How to determine iodine value of oils and fats: new method

The iodine value is an important parameter to be defined when there is a need to identify the characteristics of an oil or mixture of oils of animal or vegetable origin. As a measure of the number of unsaturation contained in fatty acids, it is used to demonstrate the purity and quality of an oil or a fat. The more iodine that reacts with the fat, the greater the presence of double bonds in the sample.

The standard method for determining the iodine number

The standard method for carrying out iodine value determination is the Wijs method. The fatty substance to be tested, dissolved in carbon tetrachloride or chloroform, is then treated with a known volume of Wijs' reagent (Iodine trichloride solution). After the established contact time has expired, the iodine excess that has not reacted with the unsaturations in the sample is titrated with a sodium thiosulphate solution. Performing this time-consuming method requires a qualified operator who is able to use the necessary equipment and knows how to handle the different reagents and solvents used. So the standard method for determining the iodine number is time-consuming and requires a qualified operator and the use of dangerous solvents.

The study

In the CDR Chemical Lab "Francesco Bonicolini" a study was carried out to validate the new CDR FoodLab® method for determining the iodine number in oils and fats.
The accuracy of the CDR FoodLab® method was evaluated by comparing its results with those obtained using the Wijs method on 14 different kinds of oils and fats. 

The results show a good correlation between the two methods, with no significant differences between them. 

Unlike the standard procedure, the CDR FoodLab® method is very simple and fast (the instrument allows analysis of the iodine value of an oil or fat in about 3 minutes). It employs photometric technology, dedicated pipettes and ready-to-use pre-filled reagents developed by the CDR research laboratories. It uses micro-quantities of sample.
It does not require the use of solvents dangerous to health, and no equipped laboratory or specialised personnel are needed.

Conclusions

The results of the study demonstrate that the new method for determining the iodine number on oils and fats implemented in the CDR FoodLab® system can successfully replace the standard method.