Comparative Study between Modified and Standard Wijs Method for Measurement of Iodine Value of Different Edible Vegetable Oils and Fats Using Accelerator

Abstract

In this paper, a modified method for determining the iodine value of oil and fat is reported. The method only requires adding the catalyst mercuric acetate in the process of determination without changing the operational steps of the Wijs method and compared with the standard AOAC Wijs method in which reaction of a sample with the Wijs solution is as long as 30-60 minutes. The fast determination method can make the determination reaction finished in 3 minutes. Where in mercuric acetate is directly used in the powder form. An attempt has been made to reduce the time of the Wijs method by use of mercuric acetate as a catalyst/accelerator. The iodine value of different vegetable oils such as refined palmolein oil (Rpm1, Palm gold-Active) Sesame oil (Se ,Tilsonna) ,Refined ricebran oil (Rrb,King’s), Refined sunflower oil (Rsf, Swaad), refined sunflower (Sf1) (Sweekar), refined sunflower (Sf2) (Sundrop), refined sunflower(Sf3) (Gemini) and refined groundnut (Gn) (RRprimio) were determined by regular Wijs method for 30 minutes whereas when we apply catalytic Wijs method with use of 2 mg, 5 mg and 10 mg of mercuric acetate to perform as catalyst then it is reducing the time of analysis to 3 minutes. When catalyst is used the different values obtained for coefficient of variations are 0.05 to 0.99 for 2mg, 0.18 to 1.35 for 5mg and 0.17 to 0.8 for 10 mg whereas 0.07 to 0.82 for non- catalyst addition. The results obtained in this present work are more % difference in IV of refined groundnut oil (Rgn).