Essential oil production technologies: A systematic review of circular economy strategies and sustainability performance

Essential oil production is increasingly framed not only as an extraction challenge but as a circular biorefinery problem in which essential oil, hydrosol, process water, and solid residues should be jointly valorized. This systematic review synthesized evidence on production technologies and sustainability performance using a PRISMA 2020-informed design. Searches structured for Scopus and Web of Science logic and validated across publisher platforms identified 40 eligible studies published between 2021 and 2026. Six technology families were mapped, with microwave-assisted distillation and by-product or residue valorization dominating the field. Most studies reported yield and compositional quality gains, whereas far fewer quantified environmental burdens or economic feasibility. The evidence shows that device-level intensification alone rarely proves circularity; stronger sustainability claims emerged when intensified extraction was combined with hydrosol use, residue valorization, life cycle assessment, or techno-economic analysis. However, the literature remains constrained by heterogeneous metrics, laboratory-scale designs, and limited system-boundary reporting. Overall, the review finds that the most credible pathway toward sustainable essential oil production is not a single superior extractor, but an integrated process design coupling efficient recovery with verified co-product cascading and system-level evaluation.