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What is POV in Oil?

Published in Food Chemistry 3 mins read

POV in oil refers to the Peroxide Value, which is an indicator used to determine the extent of oxidation in fats and oils. Specifically, it measures the concentration of peroxides and hydroperoxides formed during the initial stages of lipid oxidation.

Understanding Peroxide Value (POV)

  • Definition: The Peroxide Value (POV) is defined as the amount of peroxide oxygen per kilogram of fat or oil, expressed in milliequivalents (meq) of peroxide oxygen per kilogram.

  • Significance: The POV is a critical parameter for assessing the quality and stability of fats and oils. High POV indicates a higher degree of oxidation, which can lead to rancidity, off-flavors, and a reduction in nutritional value.

  • Oxidation Process: Unsaturated fats and oils are susceptible to oxidation when exposed to oxygen, light, heat, and certain metals. This process leads to the formation of peroxides as primary oxidation products.

How POV is Determined

The determination of POV typically involves a chemical titration method. In brief:

  1. The fat or oil sample is dissolved in a suitable solvent.
  2. Potassium iodide (KI) is added, which reacts with the peroxides present in the sample, releasing iodine (I2).
  3. The released iodine is then titrated with a standard solution of sodium thiosulfate (Na2S2O3) using starch as an indicator.

Acceptable POV Levels

Acceptable POV levels vary depending on the type of oil and its intended use. Generally:

  • Freshly refined oils: POV should be very low, ideally below 5 meq/kg.
  • Edible oils: POV limits are often set by regulatory bodies to ensure consumer safety and product quality.
  • Oils approaching rancidity: POV will be significantly higher, often exceeding 10-20 meq/kg or more.

Factors Affecting POV

Several factors can influence the POV of oils:

  • Storage Conditions: Exposure to air, light, and heat accelerates oxidation and increases POV.
  • Processing Methods: Refining processes can initially lower POV, but subsequent handling can impact it.
  • Antioxidants: The presence of natural or added antioxidants can inhibit oxidation and maintain lower POV.
  • Packaging: Appropriate packaging that minimizes exposure to oxygen and light is essential.

Example

Imagine two bottles of olive oil:

  • Bottle A: Stored in a dark, cool place in a sealed container. Its POV is measured at 2 meq/kg.
  • Bottle B: Left open on a sunny windowsill. Its POV is measured at 15 meq/kg.

Bottle B is clearly more oxidized and likely to exhibit signs of rancidity sooner.

In summary, Peroxide Value (POV) is a crucial measurement for evaluating the quality and stability of oils by quantifying the level of oxidation products present.

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