Optimization of CO2 Supercritical Extraction and Air-Drying Temperature Process on the Antimicrobial Properties of Pistacia lentiscus Leaves Essential Oil

Supercritical carbon dioxide extraction (SFE-CO2) is an efficient and environmentally friendly process for extracting bioactive compounds from plant material. This investigation examined the combined effects of air-drying temperature of the leaves and SFE-CO2 operating conditions on the extraction yield, volatile compound composition, and antimicrobial activity of Pistacia lentiscus leaf extracts. Extractions were performed at pressures ranging from 100 to 200 bar and temperatures ranging from 35 to 55 °C. Extraction yield increased with extraction pressure and temperature, while fresh leaves yielded the highest extract, highlighting the importance of pretreatment on extractability. Chemical analysis revealed notable variations in monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, and oxygenated sesquiterpenes depending on drying temperature and extraction parameters, confirming the high sensitivity of the volatile compound composition to processing conditions. Response surface methodology (RSM) was used to optimize process variables in order to enhance antimicrobial activity. The extracts inhibited both bacterial and fungal strains, confirming that the extraction conditions exert a direct influence on biological properties. The quadratic model identified the optimal combinations of drying and supercritical CO2 extraction parameters, thereby providing a rational strategy to maximize the antimicrobial potency of P. lentiscus extracts. Overall, controlling pretreatment and supercritical extraction conditions allows for targeted modulation of chemical composition and bioactivity, thereby promoting the development of natural antimicrobial agents and valuable functional components.