Overview
ISO 5534:2004 - titled Cheese and processed cheese - Determination of the total solids content (Reference method) - specifies the reference laboratory procedure for measuring the total solids (moisture-free mass fraction) of cheese and processed cheese. The standard defines sample preparation, required reagents and apparatus, the drying procedure at 102 °C, and the calculation and reporting of results. It is the authoritative method for laboratories seeking accurate and comparable total solids data for cheese products.
Key topics and technical requirements
- Scope: Reference method for total solids content of cheese and processed cheese; note that some processed cheese preparations (per FAO/WHO Code A‑8) may not be applicable.
- Principle: Weigh a prepared test portion mixed with sand, dry at 102 °C, reweigh to determine mass loss and calculate total solids as a percentage by mass.
- Reagents: Analytical grade chemicals only; 25 % dilute HCl for sand treatment (if needed); quartz or sea sand meeting particle-size and suitability tests.
- Apparatus: Analytical balance (readability 0.1 mg), forced-ventilation drying oven (102 °C ±2 °C), desiccator, flat-bottomed dishes, stirring rods, and grinders/irons for sample preparation.
- Sample preparation: Remove rind/undesired surface, grind or grate to a representative homogenous test sample; avoid moisture loss or contamination.
- Procedure highlights:
- Prepare dish with ~20 g dried sand; perform a simultaneous blank test.
- Place ~3.0 g test portion mixed thoroughly with sand; dry until constant mass (initial 3 h then 1 h cycles until change ≤2.0 mg).
- Use blank correction and prescribed formula to compute total solids; report results to two decimal places.
- Precision: Stated performance - repeatability limit: an absolute difference >0.35 % in not more than 5 % of cases; reproducibility limit: >0.55 % in not more than 5 % of cases. An interlaboratory study involving 12 labs supports these values.
Applications and users
- Quality control laboratories in dairy processing plants for routine moisture/solids monitoring.
- Regulatory and trade testing where standardized total solids values are required for labeling, specification compliance, or commercial transactions.
- Research and development for formulation, shelf‑life, and composition studies.
- Calibration and validation of rapid or automated moisture analyzers by comparison with this reference method.
Related standards
- ISO 707 - Guidance on sampling milk and milk products (recommended sampling).
- ISO 5725‑1 / ISO 5725‑2 - Accuracy, repeatability and reproducibility of measurement methods (precision evaluation).
Keywords: ISO 5534:2004, total solids, cheese testing, reference method, drying oven 102 °C, analytical balance, processed cheese, dairy quality control.