Effect of distillation method on the antimicrobial potential and composition of Roman Chamomile ( <i>Chamaemelum nobile</i> (L.) All.) essential oil and hydrolate

Roman chamomile is a perennial herbaceous plant that has been widely cultivated for its medicinal and ornamental properties. This study investigated the chemical composition, sensory properties, and antimicrobial potential of essential oils (EOs) and hydrolates (HYs) extracted through steam distillation (SD) and hydro-distillation (HD) from Roman chamomile grown in Serbia. GC-MS analysis showed that EOs were rich in esters such as isoamyl tiglate (21.1-32.5%) and isobutyl angelate (28.5-35.7%), while HYs contained trans-pinocarveol (20.9-22.7%) and pinocarvone (14.8-19.5%) as dominant compounds, with concentrations varying depending on the extraction method. These differences influenced sensory properties and were clearly distinguished in a PCA biplot. In general, the EOs exhibited a strong herbal and spicy aroma with floral, fruity, and minty undertones, while the HYs displayed a herbal scent with minty, ethereal, and green notes. Additionally, the antimicrobial, antibiofilm, and antiadhesion activities of the samples were evaluated against pathogens, including Salmonella enterica serovar Typhimurium, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, E. hirae, Staphylococcus aureus, and S. epidermidis. Results showed that EOs exhibited strong antimicrobial activity, with inhibition zones up to 40 mm and MIC values using diluted EOs, while HYs had no significant effects. Multivariate and in silico analyses indicated that the antimicrobial activity of EOs is likely due to the synergistic effects of fatty acid esters, which also contribute to their pleasant aroma and potential for cosmetic use. In contrast, the aroma compounds in HYs were not associated with antimicrobial properties. Since HYs are largely by-products of EO extraction, further research is needed to explore their biological activities and potential applications.