BREWING 339 



In the Scholler-Tornesch process,^^ the shredded wood, heated to 

 about 170° C, is extracted with dilute (0.4 per cent) acid under 

 pressure in contrast to the foregoing process. The wood is not dried 

 and no attempt is made to recover the acid. The dilute hydrochloric 

 acid extract is neutralized with calcium carbonate, allowed to stand 

 in a tank to permit settling, and then filtered. 



Sulphuric acid (0.5 per cent) is used in the Giordani-Leone proc- 

 ess.^® Quicklime may be used to neutralize part of the acid and the 

 rest is recovered for further use. 



The hydrolysates from the above processes are inoculated after 

 fortification with nutrients for yeast. Acetic acid, lignin, and furfural 

 are by-products of the above-described processes. 



Sulphite liquor, a waste product in the manufacture of pulp 

 from wood, has also been used in the production of alcohol ^^ (the 

 Heijkenskjold method). Calcium carbonate or lime is added to 

 raise the pH to above 5.5 and the free sulphur dioxide removed by 

 heating to 90° C. and aeration for about two hours. The waste 

 sulphite liquor is allowed to stand for some time to allow settling 

 and, after fortification with nutrients, inoculated with yeasts. 



Brewing. The production of malt beverages involves, essentially, 

 the following steps of malting, mashing, fermentation, and finishing. 



The malting step is concerned primarily with the production of 

 amylases used for the liquefaction and saccharification of the starch 

 in the grain. Selected barley is first washed and steeped in water 

 of about 10° to 15° C. The grain is then allowed to germinate for 

 a few days at a temperature of 20° to 25° C. The amylase content 

 is higher in barley after it has been sprouted. This may be due 

 either to formation of new enzymes or to the destruction of enzyme 

 inhibitors. After the germination has proceeded to a satisfactory 

 point, the malt is dried under carefully controlled conditions. 



The solubilization and digestion of the desirable portion of the 

 malt and malt adjuncts is the purpose of the mashing step. After 

 the dried and crushed grains from the malting step have been trans- 

 ferred to cookers or mash tubs, water and malt adjuncts are added. 

 The latter which may consist of corn, rice, and wheat products, and 

 sucrose or invert sugar, is often added to malt to reduce the protein 

 content of beer in the United States. The temperature of the mixture 

 is initially low, about 40° C, and is gradually increased, depending 

 upon the method used, to 60° or 70° C. The higher temperature 

 favors dextrinization whereas the lower temperature favors sacchari- 

 fication by the amylases and the digestion of proteins by the pro- 

 teolytic enzymes also present in the grain. The pH of the mixture 



