RancimatTest

The Rancimat test, also known as the Rancimat method, is an accelerated oxidation test used to evaluate the oxidative stability of fats and oils. It is widely employed in food, cosmetic, and biofuel research to compare shelf-life characteristics and to assess the impact of processing, storage, and additives. The test results are typically reported as the oxidative stability index (OSI), expressed in hours.

The test is based on a principle of accelerated aging under heat and air. A portion of the fat or oil sample is heated to a high temperature (commonly in the range of 90 to 120°C) while a constant stream of air is passed through it. Oxidation produces volatile carboxylic acids, which are carried by the air into a vessel containing water. The carried acids increase the conductivity of the distilled water; the OSI is defined as the time until a rapid rise in conductivity is detected by the instrument’s sensors.

Procedure and interpretation are standardized to ensure reproducibility. A predefined mass of sample is placed in the reaction vessel, the system is heated, and a steady air flow is maintained. Conductivity changes are recorded automatically, and the OSI is reported by the instrument’s software. Higher OSI values indicate greater oxidative stability under the chosen test conditions.

Advantages of the Rancimat test include speed, reproducibility, and its ability to compare antioxidants and processing effects. Limitations include dependence on temperature and air flow settings, potential divergence from real-world storage conditions, and the need for specialized equipment.