Rancimatmenetelmää

The Rancimat method is a widely used analytical technique for determining the oxidative stability of fats and oils. It measures the induction period, which is the time required for a measurable degree of oxidation to occur under accelerated conditions. This induction period is a key indicator of how well a fat or oil will resist degradation during storage and processing.

The Rancimat apparatus works by passing a stream of air through a sample of fat or oil that is heated to an elevated temperature, typically between 100 and 220 degrees Celsius. As the oil oxidizes, volatile oxidation products are formed and carried by the air stream into a conductivity cell containing distilled water. These oxidation products, such as aldehydes and carboxylic acids, react with the water, increasing its conductivity. The instrument continuously monitors this conductivity, and the induction period is determined as the point where the conductivity shows a significant and rapid increase, indicating the onset of rapid autoxidation.

The Rancimat method is valuable for various applications, including quality control of raw materials and finished products, formulation development, and research into the mechanisms of lipid oxidation. It provides a standardized and reproducible way to compare the stability of different fats and oils, helping manufacturers to select ingredients that will ensure product shelf life and sensory quality. The results are typically reported as the induction period in hours.