Overview
ISO 15884:2002 (IDF 182:2002) specifies a validated laboratory method for the preparation of fatty acid methyl esters (FAMEs) from milk fat and fats extracted from dairy products. The prepared methyl esters are intended for subsequent analysis (for example, gas‑liquid chromatography) to determine fatty acid composition. The standard excludes partially lipolysed milk fat (fat acidity > 1 mmol free fatty acids/100 g); for those samples an alternative acid‑catalysed procedure is provided in Annex A.
Key Topics
- Scope and limitations
- Applicable to milk fat and fat from dairy products.
- Not suitable for partially hydrolysed milk fat (fat acidity > 1 mmol/100 g) - use Annex A.
- Principle
- Base‑catalysed methanolysis (transesterification) of glycerides in a predominantly non‑alcoholic solution, followed by neutralization to prevent saponification.
- Required reagents
- Solvents: n‑pentane, n‑hexane or n‑heptane.
- Methanol (≤ 0.5% water), sodium hydrogen sulfate monohydrate (NaHSO4·H2O).
- Transesterification reagent: methanolic KOH or sodium methoxide (~2 mol/L). (Examples: dissolve 11.2 g KOH or 10.8 g NaOCH3 in 100 mL methanol.)
- Apparatus and conditions
- Analytical balance, vortex mixer, centrifuge (350 g ± 50 g), PTFE‑lined test tubes, pipettes.
- Typical procedure: dissolve ~100 mg fat in solvent, add 0.2 mL transesterification reagent, vortex 1 min, react 5 min, add 0.5 g NaHSO4, centrifuge 3 min; collect supernatant for GC analysis.
- Alternative (Annex A)
- Acid‑catalysed esterification with sulfuric acid in methanol for samples with high free fatty acids. Procedure uses sealed ampoules heated 3 h at 100–110 °C.
Applications
- Routine preparation of fatty acid methyl esters for:
- Fatty acid profiling by gas‑liquid chromatography (GC).
- Nutritional labeling, quality control, and product development in the dairy industry.
- Research on milk fat composition, lipidomics and dairy authentication.
- Primary users:
- Dairy and food chemistry laboratories, quality assurance teams, regulatory and research institutions performing milk fat analysis, method validation, or compositional studies.
Related Standards
- ISO 14156 / IDF 172 - Extraction methods for lipids and liposoluble compounds (sample preparation).
- ISO 15885 / IDF 184 - Determination of fatty acid composition by gas‑liquid chromatography (analysis after derivatization).
- ISO 2446 - Milk - Determination of fat content (routine method).
- ISO 707 - Guidance on sampling milk and milk products.
This standard is essential when preparing FAMEs from dairy fats reliably and reproducibly for analytical workflows in milk fat composition and quality testing.
