Chemical Composition, Antioxidant and Antimicrobial Activities ofThymus capitataEssential Oil with Its Preservative Effect againstListeria monocytogenesInoculated in Minced Beef Meat

摘要

The chemical composition, antioxidant and antimicrobial activities, and the preservative effect ofThymus capitataessential oil againstListeria monocytogenesinoculated in minced beef meat were evaluated. The essential oil extracted was chemically analyzed by gas chromatography-mass spectrometry. Nineteen components were identified, of which carvacrol represented (88.89%) of the oil. The antioxidant activity was assessedin vitroby using both the DPPH and the ABTS assays. The findings showed that the essential oil exhibited high antioxidant activity, which was comparable to the reference standards (BHT and ascorbic acid) with IC50values of 44.16 and 0.463μg/mL determined by the free-radical scavenging DPPH and ABTS assays, respectively. Furthermore, the essential oil was evaluated for its antimicrobial activity using disc agar diffusion and microdilution methods. The results demonstrated that the zone of inhibition varied from moderate to strong (15–80 mm) and the minimum inhibition concentration values ranged from 0.32 to 20 mg/mL. In addition, essential oil evaluatedin vivoagainstListeria monocytogenesshowed clear and strong inhibitory effect. The application of 0.25 or 1% (v/w) essential oil ofT. capitatato minced beef significantly reduced theL. monocytogenespopulation when compared to those of control samples (P-value  <0.01).