Overview
ISO 3727-3:2003 (IDF 80-3:2003) specifies the standard method for calculating the fat content of butter. Rather than measuring fat directly, the standard defines a calculation that uses results from the reference determinations of moisture and non‑fat solids (performed under ISO 3727-1 and ISO 3727-2). The fat content is reported as a mass fraction (percent) and expressed to two decimal places.
Key topics and requirements
- Scope: Calculation-only method for butter fat content based on moisture and non‑fat solids analyses.
- Normative references: Relies on ISO 3727-1 (moisture determination) and ISO 3727-2 (non‑fat solids determination). These referenced methods are indispensable for correct application.
- Calculation principle: Fat content (w_f) is calculated by subtracting measured moisture (w_m) and non‑fat solids (w_nf) from 100%:
- w_f = 100% − (w_m + w_nf)
- Expression of results: Report fat content to two decimal places.
- Precision:
- Repeatability requirements are covered by the referenced ISO 3727-1 and -2 methods; duplicate determinations must meet those repeatability criteria.
- Reproducibility: in interlaboratory conditions, the absolute difference between two single results will exceed 0.25% in no more than 5% of cases (i.e., 0.25% is the key reproducibility threshold).
- Test report requirements: Reports must include sample identification, methods used (reference to ISO 3727-3 and the referenced parts), any non‑standard operating details or incidents, and the final results (including repeatability checks if performed).
Applications and users
- Dairy quality control laboratories: Routine determination of butter composition for product specification and shelf‑quality monitoring.
- Regulatory bodies and inspection agencies: Verification of butter labelling and compliance with compositional standards.
- Butter manufacturers and ingredient suppliers: Production control, formulation checks and specification acceptance testing.
- Proficiency testing providers and laboratories performing method validation: Use the precision statements and reporting requirements for interlaboratory studies.
Related standards
- ISO 3727-1: Determination of moisture content (Reference method)
- ISO 3727-2: Determination of non‑fat solids content (Reference method)
- Published jointly by ISO and IDF; developed in cooperation with AOAC International.
Keywords: ISO 3727-3, IDF 80-3, butter fat content, moisture determination, non‑fat solids, butter analysis, calculation method, reproducibility, repeatability, dairy laboratory.
Open preview (PDF)Butter — Determination of moisture, non-fat solids and fat contents — Part 3: Calculation of fat content