2l8 



OKUMURA ; CONTRIBUTIONS TO 



The retarding influence of an increased amount of sugar 

 upon the activity of the A sj>er£-tl/?is-d'ia.stase is (in analogy to 

 malt diastase) quite evident. 



In the same way an experiment with increasing quantities of 

 alcohol'" was made but even at 20^0 no such influence was 



noticed. 



Influence of Organic Acids. 



The peculiarity of the vioromi jDroccss which combines the 

 saccharification with alcoholic fermentation, and the frequent 

 stirring which the sake yeast requires, is continually attended 

 with the danger of acetic, lactic, and butyric fermentation setting 

 and leading to considerable loss. As it is well known that for 

 the most enzymes acids act noxiously, it was of some importance 

 to find out to what extent the acids formed by bacterial action 

 would interfere with the diastatic enzyme of Aspergilhis 

 Oryzae. As the noxious action of lactic acid was studied by 

 Kellner, Mori and Nagaoka,'-'^^ I tested only acetic and 

 butyric acid. I prepared an aqueous extract .of koj'i (i part 

 of water for 2 parts of kqfi) and precipitated the enzyme 

 with strong alcohol and ether. The precipitate, after washing 

 with some alcohol, was dissolved in a moderate quantity oi 

 water. lO cc. of that solution were mixed with 90 cc. of water 

 containing increasing quantities of acetic and butyric acid and 

 1.2% of starch in the form of paste. After standing for 24 hours 

 the determination of sugar formed proved a very noxious action 

 at 0.5 — i.o% of these acids. Further experiments with formic 

 and propionic acid proved for the former that o.z,% and for the 

 latter 1% produce a highly noxious effect upon the saccharifying 

 power. 



(1) Keltncr tested the influence of sodium chloride and found : 



Sodium chloride in % Reducing sugar, .-is dextrose. 



o 0.444 % 



2 0.223 



4 0.15s 

 10 o 054 



15 0.040 

 20 0.033 



(2) BiilMin Vol. I No. S- Imperial College of Agriculture, Tokio. From their 

 results we see that a proportion of about 0.05% of lactic acid had the best efiect and that 

 when the amount of acid is increased to o.\% and more, the inverting power of koji 

 extract is rapidly diminished, until at 0.6% and more it is suspended. 



