The application of nanotechnology to food, medical and pharmaceutical industries has received great attention from the scientific community. Driven by the increasing consumers' demand for healthier and safer food products and the need for edible systems able to encapsulate, protect, and release functional compounds, researchers are currently focusing their efforts in nanotechnology to address issues relevant to food and nutrition. Nanoemulsion technology is particularly suited for the fabrication of encapsulating systems for functional compounds as it prevents their degradation and improves their bioavailability. This review focuses on nanoemulsions and provides an overview of the production methods, materials used (solvents, emulsifiers, and functional ingredients) and of the current analytical techniques that can be used for the identification and characterization of nanoemulsions. Finally, nanotechnological applications in foods currently marketed are reported.

The physico-mechanical properties of 3 films composed by carvacrol, grape seed extract (GSE) and chitosan in different proportions were studied. The films, prepared by solvent casting technique with the following compositions of the casting solutions in carvacrol, GSE and chitosan: film-1: 9.6 ppm-684 ppm-1.25% w/v, film-2: 60 ppm-400 ppm-1.2% w/v and film-3: 90 ppm-160 ppm-1.24% w/v and were compared to a control (1.25% w/v chitosan) film. Mechanical, structural, barrier and colour properties of the films were evaluated. Film-3 presented the lowest water vapour and carbon dioxide permeabilities (WVP and CO 2 P) and tensile strength (TS) values and the highest oxygen permeability (O 2 P), whereas film-1 presented the highest water content and the lowest crystallinity, CO 2 P, TS and luminosity. These results suggest that in the range studied, carvacrol and GSE affect the film structure and its mechanical properties due to hydrophilic (GSE) and hydrophobic (carvacrol) compounds. This work will help the development of edible films, based on physico-mechanical properties, contributing to food preservation and shelf-life extension.

a b s t r a c tThis work evaluates the influence of the type of surfactant (Tween 20, SDS and DTAB) and processing conditions on the stability of oil-in-water nanoemulsions, measured in terms of hydrodynamic diameter (H d ), polydispersity index (PdI) and zeta potential (Zp). Nanoemulsions were prepared using high-pressure homogenization based on a 2 4 level factorial design. Results show that processing parameters such as homogenization pressure, surfactant concentrations and oil:water ratio significantly affected the values of H d and PdI of nanoemulsions. The value of H d of anionic nanoemulsions decreased (from 177 to 128 nm) with the increase of the homogenization pressure. The increase in the surfactant concentration and the decrease of the oil:water ratio lead to a decrease of H d for the cationic nanoemulsions (from 198 to 135 nm). The increase of the oil:water ratio lead to a decrease of H d for the non-ionic nanoemulsions (from 341 to 171 nm); this is contrary to the usual assumption that higher content in oil results in higher values of H d . Those nanoemulsions showed a good kinetic stability (evaluated after centrifugation, heating-cooling cycles and thermal stress) upon measuring the H d during 28 and 35 days of storage, without visual evidence of creaming and phase separation. After one year of storage the nanoemulsions produced with the anionic surfactant remained kinetically stable, without visual evidence of creaming and/or phase separation.