146 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



Further studies of the actions of diastase on starch were made by Ling and Baker 

 (Proc. Chem. Soc, 1897, clxxiii, 3; Jour. Chem. Soc. Trans., 1897, lxxi, 508), in wliich 

 they describe a substance isomeric with the isomaltose of Lintner. Its rotatory power was 

 ()d = +156 and the reducing power 62.5. They beheve that it might consist of a simple 

 dextrin together -with some maltose. Petit (Compt. rend., 1897, cxxv, 1899, cxxviii, 

 1176) found in experiments in which starch was subjected to a temperature of 70 with 

 1 per cent of diastase that a dextrin was formed which upon being treated with boiling 

 dilute hydrochloric acid is within 3 hours comjDletely converted into glucose, but if the 

 reaction is arrested at the end of a half hour, two osazones can be obtained by treating with 

 phenylhydrazine and sodium acetate, one being glucosazone and the other corresponding 

 to a diose, the latter being convertible into glucose by continued action. By further treat- 

 ment with 1 per cent diastase at 50 to 55, the dextrin formed yields two substances which 

 differ in rotatory and reducing powers, the proportion of one being twice that of the other. 

 Syniewski (Ber. d. d. chem. Gesellsch., 1898, xxxi, 1791), upon subjecting soluble starch 

 prepared by sodium peroxide to the action of hydrochloric acid, found a quantity of glucose 

 equivalent to 99.3 per cent of the starch, assuming, he states, that soluble starch has the 

 formula C18H32O16. With malt extract at 65 for VA hours a yield of maltose equal to 

 82.7 per cent was recorded. 



Some of the discrepancies between the sugar determinations of different observers 

 are due to a failm-e to recognize that sugars of various kinds may be present in the grains 

 or seeds or in the diastatic extracts. In 1875, Kuhnemann (Ber. d. d. chem. Gesellsch., 

 1875, VIII, 202, 387) recognized in both germinating and ungerminated barley the presence 

 of reducing sugars. He also isolated cane sugar and found that the quantity of sugar 

 increased in germinating grains. His observations have had confirmation in the records of 

 a number of investigators. O'Sullivan (Trans. Lab. Club, 1890, iii, 5) extracted barley 

 with alcohol, and also extracted raflinose, and he showed that it is probable that both ger- 

 minating and ungerminated grains may contain maltose, levulose, glucose, and saccharose. 

 Brown and Morris (Jour. Chem. Soc. Trans., 1890, lvi, 458) found that during the germi- 

 nation of barley the "secretion diastase" converts some of the starch into maltose, and 

 that maltose is converted by the epithelium into saccharose. They also showed that the 

 excised embryos placed in a solution of maltose changed maltose into cane-sugar. 



Griiss (Wochenschr. f. Brau., 1898, xiv, 81), in investigations of the sugars in barley 

 and malt, ascertained that during the early stage of germination no erosion of the starch- 

 grains occurs and that the grains are conserved for a time at the expense of stored-up sugars. 

 Reducing sugar was found to be present in the aleurone layer under the furrow of the 

 germinating grain. Cane-sugar was not found in the aleurone layer until after the begin- 

 ning of germination, when it was detected there in larger quantity than in any other part 

 of the grain. The reducing sugars in the endosperm were found to be in greatest quantity 

 in the central part, and least in the cells contiguous to the aleurone layer. Gi'iiss believes 

 that reducing sugar is converted into cane sugar in or near the aleurone cells. In another 

 investigation, Griiss (Wochenschr. f. Brauerei, 1899, xvi, 519) made studies of the actions 

 of two groups of oxidases and one group of diastases upon transitory starches. He notes 

 among other things the formation, in the presence of air, of starch from saccharose. 



Ling (Jom-. Fed. Inst. Brew., 1898, iv, 187) determined the preformed sugars of malt 

 by extraction with an alkaline solution. By treatment with phenylhydrazine he obtained 

 an osazone which was probably glucosazone, and another which he records as being prob- 

 ably a maltosazone. 



Differences in the products of the actions of acids and enzymes were pointed out by 

 Johnson (Jour. Chem. Soc. Trans., 1898, lxxiii, 490), both in regard to final and inter- 

 mediate products (see page 151). Pottevin (Compt. rend., 1898, cxxvi, 1218) treated 

 wheat starch with successive portions of malt extract until 10 per cent of the original 



