ISO 661:2003 PDF

Overview

ISO 661:2003 - "Animal and vegetable fats and oils - Preparation of test sample" specifies standardized procedures for preparing a test sample from a laboratory sample of animal and vegetable fats and oils for subsequent analytical testing. The standard defines how to homogenize, heat, filter and, where necessary, dry samples prior to determinations. It expressly excludes emulsified products such as butter, margarine or mayonnaise.

Key topics and technical requirements

• Principle: Homogenization of the fat or oil; heating when necessary; filtration to remove insoluble material; removal of water by drying with anhydrous sodium sulfate.
• Homogenization: Agitation of closed containers to ensure a representative, uniform sample; special procedures for fluid clear, fluid turbid (with sediments) and semi-solid/concrete samples.
• Heating and filtration: Use of a temperature-controlled oven or a heated filtration funnel to melt or clarify samples. Avoid excessive residence time at elevated temperature to prevent oxidation or polymerization.
• Drying reagent: Use of anhydrous sodium sulfate (1–2 g per 10 g fat) to remove residual water. Note that sodium sulfate loses dehydrating effectiveness above 32.4 °C; drying temperatures must never exceed 50 °C unless samples are dissolved in solvent or dried under vacuum.
• Apparatus: Electric thermostatically controlled oven and a heated filtration funnel are specified.
• Precautions: Minimize exposure to air (preferably dry under nitrogen), control drying temperature, and ensure the filtrate is perfectly clear before analysis.

Applications

ISO 661 provides the sample preparation foundation for many analytical methods applied to fats and oils, including but not limited to moisture/volatile content, insoluble impurities, density, iodine value and other compositional tests (where heating or filtration could affect results). Proper sample preparation ensures reproducible, accurate results across laboratories and analytical techniques.

Who uses this standard

• Food testing and quality-control laboratories
• Oilseed and vegetable oil producers
• Animal fat processors and rendering facilities
• Analytical chemists performing compositional or physical property testing
• Regulatory and certification bodies assessing fat/oil quality

Related standards

Refer to other ISO methods and analytical standards that define the actual measurement procedures (e.g., moisture determination, iodine value, acidity). ISO 661 is a preparatory standard intended to be used in conjunction with the specific analytical test methods.

Keywords: ISO 661, preparation of test sample, animal and vegetable fats and oils, sample preparation, anhydrous sodium sulfate, filtration, drying, homogenization, analytical testing.