ANKOM 2000 Series - Manual (Page 41)

Operator’s Manual
Rev E 1/14/15
pg. 41
Appendix C – Crude Fiber Method
Crude Fiber Analysis in Feeds - Filter Bag Technique (for A2000 and A2000I)
AOCS Approved Procedure Ba 6a-05
Definition
This method determines Crude Fiber which is the organic residue remaining after digesting with 0.255N H
2
SO
4
and 0.313N NaOH. The
compounds removed are predominantly protein, sugar, starch, lipids and portions of both the structural carbohydrates and lignin.
Scope
This method is applicable for all feed materials such as grains, meals, pet foods, mixed feeds, forages, and the following oilseeds: corn and
soybeans.
Apparatus
1. Analytical Balance—capable of weighing 0.1 mg.
2. Oven—capable of maintaining a temperature of 102 ± 2°C
(ANKOM
RD Dryer, ANKOM Technology).
3. Electric muffle furnace—with rheostat control and pyrometer
that will maintain a temperature of 600 ± 15°C.
4. Digestion instrument—capable of performing the digestion at
100 ± 0.5°C and maintaining a pressure of 10-25psi. The
instrument must be capable of creating a similar flow around
each sample to ensure uniformity of extraction (ANKOM
2000
with 65rpm agitation, ANKOM Technology).
5. Filter Bags—constructed from chemically inert and heat resistant
filter media, capable of being heat sealed closed and able to
retain 25 micron particles while permitting solution penetration
(F57 or F58, ANKOM Technology). See Numbered Notes 1.
6. Heat sealer—sufficient for sealing the filter bags closed to ensure
complete closure (1915, ANKOM Technology).
7. Desiccant Pouch—collapsible sealable pouch with desiccant
inside that enables the removal of air from around the filter bags
(MoistureStop weigh pouch, ANKOM Technology).
8. Marking pen—solvent and acid resistant (F08, ANKOM
Technology).
Reagents
1. Sulfuric acid solution—0.255 ± 0.005N. 1.25g H
2
SO
4
/100ml.
Concentration must be checked by titration.
CAUTION1: Sulfuric acid is a strong acid and will cause severe
burns. Protective clothing should be worn when working with
this acid. Always add acid to water and not the reverse.
2. Sodium hydroxide solution—0.3130 ± 005N. 1.25g
NaOH/100ml. Concentration must be checked by titration.
CAUTION2: Sodium hydroxide can severely burn the skin,
eyes, and respiratory tract. Protective clothing should be worn
when working with this acid. Always add caustic material to
water and not the reverse.
Sample Preparation
Grind samples in a centrifugal mill with a 2mm screen or cutter type
(Wiley) mill with a 1mm screen. Samples ground finer may have
particle loss from the filter bags and result in low values.
Crude Fiber Procedure (see the Crude Fiber Analysis section of the
Operator’s Manual for more detail)
1. Use a solvent resistant marker to label the filter bags to be
used in the analysis.
2. Weigh and record the weight of each empty filter bag (W
1
)
and zero the balance. NOTE: Do not pre-dry filter bags. Any
moisture will be accounted for by the blank bag correction.
3. Place 0.95 – 1.00g of prepared sample in up to 23 of the
bags and record the weight (W
2
) of each. Avoid placing the
sample in the upper 4mm of the bag.
4. Include at least one empty bag in the run to determine the
blank bag correction (C
1
). See Numbered Notes 2.
5. Using a heat sealer, completely seal each filter bag closed
within 4mm of the top to encapsulate the sample. NOTE:
Use sufficient heat to completely seal the filter bags and
allow enough cool time (2 sec) before removing each bag
from the heat sealer.
6. Extract fat from samples by placing all bags into a 250ml
container. Add enough petroleum ether to cover bags and
soak for 10 minutes.
CAUTION3: Petroleum ether is extremely flammable.
Avoid static electricity. A fume hood should be used at all
times when using petroleum ether.
Pour off the solvent and allow the bags to air-dry. Spread the
sample uniformly inside the filter bags by shaking and
flicking the bags to eliminate clumping.
7. Place up to 3 bags on each of eight Bag Suspender Trays
(maximum of 24 bags). Stack the trays on the center post of
the Bag Suspender with each level rotated 120 degrees in
relation to the tray below it. Place the empty 9th tray on top.
NOTE: All nine trays must be used regardless of the number
of bags being processed.
8. Verify that the hot water supply is on and the drain hose is
securely positioned in the drain.
9. Read the Temperature Controller on the right side of the
instrument. If the temperature is higher than 20°C, cool the
Vessel as follows:
a. Fill the Vessel with cold water.
b. When the Temperature Controller reads 20°C, run
the Flush Procedure to drain the water.
(Procedure continued on next page.)