Overview
EN ISO 5537:2023 (ISO 5537:2023) is the international reference method for the determination of moisture content in dried milk and dried milk products. Published jointly by ISO and IDF and adopted by CEN, this standard specifies a gravimetric drying procedure used by laboratories and industry for accurate moisture (water) measurement in all types of powdered milk products. The moisture content is reported as a mass fraction (percentage by mass).
Key topics and technical requirements
- Scope: Applicable to all types of dried milk and dried milk products.
- Principle: A test portion is dried at 87 °C for 5 hours while a controlled flow of dry air is passed through the sample; moisture loss is determined gravimetrically.
- Test result expression: Moisture content expressed as a percentage by mass.
- Apparatus and equipment (examples specified):
- Analytical balance with mg-level readability (capable of weighing to the nearest 1 mg, readability 0.1 mg).
- Drying oven with forced ventilation, thermostatic control at 87 °C ± 1 °C.
- Oven-mounted metal block with channels for sample columns and copper tubing to supply dry air.
- Constant pressure regulator / restrictors delivering 33 ml/min ± 2 ml/min dry air per column.
- Silica gel with hygrometric indicator (dried at 150 °C for >12 h) and desiccator.
- Polypropylene columns with polyethylene filters, synthetic stoppers, PVC rod and tweezers.
- Calibrated airflow meter to verify 33 ml/min ± 2 ml/min flow.
- Procedure elements: Sampling, sample preparation, column preparation, drying under controlled airflow, mass determination and calculations.
- Precision information: The standard includes precision data (interlaboratory, repeatability, reproducibility) for various matrices.
Note: The document includes a safety warning-users must assess hazards and follow local safety regulations.
Applications and users
EN ISO 5537:2023 is intended for:
- Dairy processors and manufacturers for quality control of milk powders and instant mixes.
- Third‑party testing laboratories performing regulatory or contractual moisture analysis.
- Regulatory authorities and food inspectors for compliance and trade verification.
- R&D teams developing formulations or shelf‑life studies where accurate moisture measurement is critical.
Practical uses include process control, specification compliance, shelf-life prediction, adulteration detection and trade dispute resolution.
Related standards and context
- This edition supersedes EN ISO 5537:2004 and was prepared by ISO/TC 34 and CEN/TC 302 in collaboration with the International Dairy Federation (IDF).
- The standard is published as a joint ISO/IDF document (IDF 26:2023) and adopted by CEN as EN ISO 5537:2023.
Keywords: EN ISO 5537:2023, ISO 5537:2023, moisture content, dried milk, milk powder, reference method, drying oven, gravimetric moisture determination, dairy quality control.
