i o8 THE CARBOHYDRATES 



duct, rich in non-maltose, a fresh quantity of malt extract be 

 added, the non-maltose will be attacked and converted into 

 maltose until the amount present again attains the value 80 

 per cent, which is the normal maximum ; this experiment, 

 which is due to Brown and Morris,* shows that the non-maltose 

 is composed of different constituents, some of which are con- 

 verted into maltose by diastase more readily than others ; 

 moreover experiments have shown that these substances behave 

 differently towards yeast, some being more readily fermentable 

 than others. This non-maltose constituent represents a mix- 

 ture of the various dextrins mentioned above as having been 

 described by several authors. More recently Maquenne and 

 Roux f and others, carrying on the experiments of Brown and 

 his collaborators, have found that on prolonged action extend- 

 ing over several days, even this non-maltose is slowly attacked 

 by diastase, and a practically theoretical yield, instead of only 

 an 80 per cent yield, can be obtained. 



The action of malt on starch accordingly takes place in two 

 stages, of which the first is rapid, being completed in about 

 two hours, while the second one is very slow. According 

 to Maquenne and Roux, the first stage corresponds to the 

 hydrolysis of the amylo-cellulose (amylose) and the solution 

 of the amylo-pectin with consequent formation of dextrins ; 

 the second or slow stage consists in the hydrolysis of these 

 dextrins into maltose, and they consequently regard amylo- 

 pectin as a maltosane. 



It was mentioned above that a larger yield of non-maltose 

 is obtained at higher temperatures, and that this is regarded as 

 a mixture of dextrins, since some of it is readily converted into 

 sugar on adding more diastase, whilst some still remains which 

 resists ; this latter is most likely produced from the amylo- 

 pec.tin and corresponds to the stable dextrin described by 

 Brown and Morris, whereas the easily converted portion is 

 in all probability identical with what Brown and Morris called 

 maltodextrin or amyloin, and may have been produced by 

 a peculiar action of malt on the amylo-cellulose (amylose) 

 constituent of the starch. 



* Brown and Morris: "J. Chem. Soc., Lond.," 1885, 47, 527. 

 t Maquenne and Roux : " Compt. rend.," 1906, 142, 124, 1059. 



