Fat Iodine Number Calculators

0 calculators tagged with “Fat Iodine Number”

Iodine value (IV), also called iodine number or iodine index, measures the degree of unsaturation of a fat or oil — the total number of carbon-carbon double bonds (C=C) present. It is defined as the grams of iodine (I₂) absorbed by 100 grams of fat. Highly unsaturated oils (flaxseed, fish oils) have high iodine values (>150); saturated fats (coconut oil, butter) have low values (<20). Iodine value is used in food science, biodiesel production, and quality control to characterize fatty acid composition and predict fat behavior in processing, storage, and industrial applications.

All Calculators

No calculators found for this topic.

Iodine Value Formula

IV = (V_blank − V_sample) × N × 12.69 / W

where V_blank and V_sample are volumes (mL) of sodium thiosulfate used in blank and sample titrations, N is the normality of thiosulfate, and W is the sample weight (g). The factor 12.69 converts milliequivalents to grams of iodine per 100 g.

Wijs Method (Standard Test)

Fat is dissolved in glacial acetic acid/cyclohexane and treated with Wijs reagent (iodine monochloride, ICl) in excess. ICl adds across double bonds (electrophilic addition). Excess unreacted Wijs reagent is back-titrated with sodium thiosulfate, with starch as indicator (blue to colorless endpoint). AOCS Official Method Cd 1d-92 is the standard protocol.

Typical Iodine Values

  • Coconut oil: 7–12
  • Palm oil: 50–55
  • Olive oil: 75–94
  • Sunflower oil: 110–145
  • Soybean oil: 120–143
  • Linseed (flaxseed) oil: 168–204
  • Fish oil: 120–180+

Applications

In food science: predicts oxidative stability — higher IV means more double bonds susceptible to oxidation and rancidity. Oils are classified as drying (IV >130, e.g., linseed), semi-drying (100–130), or non-drying (< 100). In biodiesel: IV predicts fuel oxidation stability and cold-flow properties. In quality control: monitors hydrogenation progress — IV decreases as double bonds are saturated.

Glossary

Iodine Value (IV)
Grams of iodine absorbed per 100 g of fat; measures the total C=C double bond content (degree of unsaturation); higher IV = more unsaturated fat with greater oxidation susceptibility.
Wijs Method
The standard AOCS method for measuring iodine value using iodine monochloride (ICl) reagent and back-titration with sodium thiosulfate; official method Cd 1d-92.
Drying Oil
An oil with iodine value >130 (e.g., linseed, tung oil) that polymerizes and solidifies upon exposure to oxygen; used in paints, varnishes, and linoleum.

Frequently Asked Questions

Iodine value (IV) measures the degree of unsaturation in a fat or oil — it is the grams of iodine absorbed per 100 g of fat. Each carbon-carbon double bond (C=C) in a fatty acid can react with one molecule of I₂ (or equivalent). Higher IV means more double bonds — a more unsaturated fat. Saturated fats like coconut oil have very low IV (7–12); highly unsaturated oils like linseed oil have IV of 168–204. IV is used to characterize fat composition and predict oxidative stability.

The Wijs method is the standard AOCS procedure for measuring IV. A known mass of fat is dissolved in solvent and treated with excess Wijs reagent (iodine monochloride, ICl). ICl adds across all C=C double bonds. Unreacted excess ICl is converted to I₂ by adding potassium iodide, then the I₂ is titrated with standardized sodium thiosulfate solution using starch indicator (blue → colorless = endpoint). IV is calculated from the volume of thiosulfate used for the blank minus the sample.

C=C double bonds in unsaturated fatty acids are susceptible to oxidation by atmospheric oxygen — a process called lipid peroxidation or rancidity. Higher IV means more double bonds and faster oxidation. Polyunsaturated oils like flaxseed (IV >180) become rancid quickly and require antioxidants or refrigeration. Saturated fats (low IV) are more stable. IV therefore predicts shelf life — low-IV fats (coconut oil, palm kernel oil) are preferred for products needing long shelf stability without refrigeration or antioxidants.

In biodiesel, iodine value is used to assess fuel quality and oxidation stability. High-IV biodiesel (from linseed or fish oil, IV >120) is prone to oxidation, polymerization, and engine deposit formation. The European biodiesel standard (EN 14214) sets a maximum IV of 120 for biodiesel. Palm oil-derived biodiesel has low IV (~55) and excellent oxidation stability but poor cold-flow properties. Blending different feedstocks balances oxidation stability against cold-weather performance.