50 BULLETIN 123, U. S. DEPARTMENT OF AGRICULTURE. 



YEASTS AND FERMENTATION. 



(1) Experiment on the effect of temperature. Blend one yeast cake thor- 

 oughly in a pint of water to which has been added one tablespoon of sugar. 



(a) Freeze a portion of the mixture, then allow to thaw at room temperature. 



( b ) Boil another portion and cool to room temperature. 



(c) Take a third portion at room temperature. 



(d) Chill a fourth portion. 



Fill bottles from each of the above and invert them on plates. Keep (a), 

 (6), and (c) at 32° to 37° F. and (d) packed in ice during the remainder of 

 the lesson period. Explain results observed. 



Yeast muffins, etc., may be made in the usual way and also with the addition 

 of strained pulp of fruit or vegetables, such as white or sweet potato, apples, 

 squash, or pumpkin, and mashed parsnips. These may be used interchangeably. 



If there is time in connection with the lesson, breads should be made wholly 

 or in part with flours made from bananas, chestnuts, potatoes, soy beans, or 

 such other substances of like vegetable origin as can be secured. 



Some writers on cookery consider such addition as adulterations of bread, 

 but they deserve recognition for the variety thus afforded. 



REVIEW QUESTIONS, LESSON IX. 



1. Describe any mushrooms you know to be edible. 



2. Can you describe any poisonous fungi? 



3. How do mushrooms rank in nutritive value? 



4. What is the source of the various leavening agents used in breads, etc.? 



5. Tell all you can of yeast, its nature, method of use, etc. 



6. What vegetables are sometimes combined with flour for making bread? 



7. In what proportions are cream of tartar and soda used and why? 



8. Mention uses for soda without cream of tartar. 



9. How may foods be guarded from ill effects of molds and ferments? 



10. What form of fungi commonly attack fabrics? 



LESSON X. CONDIMENTAL VEGETABLE FOODS AND FOOD ACCES- 

 SORIES. 



The value of appetizers or food accessories is generally recognized. 

 The words condiment, herb, and spice are used somewhat indis- 

 criminately, but together refer to various vegetable products used in 

 small quantities to add flavor where it is lacking or to develop nat- 

 ural flavors in food. The terms may include such vegetables as 

 radishes and water cress, which are served in their natural state; 

 flavoring materials, such as spices, savory herbs, and extracts used in 

 general cookery; and prepared sauces, pickles, etc., in which some 

 mild-tasting material like watermelon rind usually serves to carry 

 a combination of flavors. In whatever form they may finally appear, 

 the majority of these flavors are due to the volatile oils or similar 

 bodies developed in the plants from which they were obtained. 



The actual quantity of these articles in any one dish is usually so 

 small that their nutritive value can hardly be counted, but neverthe- 

 less they are important, because they may make otherwise insipid or 

 monotonous foods more palatable and so render them more digestible. 



