Overview - ISO 3727-2:2001 (Butter non‑fat solids reference method)
ISO 3727-2:2001 (IDF 80-2:2001) defines the reference method for determination of non‑fat solids content in butter. It is part of the ISO 3727 series covering moisture, non‑fat solids and fat contents in butter. The method is gravimetric: water is evaporated, fat is extracted with light petroleum (or pentane) and the remaining non‑fat solids are weighed. Results are reported as a mass fraction (%) to two decimal places.
Key topics and technical requirements
- Principle: evaporate water from a known mass of butter, extract fat with volatile solvent, determine residual mass (non‑fat solids).
- Reagents: light petroleum (boiling range 30–60 °C) or pentane (bp ~36 °C). Use analytical grade reagents that leave ≤1 mg residue.
- Apparatus: ventilated drying oven at 102 °C ±2 °C, analytical balance (readability 0.1 mg, weighing to 1 mg), sintered glass filter crucible (16–40 µm), drying desiccator, water/steam bath.
- Sample preparation & handling: receive sample in airtight container; store at 2–14 °C; warm (≤35 °C or 24–30 °C when fat separation is possible); homogenize without breaking emulsion; weigh ~5 g test portion.
- Procedure:
- Dry test portion at 102 °C (typically 15 h or combined water‑bath + oven alternative).
- Extract fat by repeated washes with light petroleum into a filter crucible until no visible fat remains; wash sediment and re‑dry.
- Weigh dish + residue + crucible repeatedly until mass change ≤1 mg; use lowest mass if increase observed.
- Calculation & precision: non‑fat solids calculated from mass differences and expressed to two decimals. Repeatability: differences >0.15% occur in ≤5% of cases; reproducibility: differences >0.25% occur in ≤5% of cases.
- Safety: involves volatile, flammable solvents - electrical equipment and lab practices must comply with explosion‑risk regulations.
Applications and users
- Quality control laboratories in dairy processing and butter production
- Regulatory and standards testing for compositional labelling and compliance
- Research labs studying butter composition, product development or shelf‑life
- Third‑party testing and certification bodies that require a validated reference method
Practical benefits include a standardized, traceable method for quantifying non‑fat solids in butter for product specification, labeling, process control and regulatory enforcement.
Related standards
- ISO 3727‑1: Determination of moisture content (reference method)
- ISO 3727‑3: Calculation of fat content
- ISO 707: Guidance on sampling milk and milk products
- ISO 5725‑1 / ISO 5725‑2: Precision (trueness and precision) of measurement methods
- IDF 135: Guidance on precision of analytical methods for milk products
Keywords: ISO 3727-2:2001, butter non‑fat solids determination, reference method, non‑fat solids content, light petroleum extraction, butter analysis, IDF 80-2.