In turn, fill a test tube with part of each of these three portions and invert in the remaining liquid, taking care not to admit bubbles of air into the tubes. Use cups or tumblers, if no beakers are at hand. While inverting, the test tubes may be covered with the thumb or a piece of stiff paper. Keep at room temperature, and note result after an hour or two. 4. Chill the fourth portion, fill a test tube with the mix- ture and invert as above, and place in an ice-box, or out of doors if it is cold weather. Compare the result with the others after the same length of time. II. Examine under a microscope yeast from an actively fermenting liquid, and make a drawing of a "plant/' III. Observe the action of yeast with the following food materials and account for the results. Use J yeast YEAST 241 cake and J c. liquid in each case. Invert in test tubes as before. 1. Water. 2. Water with | tsp. flour. 3. Milk. 4. Water in which potatoes have been cooked. 5. Water and J tsp. of starch. 6. Water and J tsp. of sugar. B. MAKE SUGAR COOKIES OR GINGERSNAPS. SUGAR COOKIES. 2 tbsp. fat £ ssp. soda j c. sugar J tsp. baking powder If tbsp. egg | c. flour and amount neces- 1 tbsp. sour milk sary to roll A few drops of vanilla✪ Sugar Cookies GINGERSNAPS. j c. brown sugar \ tbsp. cinnamon £ c. molasses 1 tbsp. lemon juice 3 tbsp. fat A little grated lemon rind \ tbsp. ginger 1 c. flour \ tsp. soda Roll as thin as possible. YEAST The compressed and dried yeast cakes sold in stores are usually made from yeast obtained from distilleries. Here the yeast is grown by sowing it in "wort", as it is called, a mixture of crushed grain or mashed potatoes, warm water, and sprouted barley. Under these conditions the yeast plants multiply rapidly. The yeast which collects as a scum on top of the wort is preferred for bread yeast, although the yeast which settles out at the bottom is sometimes used. The yeast is freed from impurities as 242 FOOD STUDY far as possible, pressed to remove the water, and then cut into cakes which are wrapped in tin foil. Starch may be mixed with the yeast before the pressing process takes place. A small percentage of starch helps to keep the yeast, especially in warm weather, as well as making it easier to mix with the flour in bread-making. As the amount of starch used varied from five to fifty per cent, the government recently has ruled that if starch is used in compressed yeast cakes, its presence must be stated on the label. Compressed yeast cakes must be fresh to be in good From Conn's " Bacteria, Yeasts, and Molds In the Home." 1. YEAST FROM A DRIED 2. THE SAME YEAST AFTER YEAST CAKE. A FEW HOURS' GROWTH. condition, and this can be told readily on examination. The cakes should be creamy white, not dark ; uniform in color, not streaked ; a firm, even texture, not slimy ; and there should be no disagreeable odor.

AI-modernized reading of the original text

In turn, fill a test tube with part of each of these three portions and invert in the remaining liquid, taking care not to admit bubbles of air into the tubes. Use cups or tumblers, if no beakers are at hand. While inverting, the test tubes may be covered with the thumb or a piece of stiff paper. Keep at room temperature, and note result after an hour or two. 4. Chill the fourth portion, fill a test tube with the mixture and invert as above, and place in an ice-box, or out of doors if it is cold weather. Compare the result with the others after the same length of time. II. Examine under a microscope yeast from an actively fermenting liquid, and make a drawing of a "plant." III. Observe the action of yeast with the following food materials and account for the results. Use ⅓ yeast YEAST 241 cake and ⅓ c. liquid in each case. Invert in test tubes as before. 1. Water. 2. Water with ⅛ tsp. flour. 3. Milk. 4. Water in which potatoes have been cooked. 5. Water and ⅛ tsp. of starch. 6. Water and ⅛ tsp. of sugar. B. MAKE SUGAR COOKIES OR GINGERSNAPS. SUGAR COOKIES. 2 tbsp. fat ½ tsp. soda ⅓ c. sugar ½ tsp. baking powder 1 tbsp. egg ⅔ c. flour and amount neces- 1 tbsp. sour milk sary to roll A few drops of vanilla GINGERSNAPS. ⅓ c. brown sugar 1 tbsp. cinnamon ½ c. molasses 1 tbsp. lemon juice 3 tbsp. fat A little grated lemon rind 1 tbsp. ginger 1 c. flour ½ tsp. soda Roll as thin as possible. YEAST The compressed and dried yeast cakes sold in stores are usually made from yeast obtained from distilleries. Here the yeast is grown by sowing it in "wort", as it is called, a mixture of crushed grain or mashed potatoes, warm water, and sprouted barley. Under these conditions the yeast plants multiply rapidly. The yeast which collects as a scum on top of the wort is preferred for bread yeast, although the yeast which settles out at the bottom is sometimes used. The yeast is freed from impurities as far as possible, pressed to remove the water, and then cut into cakes which are wrapped in tin foil. Starch may be mixed with the yeast before the pressing process takes place. A small percentage of starch helps to keep the yeast, especially in warm weather, as well as making it easier to mix with the flour in bread-making. As the amount of starch used varied from five to fifty per cent, the government recently has ruled that if starch is used in compressed yeast cakes, its presence must be stated on the label. Compressed yeast cakes must be fresh to be in good From Conn's " Bacteria, Yeasts, and Molds In the Home." 1. YEAST FROM A DRIED 2. THE SAME YEAST AFTER YEAST CAKE. A FEW HOURS' GROWTH. condition, and this can be told readily on examination. The cakes should be creamy white, not dark ; uniform in color, not streaked ; a firm, even texture, not slimy ; and there should be no disagreeable odor.

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