ISO 16756:2024

Overview

ISO 16756:2024 (IDF 259:2024) provides guidance for determining total fat in milk and milk‑based products using low‑resolution time‑domain nuclear magnetic resonance (TD‑NMR) with the Carr‑Purcell‑Meiboom‑Gill (CPMG) pulse sequence. The standard covers benchtop pulsed NMR instruments configured to selectively measure glycerolipids (tri-, di- and mono‑acylglycerols), producing fat values that are comparable to conventional chemical extraction methods - without the need for matrix‑specific calibrations - while meeting the precision criteria given in Clause 12.

Key applicability points:

• For milk, cream, yogurt, ice cream, processed dairy, cheese and dairy powders
• Applicable regardless of source (species or region)
• For dry samples (moisture ≤ 10 %) or liquid/wet samples that have been pre‑dried
• Not limited by sample viscosity, colour or particle size

Key Topics and Requirements

• Principle: Use of CPMG pulse sequence to isolate signals from hydrogen nuclei in liquid glycerolipids; multi‑exponential fitting yields a linear calibration against reference methods.
• Instrument characteristics: Low‑resolution pulsed TD‑NMR (benchtop) optimized for fat detection; proton‑free sample tubes and appropriate consumables.
• Sample preparation: Pre‑drying to remove appreciable water, temperature equilibration prior to measurement, and standardised sample handling.
• Factors affecting measurement: Instrument stability, magnetic field homogeneity, magnet temperature, carryover and non‑glycerolipid interferences.
• Validation and QC: Comparison with standard reference materials, system setting validation, routine stability checks, control samples and instrument diagnostics.
• Performance metrics: Limits of detection/quantification (LoD/LoQ), repeatability, intralaboratory reproducibility and accuracy as specified in Clause 12.

Applications and Who Uses It

ISO 16756:2024 is designed for laboratories and organizations involved in dairy composition analysis, including:

• Dairy industry QC/QA laboratories performing routine milk fat analysis
• Third‑party testing and regulatory labs validating product claims
• Research institutes developing or comparing rapid fat analysis methods
• Instrument manufacturers and service providers for benchtop TD‑NMR systems

Benefits:

• Rapid, non‑destructive fat determination
• Reduced need for solvent‑based extraction and matrix‑specific calibrations
• Robust across diverse dairy matrices and processing states

Related Standards

• Published jointly by ISO and the International Dairy Federation (IDF) as ISO 16756:2024 / IDF 259:2024.
• Complements conventional chemical fat extraction reference methods (used for calibration/validation comparisons).

Keywords: ISO 16756:2024, CPMG, TD‑NMR, milk fat determination, glycerolipids, low‑resolution NMR, dairy testing, benchtop NMR, milk and milk products.