90 BACTERIA, YEASTS, AND MOLDS 



temperature should be higher in winter than in sum- 

 mer, owing partly to the fact that flour in winter is 

 quite sure to be cold and to require some time to become 

 warm. In winter a temperature of 95° is not too great 

 for the proper raising of the dough, while in summer a 

 temperature of 70° is more satisfactory. In the raising 

 of bread dough it is always far better to use a ther- 

 mometer and to determine the exact temperature. This 

 is rarely done in the ordinary kitchen. It is more com- 

 mon to place the dough near the stove and trust that 

 the temperature will be close enough to that desired. 

 It is not possible, under these circumstances, to depend 

 absolutely upon the results. In the majority of cases 

 the dough is fermented satisfactorily, but bad batches 

 of bread from this cause are a frequent experience of 

 the housewife. To produce uniform results it is quite 

 necessary to use a thermometer, and then the dough may 

 surely be kept within the limits of temperature above 

 mentioned. 



The length of time for yeast to grow in the dough before 

 baking is dependent upon the temperature of the fermen- 

 tation ; but it is important that it should not be too long. 

 If the temperature is low (below 70°), so that it requires 

 a longer time than usual for the dough to rise sufficiently, 

 the texture of the bread is apt to be crumbly and brittle, 

 and a sour taste is very likely to develop, due to the 

 growth of other microorganisms besides the yeast. If, 

 on the other hand, the bread rises too quickly, owing to 

 too high a temperature, an abundance of gas is produced 

 which makes the dough rise rapidly ; but the bread will 

 be inferior in flavor, texture, and color. The best results 



