Peroxide Value (PV) in Oils, Oilseeds, and Feed Materials

Peroxide Value (PV) measures the concentration of peroxides and hydroperoxides formed during the early stages of oil oxidation. It is widely used as an indicator of initial oxidative deterioration in fats and oils.
PV is typically the first measurable sign that an oil or fat-containing material is beginning to degrade.

PV is applied across a wide range of matrices, but interpretation depends on the material:
Refined food oils
‣ Used to assess freshness and shelf-life stability
‣ Low PV is expected in properly refined oils
Oilseeds (e.g. soybean, sunflower)
‣ PV can increase after mechanical processing due to exposure to oxygen
‣ Useful for assessing storage quality
Fishmeal
‣ PV can rise rapidly due to high polyunsaturated fat content
‣ However, peroxides may also break down quickly, limiting its reliability alone
Animal by-products (e.g. poultry by-product meal)
‣ Variable fat quality leads to inconsistent PV results
‣ Often used as an initial screening tool
In practice, PV is most useful when combined with other oxidation parameters.

Peroxides are unstable intermediates in the oxidation process.
Key characteristics:
‣ Form during primary oxidation
‣ Decompose into secondary products (aldehydes, ketones) over time
‣ Can decrease even as overall oxidation worsens
This leads to an important limitation:
‣ A low PV does not always mean good quality; it may indicate either:
     ‣ Fresh, unoxidised material
     ‣ OR advanced oxidation, where peroxides have already broken down
Factors influencing PV:
‣ Exposure to oxygen during storage
‣ Heat from processing (e.g. frying, pelleting, rendering)
‣ Light exposure
‣ Presence of pro-oxidant metals
‣ Antioxidant inclusion
Because of this behaviour, PV should not be interpreted in isolation.

Verification
‣ Confirms whether oils and raw materials are still within acceptable freshness limits
‣ Screens incoming materials for early oxidation
Quality control
‣ Tracks oxidation during storage and handling
‣ Identifies issues with storage conditions or processing
Formulation accuracy
‣ Prevents inclusion of already degraded fats into finished products
‣ Supports decisions on antioxidant use and shelf-life management

Real-world impact
‣ Early oxidation can progress rapidly if not controlled
‣ In feed materials, this can lead to reduced palatability and intake
‣ In food oils, it affects flavour, odour, and consumer acceptance
In practice, PV is rarely used alone. It is typically interpreted alongside:
‣ p-Anisidine Value (p-AV) → to assess secondary oxidation
‣ Totox value → to estimate overall oxidation status
‣ TBA (malondialdehyde) → for advanced oxidation