HYGIENE OF DIGESTION 2$$ 



than the crumb, or white portion, as it resembles sugar. Bea- 

 ten breadis the most digestible, like the hoe cake and johnny- 

 cake and other unleavened breads. Yeast bread comes next 

 in digestibility. Baking powders, if they contain alum, 

 and soda, if not thoroughly neutralized by sour buttermilk, 

 are injurious even to the healthy. It is quite possible 

 that the depression and nervousness caused by innutrition 

 from trying to live on such abominations as soda biscuit and 

 grease-soaked food, are often the forerunners of drunken- 

 ness and other misfortunes that a small amount of intelli- 

 gence in the kitchen would have prevented. 



464. Yeast belongs to the class of plants called fungi, 

 which can live in darkness, and have neither leaves nor blos- 

 som. Most plants get nourishment from the soil, air, and 

 water, but yeast and other fungi derive their sustenance 

 from vegetable or animal matter in process of decomposi- 

 tion. Yeast plants are microscopic cells of oval shape, and, 

 like other plants, require food in liquid form. They can- 

 not absorb dry or solid food. Their most suitable food is 

 sugar. The flour of wheat contains starch, a small amount 

 of which is converted into sugar by the diastase which lies 

 next the bran. Yeast grows best at a temperature of from 

 70 to 80. A slow growth at a lower temperature favors 

 the development of other micro-organisms, which make the 

 yeast unhealthy and produce bad flavors. With a high tem- 

 perature its growth is rapid and of extremely short duration. 

 Fermentation may go through several stages ; in the first 

 stage, or alcoholic fermentation, the yeast decomposes the 

 sugar, splitting it into alcohol and carbon dioxid gas. 

 This is the stage for bread-making, the gas causing the 

 bread to rise. In the second stage, or vinegar fermentation, 

 alcohol is changed to acetic acid the acid in vinegar. 

 Hard wheat has more gluten than other wheat, and the 

 bubbles formed in its flour will not break easily. Why 

 does bread from such wheat rise well ? Why is bread set 



