Peroxyl Radical Trapping Antioxidant Activity of Essential\nOils and Their Phenolic Components

Essential\noils (EOs) are gaining importance as sustainable food\nantioxidants, but kinetic data on peroxyl radical trapping are missing.\nThirteen EOs from 11 botanical species were studied in the inhibited\nautoxidation of cumene by oxygen-uptake kinetics. EOs of Juniperus oxycedrus, Syzygium aromaticum, Thymus vulgaris, Thymbra capitata, Betula alba, Pimenta racemosa, and Satureja montana, containing 23–86% phenolic\ncomponents by gas chromatography/mass spectrometry (GC–MS)\nanalysis, afforded inhibition rate constants <i>k</i><sub>inh</sub> in the order of 10<sup>4</sup> M<sup>–1</sup> s<sup>–1</sup> at 30 °C similar to reference butylhydroxytoluene\n(2,6-di-<i>tert</i>-butyl-4-methylphenol) (BHT). They matched\nor outperformed BHT in the protection of olive oil. The EOs Daucus carota and Cedrus atlantica with <1% phenols and those of Apium graveolens and Tagetes minuta with no phenolics\nhad no chain-breaking activity. Key components carvacrol, thymol,\neugenol, dihydroeugenol, umbelliferone, conyferyl alcohol, <i>o</i>-cresol, <i>m</i>-cresol, <i>p</i>-cresol,\n4-allylphenol, 2,3-xylenol, 2,4-xylenol, and phenol had <i>k</i><sub>inh</sub> in the range of 10<sup>3</sup>–10<sup>4</sup> M<sup>–1</sup> s<sup>–1</sup> and, along with EOs\ncontaining them, could potentially replace BHT in the protection of\nfood products.