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(Applicable for the determination of dietary starch in forages,
grains, grain by-products, dry, semi-moist, and moist pet food
products, and mixed feeds that range in concentration from 1 to
100%.)
Caution:
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,W FDQ FDXVH VHYHUH VNLQ EXUQV DQG H\H GDPDJH DQG LV
WR[LF LI LQKDOHG $YRLG EUHDWKLQJ IXPHV :HDU SURWHFWLYH
JORYHV FORWKLQJ DQG H\H DQG IDFH SURWHFWLRQ
Į $P\ODVH DQGJOXFRVH R[LGDVH DUH UHVSLUDWRU\ VHQVLWL]HUV
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breathing dust. Amylase preparations can cause allergic
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aerosols or dusts.
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protection.
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damage. It is suspected of causing genetic defects and
may cause damage to organs. Do not breathe dust or
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and face protection.
See
Table
2014.10
for results of the interlaboratory study
supporting acceptance of the method.
A. Principle
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DUH PL[HG ZLWK DFHWLF DFLG EXIIHU DQG KHDW VWDEOH Į DP\ODVH DQG
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is added and the test mixture is incubated for 2 h at 50°C. The
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detected in the resulting test solution using a colorimetric glucose
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to glucose. Free glucose is measured simultaneously or in a separate
analytical run for each test sample by carrying a second test portion
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incubating at 100°C for 1 h with periodic mixing. Dietary starch
is determined as 0.9 times the difference of glucose in the digested
test portion minus free glucose in the undigested test portion.
B. Apparatus
(
a
)
Grinding mill
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with a 1.0 to 0.5 mm screen, or a cutting mill with 0.5 mm screen,
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screen.
(
b
)
Homogenizer, blender, or mixer
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food, and other materials containing less than 85% dry matter.
(
c
)
Bench centrifuge or microcentrifuge.
—Capable of
centrifuging at 1000 ×
g
to 10000 ×
g
.
(
d
)
Water bath.
—Capable of maintaining 50 ± 1°C.
(
e
)
Vortex mixer.
(
f
)
pH meter.
(
g
)
Stop clock timer (digital).
(
h
)
Top-loading balance
.—Capable of weighing accurately to
±0.01 g.
(
i
)
Analytical balance.
—Capable of weighing accurately to
±0.0001 g.
(
j
)
Laboratory ovens.
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maintaining 100 ± 1°C for carrying out incubations.
(
k
)
Spectrophotometer
.—Capable of operating at absorbances
of 505 nm.
(
l
)
Pipets.
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DQG
P/ ZLWK
disposable tips.
(
m
)
Positive-displacement repeating pipet.
—Capable of
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DQG P/
(
n
)
Dispenser.
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DFFXUDWHO\ GHOLYHULQJ DQG P/
(
o
)
Glass test tubes
.—16 × 100 mm.
(
p
)
Glass tubes.
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(
q
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(
r
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Magnetic stir plate.
(
s
)
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Material
No. of labs
Mean, %
s
r
s
R
RSD
r,
% RSD
R,
% r
a
R
b
Moist canned dog food
11
1.54
0.03
0.09
2.21
5.99
0.10
0.26
Low starch horse feed
13
7.02
0.23
0.36
3.32
5.19
0.65
1.02
Dry ground corn
12
69.60
0.86
2.69
1.23
3.87
2.40
7.54
Complete dairy feed
12
28.10
0.37
1.24
1.30
4.42
1.02
3.48
Soybean meal
12
1.00
0.05
0.11
4.97
11.16
0.14
0.31
Distillers grains
13
4.11
0.11
0.20
2.67
4.94
0.31
0.57
Pelleted poultry feed
13
28.24
0.73
1.34
2.58
4.76
2.04
3.76
Corn silage
13
39.04
0.80
1.88
2.05
4.82
2.24
5.27
Dog kibble, dry
12
26.88
1.56
1.59
5.82
5.92
4.38
4.46
Alfalfa pellets
13
1.38
0.12
0.13
8.61
9.69
0.33
0.38
a
r = 2.8 × s
r.
b
R = 2.8 × s
R
.