MICROBIOLOGY OF FERMENTED FOODS 565 



several distinct advantages over sugar. The lactic acid of the malt 

 insures a " clean" fermentation in the dough, improves the flavor of 

 the bread, causes the color of the crumb to become lighter, and 

 improves the flavor. Unreported data obtained by the writer and 

 experiments reported by A. Wahl* have shown the above statements to 

 be warranted. Bread made with malt extract, instead of sugar, remains 

 moist for a longer time probably because of the 'large amount of dextrin 

 in the syrup. The malt sugar of the syrup ferments more readily 

 than cane sugar and the syrup is rich in yeast food, two factors tending 

 to reduce the amount of yeast necessary and to improve the character 

 of the fermentation. It is doubtful whether there is sufficient diastase 

 in malt syrup to convert so great an amount of starch into maltose as 

 to affect the yeast fermentation, quality, and texture of the bread. 



It is probable that the shortening added to the dough does not affect 

 the character of the fermentation; its principal functions are to improve 

 the texture and the flavor of the loaf. 



It has been found that the quality of the bread is improved and less 

 yeast is required if a small amount of plaster of Paris, calcium sulphate, 

 is added to the flour. Ammonium sulphate possesses a remarkable 

 stimulating effect upon the yeast. If small quantities of this salt are 

 used it all disappears during the rising of the dough. It is assumed that 

 it is taken up by the yeast and converted into protein. One proprietary 

 mixture used by bakers consists principally of a mixture of ammonium 

 sulphate and plaster of Paris. 



The amount of water added will vary with the strength of the flour, 

 weak flours requiring less and giving, therefore, a smaller weight of 

 bread than strong flours. 



The flour and other ingredients are brought to a definite favorable 

 temperature, 25 to 30, before mixing with the yeast. The dough 

 mixing room in modern plants is maintained at a constant temperature 

 and high humidity by means of a thermostat and hygrometer controlled 

 heating and ventilating system. The latter consists of a large fan, 

 heating coils, air humidifying chamber, and air-distributing pipes. A 

 high humidity is necessary to prevent the surface of the dough drying 

 out during its stay in the mixing room. A constant temperature 

 is necessary to insure that the bread will rise on " schedule" time if 

 other conditions are carefully controlled. It is usual to mix the dough, 



* Wahl, A., Journal of Industrial and Engineering Chemistry, 1915. page 773. 



