Table 5 Lipid peroxidation indices

Peroxide value (PV)

Measure of lipid peroxides and hydroperoxides.

p-Anisidine value (AnV)

Measure of the amount of the high molecular weight saturated and unsaturated aldehydes.

Thiobarbituric acid reactive substance concentration (TBARS)

Measure of carbonyl-containing secondary lipid oxidation products formed from the decomposition of hydroperoxides. Developed to detect malondialdehyde, although other carbonyl compounds can also contribute to the TBARS values.

Hexanal

Measures major secondary lipid oxidation products produced from the termination phase during the oxidation of linoleic and other ω-6 fatty acids.

2,4-decadienal (DDE)

An aldehyde derived from the peroxidation of linoleic acid.

4-hydroxynonenal (HNE)

An α, β-unsaturated lipophilic aldehyde formed from the peroxidation of polyunsaturated ω-6 fatty acids, such as linoleic or arachidonic acid.

Triacylglycerol dimers and polymers

Polymeric compounds formed during the late phases of peroxidation. Quantification of compounds based on molecular size using size exclusion chromatography or a relative value using viscosity.

Active oxygen method stability (AOM)

A predictive method where purified air is bubbled through a lipid sample at 97.8 °C, and the PV of the lipid is determined at regular intervals to determine the time required to reach a PV of 100 mEq/kg lipid (recorded as h), or the PV of the lipid is determined at a predetermined time endpoint, such as at 20 h (recorded as mEq/kg lipid).

Oil stability index (OSI)

A method whereupon air passes through a lipid under a specific temperature, at which point volatile acids decomposed from lipid peroxidation are driven out by the air and subsequently dissolved in water thereby increasing its conductivity. The conductivity of the water is constantly measured, and the OSI value is defined as the hours required for the rate of conductivity to reach a predetermined level.