jodverdi

Jodverdi, known in English as iodine value, is a standard measure of the degree of unsaturation in fats and oils. It is defined as the amount of iodine, expressed in grams, that can be absorbed by 100 grams of fat or oil under specific conditions. A higher jodverdi indicates more double bonds in the fatty acid chains, corresponding to greater unsaturation.

The most common method to determine jodverdi is the Wijs method. In this procedure, a sample is treated with a standard solution of iodine monochloride in acetic acid (the Wijs reagent), which adds across the double bonds. After the reaction, any unreacted iodine is titrated with sodium thiosulfate, and the result is reported as grams of iodine absorbed per 100 grams of fat (g I2/100 g). The value provides a single, comparable number reflecting overall unsaturation.

Applications and interpretation: Jodverdi is widely used in the food industry for quality control and classification of fats and oils, and it is also relevant in the evaluation of drying oils used in paints and varnishes, where higher unsaturation relates to faster drying. Typical ranges vary by fat type: highly saturated fats may have values around 5–25, common vegetable oils often fall in the 80–120 range, and drying oils can exceed 130 g I2/100 g.

Limitations: The iodine value does not differentiate between mono-, di-, or polyunsaturated bonds or their positions, and certain conjugated systems can affect results. It does not measure actual oxidative stability directly, and results can be influenced by moisture or trace oxidation. Therefore jodverdi is usually considered alongside other analyses such as fatty acid composition and peroxide value.