Phenolics can trap lipid-derived reactive carbonyls as a protective function that diminishes the broadcasting of the lipid oxidative damage to food macromolecules. In an attempt to clarify the trapping of 2,4-alkadienals by phenolics, this study analyzes the reactions of 2,4-hexadienal, 2,4-heptadienal, and 2,4-decadienal with 2-methylresorcinol. These reactions produced (E)-4-(alk-1-en-1-yl)-8-methyl-2,7-bis(prop-1-en-2-yloxy)chromanes, which were isolated and characterized by 1D and 2D NMR and MS. Carbonyl-phenol adduct formation was favored at pH > 7 and moderate temperatures (25-80 °C). Adducts were quantified and shown to be produced as a mixture of diastereomers. Diastereomers 2R,4S plus 2S,4R were formed to a higher extent than diastereomers 2R,4R plus 2S,4S under the different conditions assayed, although activation energies (Ea) for the formation of all of them was mostly the same (∼62 kJ·mol-1). These results show that phenolics can trap 2,4-alkadienals and provide the basis for the later detection of the formed adducts in food pro[ducts.
Keywords: (2E,4E)-Deca-2,4-dienal (PubChem ID: 5283349); (2E,4E)-Hepta-2,4-dienal (PubChem ID: 5283321); (2E,4E)-Hexa-2,4-dienal (PubChem ID: 637564); 2-Methylresorcinol (PubChem ID: 11843); Alka-2,4-dienals; Carbonyl-phenol reactions; Lipid oxidation; Maillard reaction; Reactive carbonyls.
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