112 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



predcjiiiinates coagulation will not occur. Relatively high temperatures, they ascertained, 

 are favorable to the action of diastase, while low temperatures are favorable to amylo- 

 coagulase, and coagulation is favored as the temperature is lower and the duration of heating 

 shorter during the preparation of the solution of starch. With a 2 per cent solution of 

 starch, coagulation may occur at 8° but not at 20°; but with a 4 per cent solution 

 coagulation takes place readily at 15° to 25°. The proportion of coagulum formed 

 may be increased by A'arious agents, and it was raised from 14.4 to 24.1 per cent with 

 sodium hych-ate at 15°. They note here that only a part of the amylocellulose is resistive 

 to malt extract at 67°, and also that while the activity of amylocoagulase is destroyed 

 by heating in the moist condition for 5 minutes at 63°, it is not destroyed in the dry state, 

 and that it is present in kilned malts as well as in cured malts. 



During the same year two articles were published by Maquenne (Compt. rend., 1904, 

 cxxxviii, 213 and 375), in which he recorded the results of his investigations on the pro- 

 portions of amylocellulose formed from starch-solutions of different strengths. Such solu- 

 tions were prepared by gelatinization of starch in a bath of boiling water, and afterwards 

 by heating the preparation in the autoclave for 15 minutes at 120°. These solutions were 

 set aside for 4 days at 9° to gelatinize, and then were saccharified by malt extract, and 

 the results compared with those of similar solutions that were saccharified immediately 

 after being taken from the autoclave. With the reverted solutions the amount of soluble 

 matter formed was found not to increase in proportion to the amount of starch, contrary 

 to what was found in the check solutions. Maquenne regards both raw starch and reverted 

 starch as containing amylocellulose in different stages of condensation, that amylocellu- 

 loses are obtained from comminuted grains by solution in cold water, that they are there- 

 fore present in reverted starch-paste and in raw starch-paste, and that they are dissolved 

 at high temperatures and therefore not apparent in freshly prepared starch-paste. 



Further studies of the re\'ersion phenomena of soluble starch were made bj^ Roux 

 (Compt. rend., 1905, cxL, 440, 943, 1259). In the first of these articles he shows that the 

 reversed action may proceed at any temperature between 0° and 150°, but that at the 

 latter temperature the amylocellulose liquefies and then undergoes a degradation into a 

 less complex form. He made the very interesting observation that, by the incomplete 

 degradation of amylocellulose, "artificial starch-grains" can be produced which under 

 the microscope show the peculiar structure of natural starches, and he lielie\'es that both 

 natural and artificial starches are mixtures, and that they differ chemically owing to the 

 existence of forms of variable degrees of condensation of the same nucleus. 



In the second article he describes three types of artificial starch of different degrees 

 of conversion, which are completely soluble at 150°, 120° and 100°, respectively. The 

 reversion was more rapid, he noted, in the least soluble; 4.3 per cent had reverted in 1 

 hour in the preparation soluble at 150°; while in the one soluble at 100° the percentage 

 was 1.8. The rapidity of reversion was increased by the presence of acid or alkali in proper 

 proportions. The reverted product could be redissolved only at a temperature not lower 

 than the temperature at which the original starch was soluble and, since it had the same 

 properties as the latter, he holds that it represents a return to the initial state. 



In the third article Roux compares the phenomena during saccharification of artificial 

 and ordinary starches. Using maltase at a temperature of 56° for 4 hours, the apparent 

 amounts of maltose formed were on an average 97.9 and 82.3 per cent in the artificial and 

 ordinary starches, respectively. At 67° the percentages were 55.1 and 45 respectively. 

 The dextrins formed from artificial starches, unlike those from natural starches, were 

 almost completely soluble in alcohol. 



These investigations were supplemented and extended by Maquenne and Roux 

 (Compt. rend., 1905, cxl, 1303; 1906, cxlii, 124), who found that artificial starches 

 prepared by liquefaction of amylocellulose at 150° and yielding 96 to 98 per cent of maltose, 



