Chemical and microbiological analyses of 25-year-old lemon essential oils

What is it about?

Essential oils (EOs) are volatile natural compounds widely used in perfumery, food, pharmaceuticals, and as solvents. Although their nominal shelf-life after opening is 12 months, their antibacterial and antiviral properties may enable longer preservation if properly stored. This study investigates the long-term stability of samples of lemon EOs accidentally stored in hermetically sealed glass bottles for 25 years. Comprehensive analyses were conducted to evaluate their chemical and biological properties. Gas chromatography with flame ionization detection (GCFID) was used to compare the aged samples to a genuine and organic certified reference essential oil (CREO) produced in Catania, Sicily in 2024 and bottled in functional units of 10 mL by LaborBio, Collegno (Turin, Italy). Additionally, microbiological tests and nuclear magnetic resonance (NMR) spectroscopy were performed to identify and characterize a white-grey precipitate found in the samples. The findings reveal that EOs can maintain their composition and functionality well beyond the expected shelf-life, suggesting significant opportunities for reducing industrial waste and optimizing storage practices.

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Photo by Bruno Brikmanis-Jurjans on Unsplash

Photo by Bruno Brikmanis-Jurjans on Unsplash

Why is it important?

The exceptional chemical and physical stability of these lemon EOs, stored for 25 years, highlights their potential for important industrial applications. The extended shelf life reduces the need for frequent production runs, thus reducing costs and environmental impact. This stability is particularly relevant for industries requiring high-quality raw materials, such as perfumery and maceuticals. From a broader perspective, this work represents a significant achievement in the field of duct preservation, providing valuable insights into the long-term stability of bioactive compounds. Long-term preservation of the chemical and microbiological lity of essential oils may lead to innovative strategies to improve the shelf-life of dietary supplements and tives. This has profound implications not only for the food industry but also for the cosmetics sector, where EOs may serve as key components in beauty creams and other personal care formulations.

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