Chitosan-Enriched Carvacrol-Based Microemulsions as Sustainable Low-Sodium Brine Replacements for Green Table Olive Preservation

The conventional preservation of table olives in high-salt brine poses significant environmental (wastewater disposal) and nutritional (high sodium intake) challenges. This study investigated transparent chitosan (CS)-enriched carvacrol (CV)-based microemulsions (ME) as sustainable, low-sodium replacements for brine in preserving green table olives (cv. Chalkidiki). Three formulations were prepared: ME-CV, ME-CV-CS incorporating 1% chitosan, and ME-CV-GEL incorporating 1% gelatin. The central aim was to determine whether the cationic polysaccharide chitosan enhances the antimicrobial, colloidal, and antioxidant performance of CV-based ME. All ME exhibited droplet sizes below 20 nm (8.3–10.5 nm) and high optical clarity (UV-Vis transmittance > 96% at 600 nm). ME-CV-CS exhibited the lowest pH (3.68–3.72) and the highest ζ-potential (+30.2 mV), indicating superior colloidal stability and cationic antimicrobial potential. ME-CV-GEL provided the best color retention. However, gelatin interfered with the Folin–Ciocalteü assay. Overall, chitosan-enriched CV-based MEs offer a promising, transparent, and sustainable alternative to traditional brine. However, sensory evaluation (taste, texture, and overall acceptability) is required to confirm consumer acceptance and commercial viability.