GIFSQ Tools · Module 1 — Food Composition & Proximate Analysis · Tool 7 of 500
Solvent extraction pulls the fat out of a food sample. Weigh the flask empty and with the fat, or enter the fat weight directly — and add the dry matter % if you want the fat on a dry basis.
Try sample values — fills the form with the worked example below.
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Crude fat (%)
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Fat weight (g)
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Fat %, dry basis
Equation: Crude fat % = mfat ÷ msample × 100
From flask weights: mfat = (flask + fat) − empty flask.
Dry basis: Fat % (dry) = Fat % ÷ (dry matter % ÷ 100).
Method: Soxhlet solvent extraction, AOAC 920.39 (crude fat in animal feed) / AOAC 963.15 (fat in cacao), petroleum ether or hexane.
Assumptions: all extracted material is fat; extraction is complete; the flask is at constant weight before and after extraction.
Limitations: crude fat overstates true fat — waxes, pigments and sterols co-extract with the solvent; bound lipids in processed foods need acid hydrolysis first (Weibull-Stoldt), or Soxhlet alone understates fat; the result says nothing about which fatty acids are present.
Rounding: results to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
From flask weights: mfat = (flask + fat) − empty flask.
Dry basis: Fat % (dry) = Fat % ÷ (dry matter % ÷ 100).
Method: Soxhlet solvent extraction, AOAC 920.39 (crude fat in animal feed) / AOAC 963.15 (fat in cacao), petroleum ether or hexane.
Assumptions: all extracted material is fat; extraction is complete; the flask is at constant weight before and after extraction.
Limitations: crude fat overstates true fat — waxes, pigments and sterols co-extract with the solvent; bound lipids in processed foods need acid hydrolysis first (Weibull-Stoldt), or Soxhlet alone understates fat; the result says nothing about which fatty acids are present.
Rounding: results to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: sample 5.000 g, empty flask 120.000 g, flask + fat 120.185 g. Fat = 120.185 − 120.000 = 0.185 g; crude fat = 0.185 ÷ 5.000 × 100 = 3.70 %. With dry matter 87.00 %, fat on a dry basis = 3.70 ÷ 0.87 = 4.25 %.
Enter values above to see results.
Typical crude fat: wheat flour 1–2 %, whole milk powder 26–28 %, beef mince 10–20 %, peanuts 45–50 %. Report the basis with the number: 3.70 % as-is and 4.25 % dry basis are different results. Tool 7 of 500 — GIFSQ
