On the Diastase of Koji. 



313 



At commencement solution gave rotation 



=24-8 div. . 



P= 



-74-0 



After 1\ hour at 15° C 



=237 „ . 



'■ P= 



:70-6 



After 201 hours at 10—12° C 



=21-0 „ . 



*• P= 



:62'6 





= 20-0 „ . 



'. p= 



:60-2 



50 cub. centims. of this mixture and 25 cub. centims. of koji were 

 heated for a further period. Corrected for koji added — 



After 1| hour at 40° C. rotation 112 divisions .*. P =50° 



After 2 hours longer at 45—50° C. 4-0 „ . • . P =17'8 



It will be seen that the action is very slow at low temperatures, and 

 even as high as 40° C. it is not very rapid ; but it becomes much more 

 so between 45° and 50° C.,'a temperature at which the Jcoji has been 

 found to be most active in converting starch. 



(2.) Action of Koji Extract upon Maltose. — The Japanese prepare a 

 kind of sweetmeat by the action of malt- extract upon steamed rice or 

 millet, and this product, called dme, from the examination of a large 

 number of specimens, was found to contain from 68 to 94 per cent, of 

 maltose.* A quantity of maltose was prepared from this according to 

 the directions given by Mr. 0'Sullivan,f but the purest product which 

 could be obtained contained sufficient impurity to reduce the specific 

 rotatory power from 150° to 144 0, 5. For the present purpose it was 

 unnecessary to use an absolutely pure specimen, so this was employed 

 without continuing the attempt to purify it completely : — 



100 cub. centims. of a solution of maltose containing 1'334 grm. of 

 solid matter, and the equivalent of 0*855 grm. glucose were mixed 

 with 100 cub. centims of koji solution containing 3 '5 72 grms. of solids 

 and 214 grms. glucose, and the mixture heated for 2-J hours to 35° to 

 40° C. The liquid after heating (deduction having been made for the 

 koji solution present) contained in 100 cub. centims. 1*374 grm. solid 

 matter and 1*348 grm. glucose. It is evident, therefore, that the 

 solution of maltose had been completely converted into glucose. 



A solution of maltose was prepared containing 2'68 grms. of solid 

 matter in 100 cub. centims., and which gave in a 200 millims. tube a 

 rotation of 32 '1 divisions, corresponding to a specific rotatory power 

 />=144°'5. 100 cub. centims. of this solution were mixed with 100 

 cub. centims. of koji extract containing 23 grms. of solid matter, and 

 giving in a 200 millims. tube an optical rotation of 10"5 scale-divisions. 

 This mixture was heated to 60° C. for 2 J hours, then cooled and 

 diluted to 250 cub. centims. at 15° C. It then contained 2*03 grms. 

 of solid matter in 100 cub. centims., and gave an optical rotation of 

 11*5 divisions. Deducting the rotation and amount of solid matter 



* " Transactions of the Asiatic Society of Japan," vol. vii, p. 313. 

 f " Journal of the Chemical Society," 1876, [ii], p. 128. 



T 2 



