Overview
ISO 14156:2001 - "Milk and milk products - Extraction methods for lipids and liposoluble compounds" defines standardized procedures to extract or separate a representative portion of fat (lipids and liposoluble compounds) from milk and dairy products. The standard is intended primarily as a sample pretreatment step for subsequent analyses (for example ISO 15884 and ISO 15885). It clarifies scope (solvent extraction or physical separation), notes that free fatty acids are not included in the extracted fat, and describes safety and reporting expectations.
Key topics and requirements
- Scope and principle: Extraction or physical separation of lipid fractions for later analysis; solvent extraction for most products, physical separation for high-fat products (butter, butteroil).
- Reagents and solvents: Analytical-grade reagents such as ethanol, diethyl ether, n‑pentane, ammoniacal solution and sodium sulfate are specified for extraction and drying.
- Apparatus: Typical laboratory equipment named includes Soxhlet extractor (for solid/semi-solid samples), separatory (decanter) funnel, rotary evaporator, ovens and controlled water baths.
- Sample preparation: Detailed temperature and handling procedures for different matrices:
- Milk and cream: warming, mixing and controlled cooling;
- Concentrated and sweetened milks: dilution to defined fat content before extraction;
- Dried products: reconstitution and heating;
- Cheese: grating, mixing with sand and sodium sulfate and Soxhlet extraction (example: 6 h reflux extraction).
- Solvent removal and residues: Use of rotary evaporation and optional oven drying to constant mass; caution that heating to 102 °C can decompose some fatty compounds.
- Reporting: Results must include sample identification, sampling method (if known), reference to ISO 14156:2001, operational details and any incidents affecting results.
Applications
- Routine fat and lipid composition sample preparation in dairy testing laboratories.
- Pre‑treatment for fatty acid analysis (GC or LC) using ISO 15884/15885.
- Quality control in dairy processing (milk, cream, condensed milk, butter, cheese, dried milk).
- Research on liposoluble contaminants, nutritional lipid profiling, and product development.
Who uses this standard
- Dairy analytical and quality control laboratories
- Regulatory and food safety authorities
- Food chemists and researchers working on milk lipid composition
- Standardization bodies and method validation teams
Related standards
- ISO 15884 - Preparation of methyl esters of fatty acids (related analytical step)
- ISO 15885 - Determination of fatty acid composition by chromatography
- ISO 707 - Sampling guidelines for milk and milk products
Keywords: ISO 14156:2001, milk and milk products, extraction methods, lipids, liposoluble compounds, solvent extraction, Soxhlet, rotary evaporator, dairy laboratory, fat determination, ISO 15884, ISO 15885.
