Overview
ISO 17189:2003 (IDF 194:2003) is the reference method for the determination of fat content in butter, edible oil emulsions and spreadable fats (margarine, vegetable oil spreads, dairy and blended spreads). Published jointly by ISO and IDF (with AOAC collaboration), this standard defines the analytical principle, required reagents and apparatus, sample preparation, extraction and calculation steps used to report fat as a mass fraction (percent). It is intended for laboratories performing authoritative fat determinations for quality control, labeling and regulatory compliance.
Key topics and technical requirements
- Scope and principle: solvent extraction of fat from a defined test portion, separation of solvent/fat and aqueous phases, evaporation or distillation of solvent and gravimetric determination of extracted fat.
- Extraction solvent: petroleum ether (boiling range 30–60 °C) or n‑hexane (bp ≈ 69 °C); solvent must pass an extraction solvent blank test (residue ≤ 1.0 mg).
- Sample sizes:
- Butter and edible oil emulsions: typically 4–6 g (or 2–3 g if gravity separation is used).
- Spreadable fats: typically 1–2 g.
- Reagents and indicators: ethanol (≥94 % v/v) and optional Congo‑red solution to help visualize the solvent/aqueous interface (Congo‑red has health warnings).
- Essential apparatus: analytical balance (readability 0.1 mg), drying oven (102 °C ± 2 °C), desiccator, fat‑collecting vessels, leak‑proof centrifuge tubes, vortex mixer, centrifuge (50 g–100 g), pipettor and distillation/evaporation setup.
- Quality control: blank tests (method blank and solvent blank), preparation of fat‑collecting vessels, and procedural steps to ensure reproducible extractions.
- Safety: handling of flammable volatile solvents and hazardous reagents is highlighted; appropriate electrical and laboratory safety measures required.
- Precision and reporting: the standard includes sections on precision (interlaboratory tests, repeatability, reproducibility) and required elements of the test report.
Applications and users
- Food and dairy testing laboratories performing fat content determination for:
- Product specification and quality control (butter, margarine, spreads).
- Regulatory compliance and nutrition labeling.
- Ingredient verification in blended spreads and emulsions.
- Dairy processors, margarine and spread manufacturers for routine QC and formulation verification.
- Regulatory agencies and standards bodies using the method as a reference procedure in official control.
- Research laboratories studying fat composition and processing effects.
Related standards
- ISO 707 - recommended sampling method for milk and milk products (sampling referenced in ISO 17189).
- ISO/TC 34, SC 5 - technical committee responsible for milk and milk product methods; joint work with IDF and AOAC noted in the foreword.
Keywords: ISO 17189:2003, IDF 194:2003, fat determination, butter fat analysis, spreadable fats, margarine, petroleum ether extraction, reference method, extraction solvent blank, centrifuge method.