Essential Oils of Dill and Nettle as a Natural Alternative to Reduce Pathogenic Bacteria on Dairy Production Surfaces

Abstract

Essential oils (EOs) have emerged as promising natural antimicrobials for food safety applications. However, their direct use on food-contact surfaces-such as wood and plastic, commonly employed in artisanal cheese production-has been scarcely explored. This study aimed to evaluate the antibacterial effects of dill (<i>Anethum graveolens</i>) and nettle (<i>Urtica dioica</i>) essential oils against <i>Listeria monocytogenes</i> and <i>Escherichia coli</i>, both in culture media and on inert surfaces. EOs were extracted via steam distillation and characterized by gas chromatography-mass spectrometry (GC-MS). Antimicrobial activity was assessed using agar diffusion and minimum inhibitory concentration (MIC) assays. In addition, bacterial reduction was quantified following EO application to contaminated wooden and plastic surfaces for 40 min. Dill EO exhibited a high anethole content (63.66%), while nettle EO was dominated by limonene (38.73%). Dill EO produced larger inhibition zones against <i>E. coli</i> (13.7 ± 1.5 mm) and <i>L. monocytogenes</i> (12.3 ± 1.5 mm) compared to nettle EO (6.3 ± 0.6 mm and 8.0 ± 1.7 mm, respectively). On plastic, both EOs achieved complete inhibition of <i>E. coli</i> (100%) and greater than 92% reduction in <i>L. monocytogenes</i>. On wood, dill EO maintained high efficacy (up to 87.9%), whereas nettle EO showed limited reduction (29.3%) against <i>L. monocytogenes</i>. These results demonstrate that EO efficacy is influenced by both surface type and target microorganism, supporting the potential of dill EO as a natural antimicrobial agent for surface sanitation in artisanal cheese production.