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Table 1 Compounds measured and assay limitations of indicative tests

From: Evaluating the quality of feed fats and oils and their effects on pig growth performance

Indicative measure Peroxidation compounds detected Limitations
PV Peroxides and hydroperoxides Some procedures may be too subjective. Peroxides may be undetectable in lipids exposed to >150°C. Should be used in conjunction with TBARS and AnV when assessing peroxidation.
TBARS Malondialdehyde Not specific to malondialdehyde because 2-alkenals, 2,4-alkedienals can react with thiobarbituric acid. Different methodologies are used making inter-laboratory comparisons difficult.
AnV Aldehydes Not specific to a particular aldehyde because 2-alkenals, 2,4-alkedienals can react with p-anisidine under acidic conditions.
Conjugated dienes Primary peroxidation compounds formed after a double bond rearrangement in peroxides Less sensitive compared to PV. Carotenoids are absorbed in the same wavelength range which can cause misleading results.
TOTOX value Sum of AnV (or TBARS) and 2 × PV. Measures both primary and secondary peroxidation compounds. Increases the lack of specificity inherent with AnV (or TBARS) and PV.
Carbonyls Secondary peroxidation compounds including aldehydes and ketones. Lack of specificity and tendency to be influenced by non-carbonyl compounds.
Hexanal Specific carbonyl compound formed during the termination phase of peroxidation when linoleic acid (C18:2 n-6) or other ù-6 fatty acids are peroxidized. Volatile at high temperatures and may provide a misleading indication of extent of peroxidation.
DDE Specific aldehyde derived from linoleic acid (C18:2 n-6) during peroxidation. Complicated and expensive assay requiring gas chromatography and mass spectrophotometry.
HNE α, β-unsaturated lipophilic aldehyde formed during lipid peroxidation of n-6 polyunsaturated fatty acids (i.e. arachidonic and linoleic acid) Complicated and expensive assay.
Triacylglycerol dimers and polymers Polymeric compounds formed during the late phases of peroxidation. Measured with size exclusion chromatography. Limited information on their use in evaluating lipid quality and effects on animal health.
Oxiranes Cyclic compounds produced during peroxidation. Assay not specific to oxiranes because it can also detect carbonyls and conjugated dienes.
Non-elutable material Gas–liquid chromatography procedure that estimates the non-elutable material of a lipid after a correction for glycerol. Collectively measures most degraded chemical structures of a lipid.