The Structure–Activity Relationship of Flavonoids in Inhibiting Aldehyde Emissions from Heated Soybean Oil

Cooking oil fumes contain various volatile organic compounds, such as aldehydes, which are major indoor air pollutants. Our previous study found that quercetin significantly inhibited the aldehyde emissions from heat-treated soybean oil. In this study, a simulated frying system was established to evaluate the inhibitory effects of 18 flavonoids with different structures on aldehyde emissions from heat-treated oil, and the structure–activity relationship was analyzed. The results showed that the flavonoids with an o-dihydroxyl group (3′,4’-o-dihydroxyl) in the B-ring and containing a 2,3 double bond and a 4-carbonyl group in the C-ring had stronger inhibition efficiency on the emissions of aldehydes. Flavanols containing galloyl groups have a strong inhibitory effect on aldehyde emissions. Isoflavones showed a relatively poor inhibitory efficiency. Further studies showed that flavonoids have selective inhibitory effects on the emissions of aldehydes. For example, flavonols exhibit stronger inhibitory activity against the emissions of 2-butenal, 2-ethylacrolein, t-2-hexenal, heptanal, octanal, and t,t-2,4-heptadienal. Flavanols exhibit stronger inhibition, specifically against the emissions of hexanal, heptanal, heptenal, and octanal. In addition, there was no significant correlation between the antioxidant activity of flavonoids and their inhibitory effects on aldehyde emissions. This study revealed the structure–activity relationship of flavonoids in inhibiting aldehyde emissions from heat-treated soybean oil and provided theoretical support for selecting appropriate natural plant compounds to inhibit aldehyde emissions from heated oil and reduce indoor air pollution.