GIFSQ Tools · Module 1 — Food Composition & Proximate Analysis · Tool 8 of 500
Record a Soxhlet fat extraction run — sample and flask weights, cycles, time and solvent — and get crude fat % plus a run-completeness check.
Try sample values — fills the form with the worked example below.
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Crude fat (%)
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Extracted fat (g)
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Fat %, dry basis
Equation: Crude fat % = (mflask+fat − mflask empty) ÷ msample × 100
Dry basis: Fat % (dry) = Fat % ÷ (1 − moisture % ÷ 100).
Method: Soxhlet ether extraction, AOAC 920.39 (crude fat in feeds) / AOAC 963.15 (fat in cocoa products); petroleum ether or diethyl ether as the solvent, extraction until the solvent in the siphon runs clear.
Assumptions: all ether-soluble material in the flask is fat; the sample is dry and finely ground; extraction ran until complete.
Limitations: the result is crude fat, not true fat — it counts pigments, waxes and other ether-soluble matter; bound lipids need acid hydrolysis first (AOAC 922.06); a short run reads low.
Rounding: results to 2 decimal places; intermediate values are not rounded. A run counts as complete at 4 or more cycles and 240 minutes or more.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Dry basis: Fat % (dry) = Fat % ÷ (1 − moisture % ÷ 100).
Method: Soxhlet ether extraction, AOAC 920.39 (crude fat in feeds) / AOAC 963.15 (fat in cocoa products); petroleum ether or diethyl ether as the solvent, extraction until the solvent in the siphon runs clear.
Assumptions: all ether-soluble material in the flask is fat; the sample is dry and finely ground; extraction ran until complete.
Limitations: the result is crude fat, not true fat — it counts pigments, waxes and other ether-soluble matter; bound lipids need acid hydrolysis first (AOAC 922.06); a short run reads low.
Rounding: results to 2 decimal places; intermediate values are not rounded. A run counts as complete at 4 or more cycles and 240 minutes or more.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: 2.000 g sample, empty flask 85.432 g, flask with fat 85.672 g, 6 cycles in 300 minutes. Extracted fat = 85.672 − 85.432 = 0.240 g; crude fat = 0.240 ÷ 2.000 × 100 = 12.00 %; run complete (6 cycles, 300 min). With moisture 10.00 %, fat on a dry basis = 12.00 ÷ 0.90 = 13.33 %.
Enter values above to see results.
Typical crude fat: wheat flour 1–2 %, oats 6–7 %, oilseeds 20–50 %. If the flask with fat weighs less than the empty flask, check the balance readings — fat cannot be negative. Tool 8 of 500 — GIFSQ
