Wijs, Potassium Iodate, and AOCS Official Method to Determine the Iodine Value (IV) of Fat and Oil

Abstract

Fatty acid, present in edible oil, is a key constituent in our diet. The iodine number is a measure of the amount of unsaturated fatty acid in fat and oil. Iodine is a trace element that is required by humans for normal biological function. The iodine value (IV) of four edible oils was determined in this study: castor oil, peppermint oil, almond oil, and coconut oil. Iodine is a wonderful reagent for converting the unsaturation into the saturation of fat and oil. The purported technique offered a reliable and rapid determination of IV. The Wijs, or iodine monochloride, potassium iodate, and American Oil Chemists' Society's (AOCS) Fourier transform infrared spectroscopy (FT-IR) are all used to determine IV. Both Wijs and potassium iodate are iodometry-based titrations, whereas the AOCS method is applied through FT-IR. C=C stretching in the range of 1635.48cm-1-1652.77 cm-1, C=O band in the range of 1744.23 cm-1- 1747.49 cm-1, C-H stretching in the range of 2923.9 cm-1- 2925.85 cm-1, O-H stretching in the range of 3448 cm-1- 3472 cm-1 were observed in different dilution for identification of unsaturated fatty acid in numerous oils through FT-IR. All methods are satisfactory; meanwhile, the potassium iodate method is safer than the Wijs method experimentally and more economical than the AOCS method. IV for castor oil, peppermint oil, almond oil, and coconut oil were computed at 84.67 I2/100g,5.56 I2/100gm,99.09 I2/100gm,8.21 I2/100gm along with the deviation by three methods.