Effect of Pulsed Electric Field (PEF) Pretreatments on the Phytochemical Composition, Antioxidant, and Antimicrobial Properties of Sage Extracts

This study investigated the impact of pulsed electric fields (PEFs) on the phytochemical, antioxidant, and antimicrobial properties of extracts obtained from fresh and dried sage (Salvia officinalis L.). Extracts were characterized in terms of dry matter, phenolic content, and further profiled using HPLC-HRMS. Fresh sage extracts were richer in chlorophylls and chlorophyllides, whereas dried sage extracts contained significantly higher levels of total phenolics and pheophytins. Principal component analysis highlighted clear compositional differences between extracts obtained from fresh and dried sage. Although PEF had a limited impact on phenolic extraction from fresh sage, a pronounced increase was observed when applied to dried sage, likely due to electroporation facilitating solvent penetration in tissues collapsed upon drying. Antioxidant efficiency, expressed as chain-breaking phenolic ratios (DPPH, ABTS, and FRAP), increased with PEF intensity for both matrices, with extracts from fresh sage showing the most pronounced improvement. Antimicrobial testing demonstrated selective efficacy against gram-positive bacteria (Bacillus cereus and Staphylococcus aureus), with extracts from dried sage generally exhibiting stronger inhibition due to its higher phenolic content, whereas only the fresh sage extract treated at 8 kV/cm showed partial activity against Pseudomonas aeruginosa. No extract inhibited Escherichia coli or Salmonella enterica growth. Overall, PEF proved to be a valuable processing tool to enhance the extraction and functional properties of sage phytochemicals.