Overview
ISO 14156:2025 (IDF 172:2025) specifies validated extraction and separation methods to obtain a representative fraction of fat - including lipids and liposoluble compounds - from milk and milk products. The standard supports reliable laboratory determination of fat content and composition by defining principles, required reagents and apparatus, sample preparation, and procedural safeguards. Note: free fatty acids are excluded from the extracted fat as described in these methods.
Key Topics
- Principle: Extraction or physical separation of the lipid fraction from diverse dairy matrices (liquid milks, cream, butter, condensed and dried products, cheese) using solvent extraction or mechanical separation where appropriate.
- Reagents: Analytical-grade solvents and reagents cited include ethanol, ammonia solution, diethyl ether, n-pentane, and anhydrous sodium sulfate. The standard emphasizes reagent quality and peroxide-free solvents where required.
- Apparatus: Common laboratory equipment is specified, for example:
- Soxhlet extraction apparatus and thimbles for exhaustive extraction
- Separating funnels, water baths (various temperature ranges), rotary evaporator
- Drying oven and filtration materials
- Sample preparation: Conditioning and mixing instructions are provided for raw milk, homogenized milk, cream, evaporated and condensed milk, dried products and cheese to ensure a representative test portion.
- Procedure highlights: Typical methods combine polar and non-polar solvents, phase separations and drying steps to isolate lipids and liposoluble constituents. For matrices rich in phospholipids (e.g., buttermilk), the choice of extraction influences fatty acid composition; the standard recommends tailored steps (and salt addition) to ensure phospholipid recovery.
Applications
ISO 14156:2025 is intended for use in analytical and quality control laboratories within the dairy industry and regulatory bodies. Practical applications include:
- Routine fat determination and compositional analysis of milk and dairy products
- Preparation of lipid extracts for further analyses (e.g., fatty acid profiling, lipid class analysis)
- Method harmonization across laboratories for quality assurance and compliance with international testing protocols
- Supporting product formulation, nutritional labelling and investigational studies where representative lipid extraction is required
Benefits: standardized procedures improve comparability of results, reduce analytical variability, and support robust QC programs.
Related Standards
- ISO 12078 | IDF 159 - methods related to fat determination referenced by this document
- ISO 15884 | IDF 182; ISO 15885 | IDF 184; ISO 18252 | IDF 200 - methods for which the extraction procedures are applicable
- ISO 707 | IDF 50 - recommended sampling for milk and milk products
For implementation, laboratories should follow the reagent, apparatus and procedural guidance in ISO 14156:2025 and consult linked ISO/IDF methods for specific analytical endpoints.
