In this study, laurel essential oils were obtained
by using solvent-free microwave extraction (SFME) and hydrodistillation (HD)
methods from Laurus nobilis leaves
and determined their antioxidant and antimicrobial activity. Extraction time
was reduced by about 43% in SFME at 622 W and 67% in SFME at 249 W compared to
hydrodistillation. Essential oil of laurel was extracted by SFME at 622 W
(100%) and 249 W (40%) power levels and HD inhibited oxidation generated by
ABTS radical by 93.88%, 94.13% and 92.06%, respectively. Trolox equivalent
antioxidant capacities (TEAC) of essential oils were 0.18 mM/mL oil for SFME at
622 W, 1.36 mM/mL oil for SFME at 249 W and 2.40 mM/mL oil for HD (p < 0.05).
Essential oils of L. nobilis were extracted by SFME at 100%
and 40% power levels and HD inhibited linoleic acid peroxidation by 70.57%,
63.53% and 89.18% respectively. Inhibition effects of laurel essential oils
obtained by SFME at different power levels and HD on DPPH radical cation
oxidation were not significantly different. The strongest antioxidant activity
against DPPH radical was found in the essential oil obtained by SFME at 100%
power level. Essential oils displayed antimicrobial activity against Staphylococcus
aureus 6538P, Escherichia coli O157:H7 and Salmonella typhimurium NRRL E 4463 except for Listeria monocytogenes.
The inhibitory effect on Staphylococcus
aureus 6538P survival of laurel oil obtained from SFME by using lower power
level was found to be lower than that obtained from SFME at 100% power level
and HD (p < 0.05).