1004 
Journal of A gricultural Research voi. xxm, n©. x» 
malt-diastase digestion 
Cool to 50°C. or lower, add 20 cc. of the malt infusion, to controls as well 
as to charges, and place the flasks in a temperature-controlled water 
bath. Keeping the mash thoroughly mixed, gradually raise the tem¬ 
perature to 70°, taking from 20 to 30 minutes to accomplish this. Main¬ 
tain at 70° for 30 minutes, stirring the mixture from time to time. Then 
increase the temperature to 8o° and hold it there for 10 minutes. Finally 
heat to the boiling point. Keep the mixtures well stirred, as this 
amounts to a second gelatinization. 
Cool the contents of the flasks and the water bath to 55 0 C. Add 20 cc, 
of the malt extract, mix well, and hold at 55 0 for 1 hour, stirring about 
once every 10 minutes. At the termination of the digestion rapidly 
increase the temperature to above 8o°. 
DEFECATION WITH 60 PER CENT ALCOHOL 
The total volume of the hot mash should not exceed 200 cc. Transfer 
each mash to a 500 cc. volumetric flask. A little hot water may be used 
for rinsing, provided the total volume of the mixture does not exceed 
200 cc. Reserve the flask for subsequent rinsing. Measure out 316 cc. 
of 95 per cent alcohol. Add a portion, a little at a time, to the contents 
of the flask, with thorough shaking between additions. As soon as 
enough alcohol has been added to coagulate the colloidal matter, allow 
the coagulum to settle somewhat, and pour a little of the supernatant 
liquid back into the Erlenmeyer flask used in the digestion, thoroughly 
rinsing the contents into the volumetric flask. Complete the addition of 
the 316 cc. of strong alcohol, with constant mixing, avoiding any loss of 
material, and, after cooling to room temperature, adjust the volume with 
water so that the quantity of liquid is 500 cc. (Allowance is made for 
the volume occupied by the charge by adding 3 cc. of water for every 4 
gm. of charge present, after bringing the contents of the flask up to the 
300 cc. mark.) 
The starch conversion products from the original charge should be con¬ 
tained in the 500 cc. of 60 per cent alcohol. The determination may be 
interrupted at this stage for several days, if need be, but it would be 
necessary to readjust the volume of solution if there were a change in 
temperature. 
Mix thoroughly, breaking up any ropy coagulum as much as possible, 
by pouring back and forth from one large breaker to another. Filter 
through dry paper. Test the solid residue for starch, either micro¬ 
scopically or by the iodin color test, after elimination of alcohol and 
gelatinization with water. If more than the merest trace of starch is 
found, reject the entire determination. Evaporate exactly 200 cc. of the 
filtrate on a steam bath to a volume of from 15 to 20 cc., or until prac¬ 
tically all alcohol has been expelled. Do not allow the evaporation to 
proceed to dryness. 
ACID HYDROLYSIS 
Transfer the aqueous residue of starch conversion products to a 200 cc. 
volumetric flask with hot water, using a rubber policeman to recover all 
of the dextrine. Allow to cool somewhat, and complete the volume to 
200 cc. Transfer the contents to a suitable digestion flask, add 20 cc. of 
hydrochloric acid (sp. gr. 1.125), and connect the flask with a reflux con¬ 
denser. Heat in a boiling water bath for 2 y 2 hours. 
