The Metrohm 743 Rancimat evaluates the effectiveness of antioxidants by measuring the oxidation stability in edible fats and oils.
The Rancimat software can be used to estimate the shelf life of products.
The oxidative stability of foodstuffs is of paramount importance in the food industry.
Antioxidants are used in fats and oils, and particularly for the protection of edible fats (or foodstuffs with added fats) from oxidative spoilage.
In addition, they are used for the stabilisation of foodstuffs containing oxidation-sensitive vitamins, amino acids and unsaturated fatty acids.
Important and well-known antioxidants include BHA, BHT, vitamin C and vitamin E.
Multi-functional antioxidants such as sesamin and carnosic acid are highly effective absorbers of radicals, oxygen collectors and complexing agents, which considerably improve the stability of a foodstuff.
A comprehensive knowledge of food-processing chemistry and technology is needed to understand food stability and, as an antioxidant is effective only at the surface of a finished product, addition is not always enough.
However, if the stability of a new or existing antioxidant/stabiliser needs to be investigated, the Rancimat initially provides a simple method.
The Rancimat provides a type of measuring arrangement with disposable reaction vessels and evaluation software with comprehensive database functions, which allows the handling of large amounts of samples and data.
The Rancimat works by blowing a stream of air through a heated sample whose volatile oxidation products are transferred into a conductivity-measuring vessel containing de-ionised water.
The conductivity is plotted as a function of time producing an oxidation curve whose point of inflection is known as the induction time.
Temperature extrapolation enables the user to interpolate or extrapolate induction times for different temperatures, therefore forecasting the stability of a product at lower temperatures than experimental.
Evaluating the effects of antioxidants using the Rancimat is done by first determining the induction time of the fat or oil at several different temperatures.
The antioxidant is then added in different amounts (or equal amounts of different antioxidants are added) and the measurements are repeated.
A measure of the effectiveness of the antioxidant at the corresponding temperature is then obtained as is a stability index.
The correct choice of stabiliser can then be determined, as can the stability at storage temperature by extrapolating the storage temperature along a linear regression of known induction times.
Therefore, the Rancimat can replace storage tests that may be prolonged.
The 743 Rancimat has two separately temperature-controlled heating blocks, each with up to four reaction vessels.
Up to four instruments can be run by a single PC, which means it is possible to run 32 samples at eight different temperatures in parallel.
A GLP set allows qualification of the measuring system.
To summarise, the Rancimat can determine the effectiveness of antioxidants in fats and oils at different temperatures and without the need for any cleaning procedures.
