AMYLODEXTRIN AND MALTODEXTRIN. 115 



maltodextrin, and maltose. At temperatures lower than G5° he states that starch is 

 converted into achroodextrin and maltose, but at higher temperatures erythrodextrin 

 and maltodextrin also are formed. The maltodextrin he assumes is composed of two 

 dextrin groups and one sugar group, and that it has the formula of C6H12O6. The specific 

 rotatory and reducing powers he gives as follows: (a)j = 71.6°, K23.5. Much attention 

 was later given to maltodextrin by various experimenters. 



In the preparation of soluble starch, Salomon (Jour. f. i^rakt. Chemie, 1883, xxviii, 

 82) obtained amylodextrin. This was prepared by boiling 100 grams of potato starch for 

 2}^ hours in 1 liter of water containing 5 c.c. of sulphuric acid, then neutralizing, precipi- 

 tating with alcohol, redissolving and reprecipitating, and, finally, boiling to a syi-up and 

 setting aside over night. The preparation after the boiling gave a violet reaction with 

 iodine. After standing over night there was found a precipitate in the form of fine grains, 

 which he states resemble Nageli's amylodextrin crystals. A watery solution of this deposit 

 gave a blue or a reddish-^dolet reaction with iodine, the latter coloration being attributed 

 by Salomon to an impurity in the form of dextrin. The specific rotatory power is recorded 

 as (a) J +21 1.50° -211.97°, (a)D+189.98°-190.24°. 



Meyer (Botanische Zeitung, 1886, xlix, 697, 713), in studying the nature of starch- 

 cellulose, states that amylodextrin constantly origmates during the treatment of starch- 

 paste with dilute acids, diastase, pepsin, saliva, and in general all substances which cause 

 a disaggi-egation of the starch-substance in the presence of water. But if the action of 

 the sphtting agent is very energetic from the beginning, the transformation of the amylo- 

 dextrin is so rapid that no skeletons will be formed. The skeletons, he states, consist of 

 pm-e amylodextrin only when they no longer stain violet or blue, but yellowish or reddish 

 brown when allowed to stand in iodine solution for about 5 minutes. He also noted the 

 formation of spherocrystals (occasionally of plates) which resembled starch-grains, except 

 that the interference figure in polarized light was not orthogonal but diagonal; but both 

 sahva and acid skeletons, he records, behave toward polarized light the same as intact 

 grains. The crystals and the skeletons reacted identically to various reagents, including 

 iodine, from which he concludes that they are an identical substance. Carl Nageli (loc. 

 cit.) differentiated the soluble granulose from the skeleton-Uke cellulose by subjecting raw 

 starch to the prolonged action saliva, and Walter Nageli (loc. cit.) found that as long as 

 these skeletons showed any color reaction with iodine they were converted into amylo- 

 dextrin. Griessmayer (Allgem. Bauer, und Hopfenzeit., 1887, xxvi, 147), in studying the 

 real nature of starch cellulose, recorded that the skeleton-hke substance of the grains is 

 converted by dilute acid into amylodextrin. He digested raw starch in a 12 per cent solu- 

 tion of hydi'ochloric acid for 100 days in the cold. The skeleton-like residue was washed 

 free from acid and other extraneous substances. Wlien dried it represented 30 per cent 

 of the original quantity of starch. It was almost completely soluble in hot water, and by 

 freezing spherocrystals of amylodextrin were obtained. 



Brown and Morris (Jour. Chem. Soc, 1885, xvii, 526; Aim. d. Chem. u. Pharm., 

 1885, XXIII, 72; Jour. Chem. Soc. Trans., 1889, lv, 449 and 462) devoted considerable 

 attention to maltodextrin and made, among other studies, comparative investigations 

 of amylodextrin, maltodextrin, and inulin. In their earlier contributions they disagi'ee 

 with Herzfeld (page 114) that maltodextrin is a mixture of dextrin and maltose, and 

 they hold that his so-called maltodextrin was impure. They state that a mixture of dex- 

 trin and maltose prepared so as to have the same optical activity and reducing power as 

 maltodextrin is separable into its constituents by treatment with alcohol, whereas true 

 maltodextrin is not thus separable; from a mixture of maltose and dextrin maltose may be 

 fermented off, but not so with maltodextrin; when a mixture of dextrin and maltose is 

 subjected to malt extract a residue of dextrin is always left, while with maltodextrin there 

 is no residual dextrin; and when a mixture of dextrin and maltose is subjected to dialysis 



