Overview
ISO 23319:2022 (IDF 250:2022) specifies a gravimetric method for the determination of fat content in cheeses, processed cheese products and in all types of caseins and caseinates. The method is based on the Schmid–Bondzynski–Ratzlaff (SBR) principle: acid digestion followed by solvent extraction and gravimetric measurement of extracted fat. It applies where lactose in the non-fat solids is below 5 % (mass fraction). Fresh cheeses containing high sugar additives (fruits, syrup, muesli) are excluded - for those products the Weibull–Berntrop method (see ISO 8262-3 | IDF 124-3) is recommended.
Key topics and technical requirements
- Scope and applicability: cheese, processed cheese (low-lactose matrix), caseins and caseinates. Not suitable for high-sugar fresh cheeses.
- Principle: digestion with hydrochloric acid, addition of ethanol, extraction with a mixed solvent (diethyl ether + light petroleum), removal of solvents by distillation/evaporation, and gravimetric determination of the petroleum-soluble fraction.
- Reagents: analytical-grade hydrochloric acid, ethanol (≥94 %), peroxide-free diethyl ether, light petroleum (30–60 °C boiling range) and mixed solvent prepared before use.
- Apparatus: Mojonnier-type fat-extraction flasks or extraction tubes, analytical balance (≥0.001 g readability), centrifuge (optional but recommended), drying oven, distillation/evaporation setup, fat-collecting vessels.
- Procedure elements: sampling (representative sample required), test portion preparation, blank tests, fat-collecting vessel preparation, solvent extraction and solvent removal, calculation and expression of results.
- Quality and validation: the document includes sections on precision, repeatability and reproducibility supported by interlaboratory tests (see annexes).
- Safety: warns about hazardous materials (acid, flammable solvents) and need for appropriate laboratory safety measures.
Applications and users
- Primary users: dairy testing laboratories, quality control teams in cheese and casein production, food safety authorities, and analytical method developers.
- Use cases: regulatory compliance, nutritional labelling (fat content), product formulation verification, incoming material testing (caseinates), and routine QC of processed cheeses.
- Benefits: established international method, traceability to ISO/IDF standards, suitable for a wide range of cheese and casein matrices (subject to lactose limit).
Related standards
- ISO 8262-3 | IDF 124-3 - for fat determination in high-sugar cheese products (Weibull–Berntrop principle)
- ISO 3889 | IDF 219 - specification for Mojonnier-type fat extraction flasks
- ISO 707 | IDF 50 - recommended sampling of milk and milk products
Keywords: ISO 23319:2022, fat content determination, gravimetric method, cheese analysis, caseins, Mojonnier, Schmid-Bondzynski-Ratzlaff, dairy laboratory, ISO/IDF standards.
Open preview (PDF)Cheese and processed cheese products, caseins and caseinates — Determination of fat content — Gravimetric method