Quantitative analysis of volatiles in edible oils following accelerated oxidation using broad spectrum isotope standards

Abstract

Analysis of food volatiles generated by processing are widely reported but comparisons across studies is challenging in part because most reports are inherently semi-quantitative for most analytes due to limited availability of chemical standards. We recently introduced a novel strategy for creation of broad spectrum isotopic standards for accurate quantitative food chemical analysis. Here we apply the principle to quantification of 25 volatiles in seven thermally oxidized edible oils. After extended oxidation, total volatiles of high n-3 oils (flax, fish, cod liver) were 120-170 mg/kg while low n-3 vegetable oils were <50 mg/kg. Separate experiments on thermal degradation of d5-ethyl linolenate indicate that off-aroma volatiles originate throughout the n-3 molecule and not solely the n-3 terminal end. These data represent the first report using broad-spectrum isotopically labeled standards for quantitative characterization of processing-induced volatile generation across related foodstuffs, and verify the origin of specific volatiles from parent n-3 fatty acids.

Deodorisation of fish oil by nanofiltration membrane process: focus on volatile flavour compounds and fatty acids composition

“…Heptanal and (E) ‐2‐octenal are typical compounds derived from fish oil oxidation (Giogios et al ., ). Furthermore, (E,E) ‐2,4‐heptadienal and 2‐pentenal, with a fishy and paint odour, respectively, can be ascribed to the oxidation of n‐3 fatty acids (Gómez‐Cortés et al ., ). The branched‐chain aldehyde, 2‐methylbutanal, is a well‐known aroma compound usually generated from Strecker reaction of isoleucine (Gu et al ., ).…”

Inhibitory Effect of Dihydrosphingosine with α-Tocopherol on Volatile Formation during the Autoxidation of Polyunsaturated Triacylglycerols

“…Our recent study demonstrated the preferential formation of acrolein and propanal in an early stage of the oxidation of soybean oil, linseed oil, echium oil, and fish oil TAG, whereas the major volatile composition changed thereafter 22 . Both acrolein and propanal are mainly formed from omega-3 PUFA, such as DHA 22:6n-3 , EPA 20:5n-3 , stearidonic acid 18:4n-3 , and α-linolenic acid ALA, 18:3n-3 18,27 . These n-3 PUFA are relatively more easily oxidized and decomposed than another major PUFA, linoleic acid 18:2n-6 .…”

The use of factorial design to evaluate the oxidation of oils containing different types of omega‐3 fatty acids

“…However, oils containing a higher proportion of long‐chain polyunsaturated fatty acids are more susceptible to oxidation . These polyunsaturated fatty acids contain 1,4‐ cis ‐pentadiene systems, which are prone to hydrogen abstraction and subsequent free radical oxidation reactions . Once oxidized, n3 FA can lose their functionality, leading to the formation of potentially toxic secondary products that lower food quality and safety , –.…”

“…The first aspect concerns the long time, in terms of analysis, for oxidative damage to occur in a commercial oil at room temperature . Usually, the oil is kept at 60 °C for a minimum of 15 days before secondary oxidative markers can be quantified by instrumental analysis such as gas or liquid chromatography . The second aspect is concerned with the secondary products produced from different types of n3 FA.…”