Product category:
Titration equipment
News Release from: Metrohm UK | Subject: Rancimat
Edited by the Laboratorytalk Editorial
Team on 24 February 2005
Evaluating the effects of antioxdants
Instrument provides a simple method of initially determining the stability of a new or existing antioxidant/stabiliser
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
This article was originally published on Laboratorytalk on 8 Feb 2008 at 8.00am (UK)
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Oxidative stability of biodiesel to EN 14214
The 873 Biodiesel Rancimat is a modern, PC-controlled instrument for the convenient determination of the oxidation stability of oils and fats
Rancimat method saves time evaluating antioxidants
The 743 Rancimat instrument from Metrohm UK is designed to evaluate the effects of antioxidants on edible oils and food products containing oils and fats
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 and oxygen collectors and complexing agents which considerably improve the stability of a foodstuff.
Further reading
Application monographs on edible oils analysis
The Rancimat method is considerably less costly, less labour-intensive but as accurate as the traditional active oxygen method (AOM) for the oxidation stability index (OSI) of natural fats and oils
Oxidative stability of diesel and biodiesel
The Metrohm 873 is specifically designed to analyse the oxidative stability of biodiesel, diesel and blends
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 even extrapolate induction times for different temperatures, therefore forecasting the stability of a product at lower temperatures than experimental.
Evaluating the 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 which 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 summarize, the Rancimat can determine the effectiveness of antioxidants in fats and oils at different temperatures and without the need for any great cleaning procedures. Request a free brochure from Metrohm UK ...
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