Overview
ISO 15885:2002 (IDF 184:2002) specifies a standardized analytical method for the determination of the fatty acid composition of milk fat and fats extracted from dairy products by gas‑liquid chromatography (GLC / GC). The procedure converts milk fat to fatty acid methyl esters (FAME) by transesterification and separates/quantifies individual FAME using capillary GC with a flame ionization detector (FID). ISO 15885 is a joint ISO/IDF standard developed with AOAC collaboration and is intended for routine laboratory, quality control and reference analyses.
Key topics and technical requirements
- Scope & principle: Preparation of FAME from milk/dairy fats and separation by capillary GC; results expressed as mass fraction (g of individual free fatty acid per 100 g total fatty acids).
- Reagents & references: Use analytical‑grade reagents, FAME reference mixtures (C4–C22, plus oleic/linoleic/linolenic), and a reference milk fat for quantification (e.g., certified reference material).
- Apparatus: Capillary gas chromatograph with vaporizing or cold on‑column injector options, temperature‑programmable oven (up to ~260 °C), suitable polar stationary phases, and FID. High‑purity carrier gases (H2, He or N2) and low‑impurity support gases are required.
- Performance checks: System suitability using a test mix (e.g., methyl butyrate, methyl stearate, methyl oleate) to ensure baseline separation and a resolution ≥ 1.5 between methyl stearate and methyl oleate.
- Quantification: Normalization of peak areas with correction factors derived from a reference milk fat; unidentified peaks reported as “unknown” using a correction factor of 1. Results are reported to two decimal places.
- Precision: Repeatability and reproducibility limits are defined (e.g., for components >5 g/100 g: repeatability ±5% relative, reproducibility ±15% relative), based on interlaboratory studies.
Applications and users
ISO 15885 is used by:
- Dairy industry quality control and product specification labs
- National food control and regulatory laboratories
- Research institutions studying milk composition, nutrition, and lipid profiling
- Reference laboratories preparing certified materials and method validation
Practical applications include nutritional labelling, breed/feeding studies, authentication of milk and dairy fats, and routine monitoring of fatty acid profiles in milk, butter, cheese and other dairy products.
Related standards
- ISO 15884 / IDF 182 - Milk fat: Preparation of fatty acid methyl esters (transmethylation)
- ISO 14156 / IDF 172 - Extraction methods for lipids from milk and milk products
- ISO 707 - Sampling of milk (recommended sampling)
- ISO 5725 - Precision of measurement methods (interlaboratory testing)
Keywords: ISO 15885, milk fat analysis, fatty acid composition, gas‑liquid chromatography, FAME, GC‑FID, dairy laboratory standard, milk fatty acids.
Open preview (PDF)Milk fat — Determination of the fatty acid composition by gas-liquid chromatography