A way for improving the stability of the essential oils in an environmental friendly formulation

The essential oils (EOs) possess amazing properties explaining the interest for their applications in many essential domains. They also present the disadvantage of their chemical instability in the presence of air, light, moisture, and high temperatures. The paper focuses on two of the most known and used EOs, lavender and mint, respectively. The idea of the study was to protect them using the encapsulated systems. The originality of the work consists in the combination between the advantages of the molecular encapsulation of the EOs by cyclodextrins (CD) with the advantages offered by the sol-gel process. Original formulations have been processed by entrapping these essential oils in silica matrices obtained from a colloidal silica sol by the aqueous route of the sol-gel method. Another non-toxic ingredient, β-cyclodextrin, able to form inclusion complexes (ICs) with the essential oils has been used. The characterization methods (chromatography, UV-vis, IR, and NMR spectroscopies) have evidenced the presence of the mentioned inclusion complexes. Due to their formation, which modifies the water solubility of the EOs, the chromatographic analysis was possible using water as solvent, which is a novelty in EOs determinations. Protected from both the cyclodextrin and silica matrix, the essential oils became more resistant versus the effects of the environment factors. Thus, the resulted powders can find applications in domains as agriculture, food industries, cosmetics, pharmaceutical, and medicine.