INDUSTRIAL ALCOHOL FROM STARCHY MATERIALS 337 



to 95 per cent concentration whereas the latter are generally redis- 

 tilled with new lots of beer. The "slop" (residual solids) may be 

 used for fertilizers or added to stock feeds. 



The Manufacture of Industrial Alcohol from Starchy Materials. 

 Alcohol may also be prepared from carbohydrates which are hy- 

 drolyzable to fermentable sugars. Starchy materials can be used as 

 the initial raw material. The starch in corn, wheat, and potatoes 

 may be hydrolyzed either by acid or diastase hydrolysis. The 

 starchy material is first macerated or ground. Where grain such as 

 corn is used, the oil-bearing germ must first be removed. 



When acid is used for the hydrolysis, sulphuric or hydrochloric 

 acid is added to the mash to adjust the concentration to the appro- 

 priate strength. The amount to be added depends on the grain and 

 the acid used. The mash is then subjected to steam under pressure. 

 When the hydrolysis of starch to glucose is complete, the acid is 

 neutralized with calcium carbonate, lime, or ammonium hydroxide. 

 Where the acid to be neutralized is sulphuric, and the alkali is cal- 

 cium carbonate or lime, a precipitate of calcium sulphate forms and is 

 separated from the wort by sedimentation and filtration. The mash 

 is fortified with ammonia (or ammonium salts) for the nitrogen 

 source and other substances required for the growth of yeasts before 

 use. 



Starchy raw material can also be hydrolyzed by diastase. The 

 amylase may be supplied by malt (germinating barley), by molds 

 or mold enzyme preparations, or by the naturally occurring diastase 

 where wheat is the raw material. 



Malt is freshly ground and first added to the starch material in 

 small amounts, approximately 10 per cent of the total to be used. 

 This pre-malting step liquefies the mash, thus making it easily 

 handled by pumping or blowing. The liquefied mash is then pumped 

 to cookers where it is steamed to solubilize the starch. After rapid 

 cooling (to prevent formation of non-fermentable substances from 

 grain) to a mashing temperature of 50° to 65° C, the rest of the 

 malt is added and the hydrolysis of starch takes place. The higher 

 temperatures favor dextrinization, the lower temperatures, sacchari- 

 fication. Kolachov and his associates have developed a rapid con- 

 tinuous process for the conversion of corn starch.^* 



In the Amylo process involving the use of selected molds, the grain 

 to be hydrolyzed is soaked in water for a few hours in order to soften 

 it. After the addition of more water, it is heated under pressure to 

 render the starch soluble. Either hydrochloric or sulphuric acid is 

 added to facilitate the liquefaction. The sterilized mash is cooled 



