Optimizing postharvest quality of myrtle (Myrtus communis L.) essential oil extracts: effects of temperature and storage duration.

This study investigates the effects of storage conditions on the chemical composition and stability of Myrtus communis essential oil, collected from Firuzabad, Fars Province. A factorial design was employed with three storage temperatures (25 °C, 4 °C, and - 20 °C) and six storage durations (1-6 months). Essential oils were extracted from air-dried plant material via hydro-distillation and analyzed using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Principal component analysis (PCA), combined with specific selection criteria (SC), was applied to interpret the data effectively. The results indicate that lower storage temperatures, particularly - 20 °C, tend to better preserve esters such as linalyl acetate over six months, while monoterpene hydrocarbons such as α-pinene and 1,8-cineole appear relatively stable even at 25 °C. Refrigeration at 4 °C provided intermediate preservation. Some degradation of compounds may occur through hydrolysis, oxidation, or temperature-dependent rearrangements, although these mechanisms remain speculative as direct evidence from GC-MS was not obtained. Overall, the findings suggest that controlling storage temperature is important for maintaining the chemical integrity and potential therapeutic properties of M. communis essential oil, with implications for its use in pharmaceutical and cosmetic applications.