AMYLODEXTRIN AND MALTODEXTRIN. 117 



Meyer (Die Starkekorner, loc. at., page 47) studied the microchemical bclia\ior of 

 a-amylose, /3-amylose, and amylodextrin. He prepared what he terms amylodextrin 

 from both amyloses by means of malt extract, dilute acids, and other cheinical agents. 

 He noticed that amylose in solution and in crystals, and amylodextrin, have different 

 degrees of affinity for iodine. W^ien crystallized |8-amylose (in the form of starch-grains) 

 and amylodextrin are added to a solution of amylose, and a trace of iodine is added, and 

 then gradually more and more iodine, it will be seen, he states, that the solution will be 

 colored first, then the starch-grains, and then the amylodextrin. Pure amylose solution 

 is colored a greenish-blue ^^^th a slight excess of iodine; pure amylodextrin, even in a 

 dilution of 1-6000, is colored brownish-red; a mixture of both solutions, according to the 

 relative amount of amylose, will be colored blue, blue-violet, violet, red-violet, pure red, 

 and a brownish-red. 



Billow (Archiv f. d. ges. Physiologie, 1895, Lxii, 131) obtained what he describes as 

 amylodextrin by subjecting potato starch to the action of a strong solution of potassium 

 hydroxide, heating the paste thus formed in a water-bath, diluting, neutralizing with dilute 

 acetic acid, precipitating with alcohol, dissolving in water, reprecipitating, etc. He also 

 prepared amylodextrin by means of diastase and by dilute sulphuric acid. By precipi- 

 tation with barium hydroxide he prepared several forms of amylodextrin-barium combi- 

 nations, which varied in rotatory power from 191.1° to 205.4°, and also in the percentages 

 of the amylodextrin and the barium in the combinations. 



Ost (Chem. Zeit., 1895, xix, 1501), following Lintner and Diill's methods, prepared 

 maltodextrin, but found that it had a higher specific rotatory power than that given by 

 Brown and Morris, and that the method employed by the latter investigators to determine 

 the reducing power yields fallacious results. 



Ling and Baker (Proc. Chem. Soc, 1897, clxxiii, 3) studied in detail the products 

 formed by the limited action of diastase at 70°, and they separated two unfermentable 

 substances which they prepared free from extraneous matters. These they state were 

 maltodextrin a, which is identical with the maltodextrin of Brown and Morris, but having 

 the properties (a)D = +180 and i? = 32.81; and maltodextrin /3, identical with Prior's 

 achroodextrin III (see below), and having the properties (ffl)D = +171.6 and R=43. They 

 believe that starch is broken down by diastase into a series of maltodextrins of decreasing 

 molecular weight and rotatory power, but with increasing reducing power, and which have 

 optical and reducing properties equivalent to varying mixtures of starch and maltose. 



According to Prior (Bayerisches Brauer Jour., 1896, vi, 385), the final products of 

 the action of diastase are 3 achroodextrins (I, II, and III) and maltose. Lintner's isomal- 

 tose he looks upon as being a mixture of achroodextrin and maltose. The achroodextrins 

 I and II correspond with the same dextrins of Lintner and Diill, but achroodextrin III is a 

 dextrin which he regards as immediately preceding the formation of sugar. This substance 

 he found has a specific rotatory power of (0)0 = +171 and a reducing power of 42.5 per 

 cent of maltose. The dextrins showed differences in fermentability. By the action of 

 yeast, glucose as well as maltose was formed. 



Wr6blewski (Ber. d. d. chem. Gesellsch., 1897, xxx, 2128; Chem. Zeitung, 1898, xxii, 

 375), in the report of his investigations of soluble starch, calls attention to the difference 

 between soluble starch and amylodextrin. He states that soluble starch is to be regarded 

 as the first product of the hydrolysis of natural starch; that it can be filtered through 

 porcelain; that it does not reduce Fehling's solution; that it is colored blue with iodine; 

 and that amyhxlextrin is a derivative of soluble starch and has the property of slightly 

 reducing Fehling's solution, and is colored reddish-brown with iodine. 



The constitution and oxidation products of maltodextrin were studied by Brown and 

 Millar (Proc. Chem. Soc, 1899, xv, II), who state that while considerable quantities of 

 this substance are present when the decomposition of starch has been arrested at the i)roper 



