118 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



time, its preparation in a pure state in sufficient quantities is a laborious process. Tliey give 

 it the following rotatory and reducing values : (a)D = +181°-183°, and R = 4:2 to 43; and 

 they state that it is com])letely hydrolyzed by diastase to maltose, and by acid to d-glucose. 



The relation of maltodextrin to isomaltose was studied by Pottevin (Ann. de I'lnst. 

 Pasteur, 1899, xiii, 728), who asserts that the maltodextrin of Brown and Morris is not 

 a true compound, but simply a mixture of dextrin and maltose, as previously claimed by 

 Lintner and Diill. By fractional precipitation with alcohol he split up this maltodextrin 

 fraction, and he asserts that the differences between mixtures of dextrin and maltose 

 and maltodextrin in their behavior towards diastase and alcohol, and as regards dialyza- 

 bility, are readily explained on the basis of differences in the form of the dextrin in the 

 combination. The different dextrins differed in digestibility, solubihty in alcohol and 

 dialyzability, and he found that an artificial mixture of maltose with a properly selected 

 dextrin is absolutely identical with Brown and Morris's maltodextrin, which therefore 

 he holds is a mixture and not a true compound. 



In studies of the constitution of starch and its derivatives, Syniewski (Ann. d. Chem. 

 u. Pharm., 1899, 282) states that starch as well as the products obtained from it, such as 

 the amylose of Meyer, the amylodextrin of Lintner and Diill, and the granulose of Nageli 

 and various investigators, consists of many molecules of amylogen which are joined together 

 in the form of a carbinolanhydrid union (see page 133). When amylogen is hydi'olyzed, 

 he assumes, all of the maltose molecules are split off one after another, and dextrin remains. 

 By the continued action of malt extract the dextrin is split into isomaltose and glucose, 

 and the isomaltose finally into glucose. All the products directly obtained from starch by 

 hydrolysis he designates dextrin. Those dextrins which originate from starch by carbinol- 

 hydi'olysis, and which therefore do not reduce Fehliug's solution, he terms amylodextrin. 

 The dextrin which originates from amylodextrin after the splitting off of all the maltose 

 molecules he terms grenzdexirin . All of the dextrins between amylodextrin and grenzdextrin 

 (those from which maltose may be split off) he terms maUodexlrin. The dextrins which 

 originate from grenzdextrin by the splitting off of glucose he terms glucodextrins. 



In another research, Syniewski (Ann. d. Chem. u. Pharm., 1902, cccxxiv, 201) studied 

 an iodine compound of amjdodextrin. He also made a solution of starch by heating starch- 

 paste in the autoclave at 140°, and then subjected the solution to the action of malt that 

 had previously been heated to 78° in the presence of 0.1 per cent of formaldehyde for 216 

 hours. The starch was completely converted into a body which the author terms grenz- 

 dextrin II, and which he states is identical with the maltodextrin of Brown and Morris, 

 and with the a-maltodextrin of Ling and Baker, and with the achroodextrin of Lintner. 

 By hydrolyzing gi-enzdextrin II with fresh malt extract it was split into a compound 

 corresponding to the formula C24H40O21 and having the following rotatory and reducing 

 powers: {a)o 200 = 172.17°, R=42.7. This substance he names ; -maltodextrin. This 

 r-maltodextrin is in turn resolved into maltose and dextrinose (Lintner's isomaltose). 



Hale (Amer. Jour. Science, 1902, xiii, 379) states that amiduhn seems to stand between 

 starch and erytlu-odextrin in regard to the solubility of its iodide and in the degree of 

 digestibility with saliva. 



Ling (Jour. Fed. Inst. Brewing, 1903, ix, 446) suggests that it would be well to use 

 the term maltodextrin instead of dextrin when referring to intermediate dextrinous products 

 of diastatic activity, because tliis would prevent confusion with dextrin prepared by torre- 

 faction. He refers to the fact that Brown, Morris and Millar have stated that their mal- 

 todextrin is completely converted into maltose by diastase, but he finds by subjecting 

 a-maltodextrin (having the constants {a)-D 3.93 = +180.5, and 7^3.93 = 36.7) to the action 

 of diastase that there are formed 90 per cent of maltose and 10 per cent of glucose. 



In the process of preparation of soluble starch. Ford (Jour. Soc. Chem. Ind., 1904, 

 xxiii, 414) notes that if the treatment by dilute acid be carried too far there is a very con- 



