Edible films including active ingredients can be used as an alternative to preserve food products. Essential oils (EOs) exhibit antimicrobial activity against pathogenic microorganisms but their low water solubility limits the application in foods. To improve water dispersion and protect EOs from degradation, nano-sized emulsions emerge as a viable alternative. Nanoemulsions containing EOs and polysaccharides could be used to form edible films with functional properties. This study was focused on the evaluation of physical, mechanical and antimicrobial properties of alginate-based edible films formed from nanoemulsions of EOs. Nanoemulsions containing thyme (TH-EO), lemongrass (LG-EO) or sage (SG-EO) oil as dispersed phase and sodium alginate solution as continuous phase were prepared. The average droplet size of nanoemulsions was reduced after the microfluidization treatment exhibiting multimodal size distributions. The zeta-potentials of nanoemulsions were between 41 mV and 70 mV depending on the type of EO used. The lowest whiteness index was found in SG-EO nanoemulsions, whereas those containing TH-EO showed the highest value. Films formed from SG-EO nanoemulsions exhibited higher transparency, water vapor resistance and flexibility than films formed from TH-EO or LG-EO. Edible films containing TH-EO were those with the strongest antimicrobial effect against inoculated Escherichia coli, achieving up to 4.71 Log reductions after 12 h. Results obtained in the present work evidence the suitability of using nanoemulsions with active ingredients for the formation of edible films, with different physical and functional properties. (C) 2015 Elsevier Ltd. All rights reservedThis research was supported by the Ministerio de Ciencia e Innovación (Spain) throughout projects ALG2009-11475 and ALG2012-35635. Author Acevedo-Fani also thanks to the University of Lleida for the pre-doctoral grant. Author Martín-Belloso acknowledges to the Institució Catalana de Recerca I Estudis Avançats (ICREA) for the Academia 2008 Award

Background: Nowadays, consumers are increasingly demanding high-quality, safe and healthy food products. Nanostructured emulsions and nanolaminates may have the potential to protect and transport lipophilic and hydrophilic active compounds commonly incorporated to food products, such as natural antimicrobials and nutraceuticals, while protecting or even enhancing their functional properties. Scope and approach: This review deals with the most important aspects concerning to the use of nanostructured emulsions and nanolaminates as delivery systems of active ingredients, including the advantages and challenges of incorporating plant-derived antimicrobials and nutraceuticals in foods, relevant factors affecting the formation of these nanostructures, fabrication methods, their advantages as delivery systems, and the current trends in food applications. In addition, concerns regarding the potential toxicity of nanomaterials are also discussed. Key findings and conclusions: The successful production of nanostructured emulsions and nanolaminates depends on several physicochemical factors that should be controlled in order to reach stable systems. Research evidences that nanostructured emulsions and nanolaminates are able to improve the delivery and biological activity of encapsulated active compounds. Antimicrobial and bioactive nanostructured emulsions and nanolaminates exhibit some promising advantages in food preservation and may represent a new strategy to produce functional foods. However, the knowledge in this area is still limited. The potential toxicological effects of nanostructured delivery systems are a current concern. Therefore, future investigations should be directed towards more comprehensive studies to shed light on the formation, physicochemical stability, functional performance, interactions with food matrices and toxicity of nanostructured delivery systems before their commercialization.This research work was supported by the Ministry of Science and Innovation (Spain) [ALG2009-11475, ALG2012-35635, ALG2015-65975-R]. Also, author Acevedo-Fani thanks to the University of Lleida for the pre-doctoral grant