ANKOM XT15 Series - Manual (Page 27)

Operator’s Manual
Rev F 12/08/14
pg. 27
Appendix A – AOCS Official Fat Extraction Procedure
ANKOM Technology Method AOCS Official Procedure Am 5-04
Rapid Determination of Oil/Fat Utilizing High Temperature Solvent Extraction
Definition
This method determines crude fat by extracting with petroleum ether. The compounds extracted are predominantly triacylglycerides. Small
amounts of other lipids along with minor compounds having some solubility in petroleum ether are also extracted.
Scope
This method is applicable to solid processed foods with 0-100% fat content.
Apparatus
1. Analytical Balance—capable of weighing 0.1 mg.
2. Oven—capable of maintaining a temperature of 102 ± 2°C.
3. Extraction instrument—capable of extracting at 90 ± 2°C.
(XT10, XT15, XT20, ANKOM Technology).
4. Filter Bags—constructed from chemically inert and heat
resistant filter media, capable of being heat sealed closed and
able to retain 1 micron particles while permitting solution
penetration (XT4, ANKOM Technology).
5. Heat sealer—sufficient for sealing the filter bags closed to
ensure complete closure (1915, ANKOM Technology).
6. Desiccant Pouch—collapsible sealable pouch with desiccant
inside that enables the removal of air from around the filter bags
(MoistureStop weigh pouch, ANKOM Technology).
7. Marking pen—Solvent and acid resistant (F08, ANKOM
Technology).
8. Dryer (optional)—forced air dryer capable of maintaining a
temperature between 60-120°C (ANKOM
RD Dryer, ANKOM
Technology).
Reagents
1. Petroleum Ether (B.P. 35-65º C). Depending on the method
used, other solvents such as hexanes and ethyl ether may be
used. CAUTION: Most fat solvents are extremely flammable.
Avoid static electricity and follow safe laboratory practices
according to your local regulations when handling solvents.
Precision
Results from the collaborative study (see Table 1) indicate the
precision (S
r
, RSD
r
, r) that the analyst should use as a benchmark for
evaluation replication in the same laboratory.
Procedure (see the Fat Extraction Process section of the Operator’s
Manual for more detail)
1. Place a labeled filter bag on the balance and zero the balance.
2. Weigh 1.5 – 2g of sample into the bag and record the weight
(W
1
).
3. Heat seal the filter bag closed within 4mm of the top to
encapsulate the sample.
4. It is good practice to include a blank bag periodically,
especially when changing solvents, in order to measure any
effect on the filter bag.
5. If a meat sample has an expected fat value of > 15% or a plant
sample has an expected fat value of > 20%, then place the
filter bag with sample in a tared weigh tin (W
4
) during the
oven drying procedure in order to capture fat that may migrate
out of the bag during heating.
6. Place samples in the drying oven at 102 ± 2°C for 3 hrs (see
Numbered Note 1).
7. Cool the dried samples in the Desiccant Pouch, weigh and
record the weight (W
2
).
8. Place filter bags with sample into the bag holder and place in
the extractor.
9. Follow the extraction instrument instructions.
10. When the extraction process is complete dry the samples for
15 – 30 minutes in the oven at 102 ± 2°C or in the ANKOM RD
Dryer set at the factory setting of 110°C. (See Numbered Note
2.)
11. Cool in the Desiccant Pouch and weigh (W
3
).
Calculations
Meat samples ≤ 15% fat and plant samples ≤ 20% fat Meat samples > 15% fat and plant samples > 20% fat
% Crude Fat = 100 x (W
2
– W
3
) % Crude Fat = 100 x ((W
2
– W4) - W
3
)
W
1
W
1
Where: W
1
= Original weight of sample Where: W
4
= Weight of the weigh tin
W
2
= Weight of pre-extracted dried sample with filter
bag
W
3
= Weight of dry sample with filter bag after
extraction
NOTE: For Liquid Samples, W
2
and W
3
in the above equations will include the weight of Diatomaceous Earth (DE).