FERMENTATION OF DEXTRIN BY YEAST. 537 



also only partially fermented by yeast, rZ-fructose being liberated 

 and fermented, leaving a trisaccharide behind. Whether the 

 latter known as mannotriose can be in turn attacked by yeast, 

 has not yet been accurately determined. Emulsin, diastase, and 

 Aspergillus niger act on stachyose in the same manner as yeast 

 enzyme. Our knowledge of intimate properties of these enzymes 

 that decompose the last-named polysaccharides is practically nil ; 

 and their investigation would therefore be extremely valuable, 

 though complicated by the difficulty in the way of procuring the 

 higher polysaccharides. 



333. Fermentation of Dextrin by Yeast (Amylase). 



As long ago as 1833, BIOT and PERSOZ (I.) expressed the 

 opinion that dextrin can be fermented by yeasts ; though one of 

 them, PERSOZ (I.), in collaboration with Payen, came to the 

 conclusion, in the following year, that dextrin was unfermentable. 

 This view was shared by G. VARRY (I.), whereas BARFOED (I.) 

 arrived at the opposite result. 



In the course of their researches on the degradation of starch 

 by diastase, BROWN and MORRIS (IV.) found that dextrins are not 

 directly fermentable by yeasts, but require first to be hydrolysed. 

 Under certain conditions a few bottom yeasts, which act as the 

 cause of secondary fermentation in English top-fermentation 

 breweries, and are referred to by the authors in question as 

 Sacch. ellipticus and Sacch. Pastorianus, are capable of hydrolysing 

 dextrin, and thus afford an impetus to the direct fermentation of 

 that substance. According to E. R. MORITZ (I.), maltodextrins 

 are not fermented during primary fermentation, but constitute 

 the material for secondary fermentation. 



According to the conception of the English chemists, the 

 starch molecule is degraded, under the influence of diastase, in 

 such a manner that a series of dextrins, the so-called amyloins, are 

 formed, these constituting intermediate stages between soluble 

 starch and maltose. These amyloins, which are also occasionally 

 known as maltodextrins among German workers, are constituted 

 according to the theory of BROWN and MORRIS (Y.) in such a 

 manner that m molecules of maltose, O 12 H 23 O n , are combined with 

 n molecules of dextrin, 12 H SO O, . In the amyloins of low type, 

 resulting from the more extensive degradation of the starch, the 

 value m is far greater than the value n, the converse being the 

 case with the amyloins that approximate more closely to starch in 

 their composition. This clever hypothesis, however, failed to 

 stand further theoretical arid practical investigation ; in which 

 connection we need only mention the work of C. J. Lintner, who 

 arrived at a different result in numerous published researches. 

 In one of their experiments, LINTNER and DULL (II.) found that 

 the primary degradation-product of starch is an amylodextrin, 



