Overview
EN ISO 1854:2008 / ISO 1854:2008 (IDF 59:2008) specifies the reference gravimetric method for determining fat content in whey cheese. Often referred to by the Röse–Gottlieb principle, the method extracts fat from an ammoniacal–ethanolic solution using a mixed solvent of diethyl ether and light petroleum (or pentane), then removes solvents and determines the mass of extracted fat. This standard is published by CEN/ISO/IDF and is intended as a definitive laboratory method for accurate fat determination in whey cheese.
Key Topics and Requirements
- Scope & limitations
- Applies to whey cheese that dissolves completely in ammonia solution.
- Not suitable for products with significant free fatty acids or those that do not dissolve in ammonia (results may be too low).
- Principle
- Extraction of fat from an ammoniacal ethanolic test portion with diethyl ether + light petroleum; solvent removal and gravimetric determination of extracted fat.
- Reagents
- Ammonia solution (~25% NH3), ethanol (≥94% v/v), diethyl ether free from peroxides, light petroleum (30–60 °C) or pentane, Congo red indicator (optional).
- Apparatus
- Analytical balance (readability 0.1 mg), Mojonnier-type fat-extraction flasks/tubes, centrifuge (optional), standard laboratory glassware compliant with referenced ISO standards.
- Procedure & quality controls
- Test portion preparation, blank determinations, preparation of fat-collecting vessel, solvent distillation/evaporation, calculation and expression of fat as percentage mass fraction.
- Precision data provided (repeatability and reproducibility) and requirements for test reporting.
- Safety
- Use of volatile, flammable solvents (diethyl ether, pentane) requires strict laboratory safety measures.
Applications - Who Uses It
- Food testing laboratories and dairy quality control teams measuring fat content in whey cheese for:
- Product specification and labelling
- Regulatory compliance and trade disputes
- Research and product development for whey-based cheeses
- Useful for dairy technologists, analytical chemists, regulatory authorities and certification bodies requiring a reference method.
Related Standards
- ISO 8262-3 | IDF 124-3 - alternative method using the Weibull–Berntrop principle (recommended when products do not dissolve in ammonia or contain free fatty acids).
- Normative references cited within the standard: ISO 835, ISO 1042, ISO 3889 (Mojonnier flasks), ISO 4788 - relevant for laboratory glassware and apparatus.
Keywords: whey cheese, fat content, gravimetric method, Röse–Gottlieb, EN ISO 1854, IDF 59, ammonia extraction, diethyl ether, pentane, reference method.
