154 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



UNUSUAL PKOUUCTS OF THE DECOMPOSITION 01< STARCH. 



The usual products of the decomposition of starch thi-ough the agency of enzymes, 

 dilute acids, bacteria, and other agents which bring about saccharification are erythro- 

 dextrin, achroodextrins, maltose, isomaltose, and glucose, which products are variable 

 quantitatively and qualitatively in relation to the conditions of experiment. The so-called 

 amylodextrins and maltodextrins we are justified, from the literature of the subject, in 

 regarding as mixtures. Such dextrins and sugars, as noted, may be looked for with cer- 

 tainty luider ordinary conditions of experiment with most digestive agents, but certain 

 unusual products may be formed under modified conditions or by certain agents. A num- 

 ber of references have been made to such products, as, for instance: To Leitner (page 127), 

 who found through the action of permanganate that gummy substances are formed wliich 

 differ from dextrins; to Zulkowsky and Franz (page 127), who found by the prolonged 

 action of high temperature with moisture that a substance is formed wliich resembles gum 

 arable; to Zulkowsky (page 127), who by using hot glycerol found erytlirodextrin, achroo- 

 dextrin, and a number of bodies of increasing solubility as the reaction proceeded; to Ost 

 (page 128), who by the use of high moist heat obtained a dextrinous product that was not 

 a true dextrin; to Roessing (page 149), who obtained from starch syrup by the action of 

 dilute hydrochloric acid at high temperatures a modified form of dextrose which he pro- 

 visionally named (^-dextrose; and to Roux (page 149), who prepared from artificial starch 

 dextrins that were almost completely soluble in alcohol. Abnormal dextrins have been 

 reported as existing in certain beers at times, and occasionally peculiar sugars or saccharine 

 bodies have been recorded. Finally, if there be present contaminating enzymes a number 

 of non-saccharine products of varied characters, ranging between sugars and COo and 

 H2O, may be formed. 



DIFFERENCES IN THE DECOMPOSITION PRODUCTS OF DIFFERENT STARCHES. 



Sufficient evidence has been presented in Chapter II and in this chapter to justify 

 the conclusion that starch is not a uniform substance, and that it exists in many isom- 

 erous forms which differ in different species, different parts of the same plant, antl even 

 in the individual matm-e grains, etc. It is therefore reasonable to suppose that the higher 

 decomposition products, especially the so-called soluble starch and the dextrins, would 

 be produced in corresponding differentiated homologous forms; in other words, that each 

 form of starch-substance would yield peculiar constitutional forms of decomposition prod- 

 ucts which would bear specific stereochemical relationships to the constitutional structures 

 of the initial substances. Evidence in support of such a conception is found, for instance, 

 in the constitutional differences of the inner and outer parts (the "granulose" and " cellu- 

 lose") of the mature starch-grain as exhibited in the changes which ensue when the grain 

 is subjected to gelatinization and pseudo-solution by heating in water, when comminuted 

 grains are macerated in water, when the grains are subjected to certain aniline dyes and 

 to digestive and various other reagents, and when normal and reverted starches are 

 digested, etc. 



Wlien raw starch is heated in water to a proper temperature in relation to the kind of 

 starch, swelling occurs, and in the course of time the grain becomes divided iiito two parts, 

 constituting an outer portion that appears in the form of a sac or capsule, and an intra- 

 capsular semifluid substance. After a time the capsule ruptures at one or more places, 

 permitting the escape of the inner substance. By continued heating for some minutes, 

 the length of time varying with the kind of starch, the sac undergoes a complete breaking 

 down. The inner, more soluble, less dense part in case of all forms of starch, which yields a 

 blue or purple or violet reaction in the normal state, yields an intense indigo-blue coloration 

 with iodine, whereas the sacs almost always become a bluish-violet to a red-violet, showing 

 of course a chemical difference between the inner and outer parts. The reaction of the inner 



