On the Diastase of Koji. 



319* 



From the experiments described in an earlier part of this paper, 

 which showed that the extract of koji caused the hydration of maltose, 

 it might at once be accepted as a fact that longer digestion of the 

 starch products with the koji solution would result in the complete 

 removal of the maltose, only dextrose and dextrin remaining, the latter 

 being much more slowly hydrated than maltose. We cannot, indeed, 

 expect any indications of definite chemical reactions occurring, because 

 they would be disguised by the simultaneous hydration of the maltose 

 and dextrin. 



The following experiments illustrate the complete removal of the- 

 maltose. 20 grms. of dry starch gelatinised and 200 cub. centims. 

 of a solution of koji were diluted to one litre and heated at 40° C. 

 for six hours, then allowed to stand for twenty hours at 15° C. The 

 solution contained in 100 cub. centims. (deduction having been made 

 for the Mji used) 1*96 grm. of solid matter and 1*68 grm. of glucose r 

 and caused a rotation of 12 "8 scale-divisions. This gives a percentage 

 composition for the solid matter — 



Dextrose 85*7 per cent. 



Dextrin 14*3 



100-00 



p (observed) =79° 



P (calculated) =81° -4 



4 grms. of gelatinised starch and 96 cub. centims. of koji solution, 

 were heated to 35° C. for 3 J hours, then evaporated to about 200 cub. 

 centims., and diluted to \ litre. The composition of the starch pro- 

 ducts in solution was — 



Dextrose 86*00 per cent. 



Dextrin 14*00 



100*00 



p (observed) =85°*7 



p (calculated) =81° 



Without attaching much importance to the fact, it may be noticed 

 that in the last two experiments the molecular ratio is about six of 

 dextrose to one of dextrin ; a mixture which would give — 



Dextrose 87 per cent. 



Dextrin 13 „ 



100 



and^=79°*4. 



Having thus shown the nature of the reaction which occurs between 

 starch-paste and the diastase of koji, some experiments will next be 



