ERYTHRODEXTRIN, ACHROODEXTRIN, GRENZDEXTRIN, ETC. 



125 



(1) Wlipn starch-paste is acted upon by malt extract above 40° the specific rotatory and 



reducing powers of tlie products indicate the existence of maltose and a non-reducing 

 dextrin. 



(2) If the products of transformation are fractionally precipitated by alcohol, the (-oniiiosition 



of the several fractions, as showii by the optical and reducing powers, is capable of inter- 

 pretation on the supposition that they consist of maltose and a non-reducing dextrin. 



(3) The authors look upon the foregoing as establishing a criterion of purity for any 



sejiarated portion of the transformation jiroducts, and they ascribe any apparent 

 tlepartures from this rule, as regards substances described by other investigators, 

 as due to imjiurities or to errors in determination. 



(4) The tendency of all starch transformations when subsequently acted upon by malt 



extract at 50° or 60° is rapidly to attain a state of equilibrium, which would correspond 

 to the tenth equation CioHogOn =8H20 = 8C,2HojO,,+2C,^H2oO|o, corresponding 

 to equation 8 of the series sho^vn in table 8, in which the theoretic amount of maltose 

 contained in 100 parts of dextrins is given at each stage of conversion of starch down 

 to No. 8. When all the jiroducts derived from starch are taken together, the reac- 

 tion corresponds to an optical 



activity of (a), 3.86= +162.6, Tables. 



and to A'3.s6 = 49.3, and to a 

 percentage composition of mal- 

 tose 80.9 and dextrin 19.1. 



(5) The degradation of all of the 



higher transformations down 

 to this point is due to the hy- 

 drolysis of the more complex 

 jiolymeric dextrins and malto- 

 dextrin. 



(6) The dextrin and maltodextrin can 



be submitted to solution in 

 water, to evaporation, and 

 to frequent precipitation with 

 alcohol without being hych-o- 

 lyzed. 



(7) This is proved by the fact that the transformation products after such treatment, 



when subsequently fractionated with alcohol, yield fiactions with a mean value of 

 (a)j and K, coinciding with that of the original solution and also by the No. 8 equation. 



(8) The separated dextrins have not, as stated l)y O'SuUivan, different proioerties as re- 



gards their behavior with malt extract from those they possess when in solution with 

 tiie other transformation products simultaneously with them. 



(9) It follows that it is possible, by submitting a separated dextrin or a mixture of dex- 



trins to the action of malt extract at 50° to 60°, and determining the percentage of 

 maltose they yield, to ascertain the actual or mean position of tlie tlextrin in the poly- 

 meric series — the actual position if it be homogeneous, or the average or mean posi- 

 tion if it be a mixture. 



(10) By making use of this process it is possible to ascertain by examination of residual products 



of a beer or similar liquid, after primary fermentation is concluded, the values of (a), 

 and K of the original starch-products as transformed by the mashing process. 



(11) With the exception of No. 8 they always found, on fractionating such preparations 



with alcohol, that the dextrin is not homogeneous, but belongs partly to a higher 

 and partly to a lower equation. 



(12) It follows from No. 11 that the whole of the starch-product in a transformation 



is not simultaneously affected, but that some jjortions are hydrolyzed faster than 

 others and that a sharp line can not be drawn between the equations higher than No. 8. 



(13) The preparation of absolutely non-reducing dextrins is impossible by the mere precipi- 



tation with alcohol, even when aided by fermentation, but this can be accomplished 

 by treating the dextrin with alkaline mercuric cyanide. 



(14) The dextrins are not directly fermentable by yeast, but require first to be hydrolyzed. 



(15) When the action of malt extract on starch-paste is limited there is always fountl, 



among the products of transformation, besides maltose and dextrin, a third body 

 which has optical and reducing properties corresponding to an apparent composition 

 of 34.6 per cent of maltose and 65.4 per cent of dextrin. 



