Encapsulation of essential oils in polymer-based nanocarriers for food applications.

OBJECTIVE In recent years, there has been growing interest in essential oils (EOs) and their application in food preservation. This is due to the progressive increase in food-borne diseases and adverse consumer perception towards synthetic preservatives. Nanoencapsulation of plant essential oils (GRAS substances) with antimicrobial activity represents a valid approach to overcome their low solubility in water, to protect them from food interaction, and increase their concentration in food area, such as water-reach phase or liquid-solid interface, where microorganisms are more frequently located. Differently from microencapsulation, nanoencapsulation due to the subcellular size may increase the passive cellular absorbtion mechanisms and the bioactivity. This work is focused on the polymeric-based nanocarries of two antimicrobial EOs from Origanum vulgare L. and Thymus capitatus L. in order to enhance their biological activity against food-borne pathogenic microorganisms. METHODOLOGY The nanocapsules (NCs) were formed by interfacial deposition of preformed polymer method. Size and polydispersity index of NCs were derived from DLS analysis. Encapsulation efficiency (EE%) was calculated by the amount of EO into NC, obtained from UV-Vis analysis. Stability was monitored overtime. The EOs were prepared from the air-dried aerial part of the plant by hydro-distillation. MIC and MBC determinations were carried out on three different microbial strains to evaluate the antimicrobial activity of the nanostructured systems RESULTS The results obtained (EE between 80-85%, size range of 140-170 nm, stability overtime, and microbiological activity) are encouraging and make these EOs-NCs suitable for application in food preservation, topic of great interest in industrialized countries.