ISO 12078:2006

Overview

ISO 12078:2006 (IDF 159:2006) is a reference method for determining the sterol composition of anhydrous milk fat using gas‑liquid chromatography (GLC). The standard defines a validated laboratory procedure - from sample preparation through chromatographic identification and quantification - to profile cholesterol and phytosterols in dairy fats. It is suitable for assessing milk fat purity and for detecting vegetable‑fat addition (validated on samples with ~28–32% vegetable fat).

Key topics and technical requirements

• Analytical principle: Addition of an internal standard (betulin), saponification (methanolic KOH), extraction of the unsaponifiable fraction, purification by thin‑layer chromatography (TLC), conversion to silyl derivatives and analysis by capillary GLC with a flame ionization detector (FID).
• Reagents and standards: High‑purity solvents (n‑hexane, di‑isopropyl ether, diethyl ether), betulin and cholesterol standard solutions, and phytosterol standards (campesterol, stigmasterol, β‑sitosterol) for qualitative evaluation.
• Apparatus: Typical laboratory glassware, TLC plates and developing tanks, rotary evaporator, nitrogen supply, micropipettes, and a gas‑liquid chromatograph with capillary column and FID. Carrier gases of high purity (hydrogen or helium) are specified.
• Procedure highlights: Saponification, unsaponifiable extraction, TLC purification to remove impurities, derivatization to silyl ethers, retention‑time identification against standards, and quantification by internal standard response factors.
• Quality and performance: The standard includes precision data from interlaboratory testing (repeatability and reproducibility) and prescribes reporting elements for test reports.
• Safety note: Use appropriate controls for volatile, flammable solvents and laboratory safety procedures.

Practical applications

• Dairy quality control: Verify the sterol profile of anhydrous milk fat for compositional specifications.
• Adulteration and authenticity testing: Detect and quantify vegetable fat blending in milk fat by profiling phytosterols.
• Regulatory compliance and labeling: Support claims about fat origin and content for food standards and labeling.
• Research and nutritional studies: Characterize sterol composition in dairy‑fat research and product development.

Who should use this standard

• Food and dairy analytical laboratories
• Quality assurance and regulatory testing teams
• Food chemists and R&D departments in dairy and ingredient manufacturers
• Laboratories conducting authenticity/adulteration screening

Related standards

• ISO 6799 - Sterol fraction analysis by gas‑liquid chromatography
• ISO 14156 | IDF 172 - Lipid extraction methods for milk and milk products
• ISO 3696 - Water for analytical use

Keywords: ISO 12078:2006, anhydrous milk fat, sterol composition, gas‑liquid chromatography, GLC reference method, dairy analysis, phytosterols, cholesterol.