100 



DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



process of hydration (at least such as is conceived to occur through enzymatic action), as, 

 for instance, in the dextrinization of soluble starch at 115° in the apparent absolute absence 

 of moisture, and in the production of dextrin by torrefaction. It will be shown in later 

 pages that starch-paste may be liquefied, i.e., converted into "soluble starch," without 

 the formation of either dextrin or sugar, and that the paste may be converted into dextrin 

 and sugar without liquefaction. In other words, the weight of evidence points unquestion- 

 ably to the view of Lintner and Diill of a series of breaking-down processes, in wliich one 

 substance is formed from another, in contradiction to the theory of Musculus, which holds 

 that the starch-molecule is decomposed into dextrin-maltose molecules, each of wliich in 

 turn is subsequently hydrated and split. 



THE PROCESS IN THE CONVERSION OF ONE FORM OF DEXTRIN INTO ANOTHER AND 



INTO SUGAR. 



The higher dextrins are supposed during these decomposition processes to be con- 

 verted into lower dextrins, i.e., dextrins of less molecular weight, of higher solubility in 

 water, and of less solubility in alcohol. According to Lintner and Diill (Ber. d. d. chera. 

 Gesellsch., 1893, xxvi, 2533), starch is a union of high molecular complexes which, under the 

 influence of diastase, dilute acids, and certain other agents, is split up into high molecular 

 components. The first to be formed is amylodextrin ("soluble starch"), and then in turn 

 eryihrodexirin, achroodextrin, rnaUose, and isomcdtose, all of the stages going on consecu- 

 tively and together. Amylodextrin (C12H20O 10)54 gives a dark-blue reaction with iodine. 

 Each molecule of amylodextrin, according to them, is broken into 3 molecules of erythro- 

 dextrin, (Ci2H2oOio)i8+H20 = (Ci2H2oOio)i7.Ci2H2oOii, which gives a reddish-brown 

 reaction with iodine. Each molecule of erythrodextrin is in turn hydrated into 3 mole- 

 cules of achroodextrin (Ci2H2oOio)g+H20 = (Ci2H2oOio)5.Ci2H220h, which gives no 

 iodine reaction. The molecules of achroodextrin are converted into isomaltose according 

 to the following formula: 9 [(Ci2H220io)6.Ci2H220ii]-t-45 H2O = 54 C12H22O11 (isomal- 

 tose) = 54 maltose. They believe that both dextrin and starch consist of isomaltose groups. 

 These authors isolated the several non-saccharine bodies by stopping diastatic activity at 

 the necessary stage by boiling, and then repeatedly fractionating the product with alcohol. 

 The progress of the reactions could be followed by the changes in the color-reactions 

 with iodine. (For sugar products, see pages 129, 143, 144, 151, and 152.) 



The stages of digestion and the chief products are presented in the following schema, 

 which is closer in accord with the better in^'estigations and most recent de\clopments 

 than one based upon the assumption of a coincident hydrolysis into dextrin-maltose and 

 the splitting of these, and so on: 



Stages. 



1. Starch-erythrodex- 

 trin - achroodextrin- 

 maltose-glucose 



2. Erythrodextrin-ach- 

 roodextrin-maltose- 

 glucose 



3. Achroodextrin-malt- 

 ose-glucose 



4. Maltose-glucose 



Haw starch or starch-paste. 



Soluble starch— ► Erythrodextrin^ Achroodextrin ^-Maltose^ Glucose 



Erythrodextrin^ Achroodextrin —> Maltose ^-Glucose 



Achroodextrin -* Maltose-* Glucose 



Maltose -^ Glucose 



Reactions with iodine. 



Purple to a bluish 

 violet. 



Reddish-violet, 

 red, reddish- 

 brown, or red- 

 dish-yellow. 



No color reaction. 



No color reaction. 



In this schema it will be observed that a serial action is assumed by which one product 

 is formed after another, in contradistinction to the theory of the coincident formation 

 of dextrin and maltose and the splitting of these molecules. The different stages are char- 



