338 BIOLOGICAL ACTIVITIES OF YEASTS 



to 38° to 40° C. and inoculated with a pure culture of a Mucor or 

 Rhizopus. Mucor Rouxii, Rhizopus japonicus, or other related molds 

 are some that have been used in this process. Sterile air is blown 

 through the mash to develop the mold; the temperature is then 

 lowered and the mash inoculated with yeast. In the Boulard proc- 

 ess,^ a modification of the Amylo process, acid is not added and the 

 mash is inoculated simultaneously with both the mold and yeast. 



Organisms of the Aspergillus flavus-Oryzae group have been used 

 in the manufacture of diastatic preparations in Japan for hundreds 

 of years. An efficient method has recently been developed by Under- 

 kofler and his coworkers ^^ involving the use of certain strains of 

 A. Oryzae. Air is passed up through the perforated bottom of the 

 aluminum pans in which the moistened bran is held. The moisture 

 content of the mixture is about 70 per cent. The temperature rise 

 due to the growth of mold is controlled by the rate of aeration. 

 After about 48 hours' incubation at a little below 45° C, the moldy 

 bran is dried and ground before use, in the same manner as malt. 



Where wheat meal or flour is the raw material, the Balls-Tucker 

 process may be used, employing the naturally occurring amylases 

 in wheat. The ground wheat, before cooking, is extracted with a 

 weak solution (0.5 per cent) of sodium sulphite. This sulphite- 

 diastase mixture is added to the cooked grain to saccharify the 

 starch. 



These hydrolyzates from starchy materials, after fortification with 

 nutrients, are inoculated with suitable strains of yeast. 



For further details on the manufacture of industrial alcohol, the 

 reader is referred to Industrial Microbiology by Prescott and Dunn.^* 



The Manufacture of Industrial Alcohol from Cellulosic Materials. 

 At least three processes have been developed in the attempt to 

 utilize cellulose from waste wood. The United States has been in 

 the fortunate position where it has not had to rely to any great 

 extent upon this raw material for the source of fermentable sugars. 



The Bergius-Rheinau process^ involves, first, the shredding and 

 drying of wood to a water content of about 0.5 per cent. The dried 

 wood is then treated with a 40 per cent solution of hydrochloric acid 

 at room temperature. The acid extract is distilled at about 36° C. 

 under vacuum to separate off most of the acid, which can then be 

 regenerated, reconcentrated, and re-used. The hydrolysate is fur- 

 ther concentrated by spray drying and the resultant particles of dried 

 material collected in a cyclone (a device which, by centrifugal force, 

 gathers small particles in air). The solid hydrolysate contains a 

 high percentage of fermentable sugar. 



