A rapid method for determining the oxidation of n‐3 fatty acids

Abstract

The stability of unsaturated fatty acids to oxidation was monitored by following gas chromatographic (GC) analyses of headspaee volatiles in comparison to changes in polyunsaturated fatty acids (PUFA) and increases in malonaldehyde v/a the 2-thiobarbituric (TBA) assay. Pure standards of linoleic acid (Lo) and n~ fatty acids [eicosapentaenoic (EPA) and docosahexaenoic acid (DHA)] were added to headspace vials, equilibrated in air for 10 mln, followed by heating at 80°C in teflon~apped vials for different time intervals. Headspace analysis showed inc~mses in acetaldehyde, propenal, and propanal, corresponding to the oxidation of n-3 fatty acids, whereas hexanal production corresponded to losses of linoleic acid. The analysis of pro panal by GC-headspace after only five minutes of heating appeared to be the most effective method of monitoring the oxidation of n-3 fatty acids, as indicated by correlations between TBA values and loss of PUFA. The oxidation of I~ EPA and DHA appeared to be a function of the number of double bonds. Correlations between PUFA depletion, TBA values and volatile formation indicate that under the prescribed conditions of this experiment, GCheadspace analysis of propanal and pentane/hexanal is an excellent method for following the oxidation of selected n-3 fatty acids and linoleic acid.

Docosahexaenoic Acid is More Stable to Oxidation when Located at the sn‐2 Position of Triacylglycerol Compared to sn‐1(3)

“…There were also several other compounds common to both pairs of isomers but they were not fully characterized. Propanal has widely been used as an oxidation marker for oils containing n-3 PUFA, especially fish oils where EPA and DHA are abundant [17][18][19][20]. Other oxidation markers include 1-penten-3-one [21,22] and trans, trans-2,4-heptadienal [21][22][23].…”

Effect of domestic processing on bioactive compounds

“…Polyunsaturated fats are more susceptible to oxidation during heating than monounsaturated fats. Heating at different cooking temperatures leads to an increase in volatile compounds such as acetaldehyde, propenal, and propanal resulting from x-3 fatty acids oxidation, whereas the formation of compounds such as hexanal corresponds to losses of linoleic acid (Boyd et al 1992). Dienaldehydes are also by-products of PUFA peroxidation and they are commonly found in many foods or food-products, like heated oils.…”

Spray‐dried encapsulation of Conjugated Linoleic Acid (CLA) with polymeric matrices

“…Pentanal and hexanal are the major volatile products of linoleic acid oxidation. 36 Four major volatile compounds were present in the samples as identified by GC-MS: pentanal, hexanal, heptanal and traces of octanal. Hexanal was the predominant volatile and it is considered to be a good indicator for the evaluation of oil oxidation.…”