Formation of Secondary and Tertiary Volatile Compounds Resulting from the Lipid Oxidation of Rapeseed Oil

Abstract

The lipid oxidation of fats and oils leads to volatile organic compounds, having a decisive influence on the sensory quality of foods. To understand formation and degradation pathways and to evaluate the suitability of lipid-derived aldehydes as marker substances for the oxidative status of foods, the formation of secondary and tertiary lipid oxidation compounds was investigated with gas chromatography in rapeseed oils. After 120 min, up to 65 compounds were detected. In addition to secondary degradation products, tertiary products such as alkyl furans, ketones, and aldol condensation products were also found. The comparison of rapeseed oils, differing in their initial peroxide values, showed that the formation rate of secondary compounds was higher in pre-damaged oils. Simultaneously, a faster degradation, especially of unsaturated aldehydes, was observed. Consequently, the formation of tertiary products (e.g., alkyl furans, aldol adducts) from well-known lipid oxidation products (i.e., propanal, hexanal, 2-hexenal, and 2-nonenal) was investigated in model systems. The experiments showed that these compounds form the new substances in subsequent reactions, especially, when other compounds such as phospholipids are present. Hexanal and propanal are suitable as marker compounds in the early phase of lipid oxidation, but at an advanced stage they are subject to aldol condensation. Consequently, the detection of tertiary degradation products needs to be considered in advanced lipid oxidation.

Systematic Studies on the Antioxidant Capacity and Volatile Compound Profile of Yellow Mealworm Larvae (T. molitor L.) under Different Drying Regimes

“…Another indication of the oxidative milieu during freeze-drying is given by this study's headspace volatile compound screen. The GC-MS profiles of the freeze-dried mealworm larvae were far more enriched in aldehydes (secondary lipid degradation products) as well as 2-alkylfurans and methyl ketones (tertiary lipid degradation products) [29,64]. The Strecker aldehydes 2-methylpropanal, 3-methylbutanal and 2-methylbutanal were already detected in raw larvae, similar to the results of other studies [37,65].…”

“…They all contribute to the colour, flavour, nutritional and antioxidant properties of heat-treated foods. Likewise, lipid oxidation also generates numerous primary, secondary and tertiary oxidation products that influence shelf life and product properties such as taste, texture, mouthfeel and appearance [28,29]. In complex matrices-such as mealworm larvae-intermediates of the Maillard reaction and lipid oxidation will likely pass into interrelated routes and thus contribute in a coordinated manner to the properties of the dried insect [30].…”

Characterization of volatile compounds in evening primrose oil after γ‐irradiate

“…After irradiation, the OAV was changed with the concentration change of different compounds (Table 1). Hexanal, a suitable marker in the early phase of lipid oxidation, 27 the OAV was 20.13, 364.27, 272.27, respectively, after 1, 5, 10 KGy irradiation. The change is considerable, especially under 5 KGy irradiation; it suggests that the sample was degraded.…”

“…After irradiation, the OAV was changed with the concentration change of different compounds (Table 1). Hexanal, a suitable marker in the early phase of lipid oxidation, 27 the OAV was 20.13, 364.…”

Comparison of volatile flavor compounds in plant-based and real pork mince by Headspace-Gas Chromatography-Ion Mobility Spectrometry (HS-GC-IMS)

“…The other identified compounds (group 2 of Figure 2), such as 2-methyl pyrazine, 2,5-dimethyl pyrazine, 2-furfural, 2-acetylfuran, phenylacetaldehyde, methional, 2-acetylthiazole 2-methyl-1pentanol, (E)-2-hexenal, 2-hexanone, 2-octanone, isovaleric acid, hexanoic acid, propylacetate, methyl butanoate, butyl acetate, and isoamyl acetate, were mainly detected in raw PBPMs. Among these compounds, 2-methyl pyrazine, 2,5-dimethyl pyrazine, 2-furfural, 2-acetylfuran, phenylacetaldehyde, methional, and 2-acetylthiazole are typical products of the Maillard reaction (including Strecker degradation) (Cho et al, 2010;Xu et al, 2019), and (E)-2-hexenal is a well-known lipid oxidation-derived aldehyde (Grebenteuch et al, 2021). One possible source of these products is the flavoring agents that are added to these commercialized PBPM, and another possible source is the Maillard reaction and lipid oxidation, which occur during the PBPM manufacturing process (He et al, 2021).…”