Mar. 34,1933 
Determination of Starch Content 
1001 
RESULTS OBTAINED WITH CORRECTED REVISED METHOD 
Starch determinations by the new method, with the added feature of 
double alcohol precipitation, were made on a sample of linseed meal of 
known degree of purity and on mixtures of this linseed meal and known 
quantities of starch. This linseed meal (Sample 27262) was a ground 
traced cake, and, as calculated from the foreign matter in the seed before 
crushing, contained 3.3 per cent of nonflax material. Analysis showed 
it to have the following percentage composition: Moisture, 10.5; ether 
extract, 6.7; crude fiber, 7.8; crude protein, 35.8; ash, 5.1. 
The results obtained by a single 60 per cent alcohol defecation (repre¬ 
sented by S), as well as by the double precipitation on the same charges, 
are interpreted in Table II. 
Table II.— Comparison of the single and double alcohol precipitation modifications of 
the malt-diastase method for starch in linseed meal 
Material 
analyzed. 
!. 
f- 
4.J 
Z g 
flf 
•O « 
l 
3^ 
8 ? 
at*. 
II 
1! 
k I 
ll 
! 
a 
3 
•3 
o • 
^3 
8 | 
is 3 
n 
§8 
tfa 
LI 
n 
Starch by single alco¬ 
hol precipitation 
method. 
£a 
% 
I 
S 
1- 
ja S</) 
Pi 
T§ 
Starch by double al¬ 
cohol precipitation 
method 
I 
v 
Q 
Control (dextrose 
correction on 
malt infusion, 
etc). 
Gnu 
Gnu 
P.cU 
Prepared starch 
(sample 40 x 35 )... 
Linseed meal (sam¬ 
ple 37363 ). 
i-S 
87.5 
1.34 
Linseed meal and 
starch. 
Do. 
Do. 
5.65 
li'ii 
28.88 
Gnu 
a 35625 
35937 
1.82344 
x. 79844 
. 42031 
.41406 
.603x3 
. 60000 
.89531 
.87500 
1.37344 
1-37344 
Gnu 
o. 03875 
.04033 
.01003 
. 04XOX 
.03033 
• 03553 
.03056 
.0x883 
. 01433 
-00797 
.09600 
Gnu 
a 3850 
3996 
*• 8335 
1.8394 
.4506 
.4496 
.6337 
.6x88 
.9041 
.8892 
x. 3814 
1-3794 
Gm. 
P.ct . 
P.ct. 
P.cL 
Gnu 
P.ct. 
P.ct. 
P.cU 
1.3190 
1-2965 
■ 0563 
.0507 
, 3308 
, 3180 
4837 
4655 
9140 
.9140 
87.94 
86.44 
1.41 
1.27 
5-52 
5-45 
12.09 
xx. 64 
22.85 
22. 85 
87.19 
99.6 
1.34 
5.49 
li.*87 
22.85 
100.0 
97.2 
98.0 
99.9 
x. 2971 
1.3024 
.0525 
. 0516 
.2173 
.2039 
.4606 
.4472 
.8902 
.8884 
86.47 
86.83 
1.31 
1.39 
5-43 
5.10 
ix. 52 
xx. x8 
22. 25 
33 . 21 
86.65 
x. 30 
97-0 
5.27 
11.35 
22. 23 
93.3 
93.7 
97.2 
The second alcohol precipitation was not only unnecessary, but it be¬ 
came a source of error because of the increase in the value of the malt 
control. The dextrose determined on Solution 2 (A) does not represent 
adsorbed material. At least if there was any adsorption of starch con¬ 
version products, it was so slight as to be practically negligible. 
Other conditions being constant, the weight of the solute 18 adsorbed 
should be proportional to the weight 19 of the adsorbent (in this case the 
coagulum). The quantity of coagulum being constant, the weight of 
solute adsorbed should increase with the concentration of the solute. 
18 By solute in this case is meant starch conversion products (maltose and dextrine). 
19 The adsorption is proportional to the active surface area of the adsorbent. This is assumed to be 
proportional to the weight. 
27976—23-6 
