Overview
ISO 19660:2018 (IDF 237:2018) - "Cream - Determination of fat content - Acido-butyrometric method" specifies a laboratory procedure to determine the fat content of cream using the acido-butyrometric method. Intended as an analytical alternative to the gravimetric reference (ISO 2450 | IDF 16), this method applies to creams with 20–50% fat (inclusive) such as creams intended for butter manufacture, sweet/unmatured, non-inoculated, raw or heat-treated, non-homogenized, and with or without certain preservatives.
Key technical topics and requirements
- Principle: Proteins are dissolved with concentrated sulfuric acid, fat separation is aided by amyl alcohol, and the fat column is read directly on a calibrated butyrometer after centrifugation.
- Reagents: Analytical-grade reagents required, notably concentrated sulfuric acid (ρ ≈ 1.820 g/ml) and high‑purity amyl alcohol (specified composition and density ≈ 0.813 g/ml).
- Apparatus: Typical equipment includes an analytical balance (±1 mg), a cream butyrometer (0–50 % scale), pipettes/syringes, precision dispensing for acid/alcohol, centrifuge capable of ~350 g (±50 g) at the butyrometer tip, and water baths (40 °C ±2 °C and 65 °C ±2 °C).
- Procedure highlights:
- Test portion: 5.000 g sample, 10.0 ml sulfuric acid, 1.00 ml amyl alcohol; adjust to volume mark and stopper.
- Dissolve proteins by shaking and heating briefly, centrifuge (5 min), equilibrate in a water bath, and read the fat column quickly (within 10 s) to avoid error.
- Accuracy & reporting: The standard defines methods of calculation, precision (repeatability and reproducibility), required test-report content, and normative annexes for butyrometer, weighing system and stoppers.
Practical applications
- Routine quality control and compositional testing in dairy processing (cream and butter manufacture).
- Regulatory and trade testing where a standardized acido-butyrometric result equivalent to the gravimetric reference is required.
- Method validation, laboratory accreditation, and inter-laboratory comparisons for cream fat determination.
Who should use this standard
- Dairy laboratories and QC teams in cream and butter production.
- Food testing laboratories and contract analytical services.
- Standards bodies, regulators, and auditors involved in dairy product compliance.
Related standards
- ISO 2450 | IDF 16 - Gravimetric reference method (ammoniacal ether extraction) for fat in cream.
- ISO 707 | IDF 50 - Recommended sampling for milk and milk products (sampling guidance referenced in ISO 19660).
Keywords: ISO 19660:2018, acido-butyrometric method, cream fat content, butyrometer, dairy testing, cream analysis, sulfuric acid, amyl alcohol, centrifuge.
