Malondialdehyde, 4‐Hydroxy‐2‐Hexenal, and 4‐Hydroxy‐2‐Nonenal in Vegetable Oils: Formation Kinetics and Application as Oxidation Indicators

The formation of three toxic reactive aldehydes, malondialdehyde (MDA), 4‐hydroxy‐hexenal (HHE), and 4‐hydroxy‐2‐nonenal (HNE), is investigated in five commonly consumed vegetable oils using a method based on the Schaal oven test. HHE is only detected in linseed oil (LO) and rapeseed oil (RO), while MDA and HNE are found to be present in all tested oils. The formation potential of MDA, HHE, and HNE in the tested oils is closely related to the initial polyunsaturated fatty acid (PUFA) content in the oil. Correlation analyses reveal low correlation coefficients for MDA, determining its unsuitability to evaluate the oxidation of oils with low PUFA content, such as palm oil and camellia oil; in contrast, HHE and HNE show sufficient correlations with other oxidation indices in all tested oils. Furthermore, regression analysis indicates that HHE content can predict the oxidation of ω‐3 type oil, while HNE content can estimate oxidative deterioration of ω‐6 type oils. Particularly, HNE content can also evaluate the oxidation of ω‐9 type oils such as PO and CLO with relatively low PUFA level for the high correlations (>0.991, P < 0.01) toward the total oxidation value (TOTOX). Practical Applications: Edible oil consumption continues to increase worldwide. Therefore, it is very important to understand the conditions under which potentially health‐damaging compounds are formed in these oils and to develop methods to inhibit their formation or eliminate them from the oils. This study investigates the formation of three toxically reactive aldehydes, namely MDA, HHE, and HNE, through lipid oxidation, specifically PUFA peroxidation. The application of these aldehydes as oxidation indicators for different vegetable oils is also explored. This work could prove beneficial for the quality control of vegetable oils in the edible oil industry. The formation of three toxic aldehydes, MDA, HHE, and HNE in different types of vegetable oils is investigated. Considerable amounts of MDA, HHE, and HNE is found in all the tested oils. The results show the formation of these three aldehydes is competitive. Besides, MDA content is not appropriate to evaluate the oxidation of oils with low PUFA content, such as PO and CLO; while HHE and HNE can characteristically depict the oxidation of ω‐3 and ω‐6 type oil.