AMYLODEXTUIN AND MALTODEXTRIN. 113 



can by repeated reversion and liquefaction be made to yield 102 per cent of maltose. Ordi- 

 nary starch-paste, they state, when measured by saccharifying and iodine tests, contains 

 about SO per cent of amylocellulose or artificial starch. The remaining 20 per cent of the 

 starch is composed of a mucilaginous substance which they refer to as amylopedin, to 

 which the gelatinizing property of starch they believe is due. 



Amylocellulose they describe as being partly soluble in boiling water and completely 

 soluble at 150, colored blue with iodine, devoid of gelatinizing power, and entirely 

 converted by diastase into maltose at ordinary temperatures. Amylopectin has the prop- 

 erty of gelatinization ; it does not give a blue reaction with iodine; and is not saccharified 

 by malt diastase, but merely converted into dextrins. They believe that amylopectin 

 has the property of interfering with the reversion of amylocellulose, both in the starch- 

 grain and in starch-paste. The action of liquefying diastase, they hold, is exerted upon 

 the amylopectin, and consequently that such a diastase should be named amylopedinase. 

 The saccharifying diastases, they state, act only on amylocellulose. 



In the second contribution these authors record that the conclusions formulated in 

 the previous article must be slightly modified as regards the percentage of amylocellulose, 

 and that starch-pastes in their ordinary condition contain about 90 per cent of amylo- 

 cellulose and about 10 per cent of amylopectin, unless the latter may be formed by an 

 especially active diastase with an attendant separation of a starch residue. 



Maquenne (Compt. rend., 1908, cxlvi, 317) confirmed and extended some of the 

 preceding investigations in proof of a non-colloidal or perfect solution of starch. Demineral- 

 ized starch, he states, forms absolutely limpid solutions which are not coagulated by elec- 

 trolysis, and which are transmitted by membranes and through the Chamberland filter, 

 as are salt solutions. 



Coombes (Ann. de chim. et phys., 1908, xlxxix, 280) found that natural starch con- 

 tains from 80 to 85 per cent of starch and 15 to 20 per cent of amylopectin, the latter 

 being insoluble but gelatinizable in water, not colored blue with iodine, and not at all or 

 but sUghtly saccharifiable by ordinary diastase. He believes that the group of starches 

 contain substances which do not differ in themselves, but in their degrees of condensa- 

 tion, the less concentrated being stained blue with iodine, being soluble in hot water and 

 in potassium hydrate, and being readily saccharifiable without the production of residual 

 dextrins; but, on the other hand, the most concentrated are not stained blue with iodine 

 and are resistant to the action of diastase. 



St. Jentys (Chapter II, page 58), by the agency of tannin, prepared artificial starch- 

 grains which resembled the most beautiful natural grains, such as those found in Dioscorea 

 and Carina; and by gallic acid he obtained grains resembling those of wheat, buckwheat, 

 and Chinese sokyes. 



Crystalline products which do not reduce Fehling's solution and which are formed from 

 starch by bacterial activity were examined by Schardinger (Zentralbl. f . Bakteriol., 1908, xxii, 

 98) . He found that a pure culture of Bacterium macerans gives rise to two crystalline bodies 

 which can readily be separated, owing to their marked difference in solubility in cold water. 

 The less soluble crystallized into hexagonal flakes or prismatic crystals, and gave a yellow 

 reaction with iodine. This substance he believes may be identical with Meyer's amylodex- 

 trin. The more soluble substance crystallized from alcohol in lanceolate needles. He tenta- 

 tively gave the name "crystallized amylose " to this body. The addition of iodine produced 

 gray needles which in one position appeared blue. Neither body is fermentable with yeast. 



AMYLODEXTRIN AND MALTODEXTRIN. 



The word amylodextrin, like the term soluble starch, has been used so indiscriminately 

 that it impUes no definite body, simple or compound, and hence has been the cause of 

 considerable confusion. Etymologically it signifies a body intermediate between starch 



8 



