Encapsulation of essential oil of Origanum vulgare in lipid nanostructured systems: production, characterization, shelf-life and antimicrobial activity

Abstract

Essential oils are complex substances composed of several different substances, and are characterized by high volatility and odour, and are obtained from different parts of the plants (roots, leaves, seeds). Another interesting characteristic of the essential oils is their antimicrobial and antifungal action, which can be of great utility in food preservation. Among the most studied essential oils due is the oregano oil, whose two main active principles are thymol and carvacrol. It shows a wide spectra of antimicrobial action (E. coli, L. monocytogenes, S. aureus, S. thyphymorium, B. cereus), extremely interesting in the preservation of several food matrices. The application of essential oils with this purpose, however, faces some technological challenges, as the low stability during storage period, as well as the difficulty of incorporating them in aqueous formuations. In order to overcome such problems, and also add the possibility of controlled delivery of the antimicrobial compounds, microencapsulation in nanostructured lipid systems is a feasible alternative. Due to their nanometric size, these systems can interact more effectively with the food matrix, and really incorporate the benefits of a controlled delivery system. Thus, in this context, and taking into account the consumer market is asking for the replacement of artificial by natural ingredients in food formulations, the main aim of this proposal is to investigate the nanoemulsion production in order to encapsulate oregano oil, and test their antimicrobial action in vitro. The nanoemulsions will be produced by a low energy method (PIT method, or phase inversion temperature). The proposal includes the determination of both process parameters, the physical-chemical caracterization of the nanostructured lipid systems, the evaluation of their shelf-life, and, finally, the evaluation of their potential antimicrobial action. (AU)