Agustina Orden

Postharvest losses in aromatic crops often result from the discard of biomass exposed to environmental conditions that affect visual quality but not necessarily its biochemical value. In oregano ( Origanum vulgare L.) production systems, plant material left in the field after harvest is frequently exposed to nocturnal dew and subsequently rejected. This study evaluated the effect of dew exposure on essential oil yield, chemical composition, physicochemical characteristics, and biological activity. Dew exposure reduced essential oil yield by approximately 40%, indicating an effect on extraction efficiency. However, no major changes were observed in the chemical composition or physicochemical parameters of the oils, with thymol remaining the dominant compound. In addition, antioxidant capacity, polyphenol oxidase inhibition, and antifungal activity against Aspergillus parasiticus , Fusarium verticillioides , and Eurotium amstelodami were preserved. These results demonstrate that biomass currently discarded based on visual criteria retains its chemical identity and functional properties. From a biomass valorization perspective, dew-exposed oregano represents a viable raw material to produce value-added essential oils, contributing to reduced postharvest losses and improved resource efficiency in aromatic crop systems. Statement of Novelty The novelty of this study lies in demonstrating that oregano biomass discarded after nocturnal dew exposure retains its chemical identity and biological functionality, despite a significant reduction in essential oil yield. While postharvest losses in aromatic crops are typically assessed based on visual quality, this work provides experimental evidence that such criteria may not reflect the true value of the biomass. By integrating compositional, physicochemical, and bioactivity analyses, the study shows that dew-exposed material remains a viable source of functional essential oils. This shifts the perspective from quality loss to resource recovery, supporting biomass valorisation strategies and offering a practical approach to reduce postharvest waste in oregano production systems.