Overview
EN ISO 1737:2008 (Evaporated milk and sweetened condensed milk - Determination of fat content - Gravimetric method) is the ISO/CEN reference method for measuring fat in all types of evaporated milk and sweetened condensed milk (liquid, sweetened and unsweetened concentrated milk). Often referred to by the Röse–Gottlieb principle, this gravimetric method describes solvent extraction, solvent removal, and mass determination to express fat content as a percentage mass fraction.
Key topics and requirements
- Scope: Reference procedure for fat content determination in evaporated and sweetened condensed milk.
- Principle: Extraction of an ammoniacal ethanolic test portion with a mixed solvent (equal volumes of diethyl ether and light petroleum or pentane), removal of solvents by distillation/evaporation, and gravimetric determination of extracted fat.
- Reagents: Analytical-grade reagents only - ammonia solution (~25% NH3), ethanol (≥94% v/v), optional Congo red indicator, diethyl ether (peroxide-free), light petroleum (30–60 °C boiling range) or pentane (b.p. ~36 °C).
- Apparatus: Analytical balance (mg readability), centrifuge compatible with fat-extraction (Mojonnier-type) flasks/tubes, volumetric glassware and fat-collecting vessels as specified.
- Procedure elements: Sampling and sample preparation (separate notes for evaporated vs sweetened condensed milk), test portion selection, blank tests, preparation of fat-collecting vessels, extraction, drying and weighing.
- Quality measures: Calculation and expression of results, precision data including repeatability, reproducibility and interlaboratory performance, and requirements for the test report.
- Safety: Emphasis on hazards of flammable volatile solvents and laboratory safety/compliance.
Applications and users
EN ISO 1737:2008 is used by:
- Dairy industry quality control laboratories for routine and confirmatory fat analysis of concentrated milk products.
- Regulatory and inspection bodies performing compliance testing and labeling verification.
- Accreditation and testing laboratories adopting a reference method for method validation, proficiency testing, and interlaboratory comparisons.
- R&D and product development teams needing accurate fat-content data for formulation and nutritional analysis.
Practical benefits include robust, repeatable fat determination suitable as a benchmark against which faster or automated methods (MIR, NMR, rapid extraction kits) can be validated.
Related standards
- ISO 3889 / IDF 219 - Specification of Mojonnier-type fat extraction flasks
- ISO 835 - Graduated pipettes
- ISO 1042 - One-mark volumetric flasks
- ISO 4788 - Graduated measuring cylinders
Keywords: EN ISO 1737:2008, evaporated milk, sweetened condensed milk, fat content, gravimetric method, Röse-Gottlieb, diethyl ether, light petroleum, pentane, dairy testing.