Abstract
Ziziphora tenuior L. is an endangered medicinal plant valued for its essential oil with strong antimicrobial and antioxidant properties. This study aimed to assess how storage temperature and duration influence the chemical composition of its essential oil. The oil was obtained from air-dried aerial parts via hydro distillation and stored for three months under three temperature conditions: room temperature (25 °C), refrigeration (4 °C), and freezing (-20 °C). Gas chromatography was used for compound identification, and the data were analyzed using Principal Component Analysis (PCA) and Selection Criteria (SC). Results showed significant degradation of low-boiling-point compounds at room temperature; notably, pulegone declined from 42.84% to 7.86%, and cis-carvone from 10.1% to 0.99%. In contrast, samples stored at freezing temperature retained a more stable chemical profile. These findings emphasize the importance of cold storage in preserving the chemical integrity and biological potential of essential oils, supporting their sustainable use in pharmaceutical, food, and health-related applications. To our knowledge, this is one of the first studies to comprehensively evaluate the time, temperature interaction on the stability of Z. tenuior essential oil. The outcomes can help establish standard postharvest practices for maintaining the quality of essential oils derived from endangered medicinal plants.