GLUTEN. 745 



analysis. Malted barley contains not more than 1 500th of 

 its weight of diastase. The solution of diastase has no action 

 upon many vegetable principles, such as sugar, gum, albumen 

 and gluten, but has a specific action upon starch, converting 

 a solution of that substance first into dextrin, and afterwards 

 into the sugar of starch, and such is its energy that 1 part of 

 diastase will convert 2000 parts of starch into sugar. Diastase 

 acts upon gelatinous starch even at 32, but most powerfully 

 between 140 and 150. It has the remarkable property of 

 separating the envelope from the grains of starch.* 



In the ordinary process of brewing, the mashing or infusing 

 of the malt should be begun at 168 or 170, the temperature 

 at which the diastase acts more advantageously, by which the 

 starch of the grain is converted into sweet worts. The tem- 

 perature may be afterwards raised by adding water at 185 or 

 195 to the mash tun ; the saccharisation is generally completed 

 in an hour and a half at the utmost, and the sweet worts are 

 then run into a copper to be boiled and hopped, (Black on 

 Brewing). The sugar of the cooled worts is afterwards fer- 

 mented by the action of another principle yeast and converted 

 into carbonic acid and alcohol, as will afterwards appear. The 

 diastase of 1 part of malt is often made to succharise the starch 

 of 10 or 12 parts of unmalted grain, when the sweet wort is 

 to be fermented and distilled for spirits. 



Gluten. This substance remains when the starch of wheat 

 flour has been separated by pressing the dough in water till 

 the washings are no longer milky, as a grey viscid adhesive and 

 elastic substance. It is insoluble in water, but is dissolved by 

 alkalies and also by acetic acid. It contains nitrogen, and when 

 left humid in air, has a tendency to putrify ; when completely 

 dry it is hard and brittle, with some resemblance to glue. Gluten 

 forms from 19 to 24 percent of good wheaten flour. According 

 to Davy the wheat grown in the south of Europe is richer in 

 gluten than that of colder climates ; it is peculiarly suitable on 

 that account for the manufacture of macaroni, vermicelli and simi- 

 lar pastes, which are made by a kind of wire drawing. Gluten is 

 one of the most nutritive of vegetable substances ; when se- 



* The name diastase was applied to it from fttcrrq/ti, I separate, in reference to 

 its property of separating two supposed constituents of starch. 



