growth of the yeast ; for bread-making the sugar in the flour is sufficient. 2 A mixture of molasses and water may be used instead of a flour mixture in this series of experiments. BREAD 127 three or four times the quantity. Arrange an apparatus like that shown in Fig. 14. Or use test-tube h instead of a flask, standing it in a tumbler of warm water. What gas comes from the yeast