538 ENZYMES DECOMPOSING SACCIIA RIDES. 



which is degraded into erythrodextrin by the action of diastase. 

 Under the hydrolytic influence of malt enzyme, this product is 

 transformed into achroodextrin, which furnishes maltose and 

 Lintner's isomaltose not to be confounded with Fischer's isomal- 

 tose, which is a well-defined, synthetic, non-fermentable sugar (see 

 p. 525, vol. ii.). Varying results were obtained by other workers, 

 both earlier and later ; in fact all those who have taken up the 

 problem of the degradation of starch by diastase a question that 

 has been under discussion for more than a century have obtained 

 different results, so that in the mouth of one author, the relatively 

 established terms, amylodextrin and erythrodextrin, and more 

 especially achroodextrin I., II., III., maltodextrin, &c., meant dif- 

 ferent substances to those implied by a second or third author, 

 who believed himself to be working with the same compounds. 

 An almost irremediable confusion exists in the nomenclature of 

 these products, owing, no doubt, to the inadequate chemical 

 and physical appliances at our disposal to enable the several 

 transformation products to be isolated as well-defined individuals. 

 Perhaps the exhaustive work of MOREAU (I.) may finally clear 

 the matter up. It would take up too much space to give even a 

 brief historical review of the various hypotheses dealing with 

 the intermediate products between starch and maltose ; and we 

 must therefore be content in this paragraph to class as " dextrin " 

 all the intermediate bodies between starch and maltose that dif- 

 ferent authors have named amylo-, erythro- and achroodextrins, 

 maltodextrins and amyloins, moreover, without drawing any 

 distinction between the dextrins produced by diastase and those 

 resulting from the action of acids on starch. 



According to the views of English chemists, the amyloins efi'ect 

 the secondary fermentation of beer in the storage cask ; which 

 view is also expressed by E. K. MORITZ (I.). If low-type amyloins 

 be added to beer, the secondary fermentation assumes a more 

 turbulent aspect and the beer matures earlier. In the opinion of 

 Moritz, secondary fermentation is not effected by the true Saccharo- 

 myceies, but by the secondary-fermentation yeasts, with which 

 Brown and Morris associate wild yeasts. This view was 

 responsible for the sceptical attitude taken up in England with 

 regard to the application of the Hansen method of pure-yeast 

 culture to the production of top-fermentation beers. According 

 to Moritz, the higher-grade amyloins, which dextrins approximate 

 more closely in composition to starch, cause gradual secondary 

 fermentation, so that the beer takes longer to mature. 



MEDICUS and IMMERHEISER (I.) were led into quite a different 

 sphere of labour on the fermentability of dextrins, by the 

 examination of a suspected wine for the presence of added 

 impure starch sugar. In their experiments on the fermentation 

 of dextrin by yeasts they employed, in part, impure starch sugar, 

 and in part prepared from this latter a so-called dextrin, which 



