Contents lists available at ScienceDirect Journal of Functional Foods journal homepage: www.elsevier.com/locate/jff Evaluating the behaviour of curcumin nanoemulsions and multilayer nanoemulsions during dynamic in vitro digestion Hélder D. Silva a , Joana Poejo b , Ana C. Pinheiro a,c, ⁎ , Francesco Donsì d , Ana Teresa Serra c,e , Catarina M.M. Duarte c,e , Giovanna Ferrari d,f , Miguel A. Cerqueira g , António A. Vicente a a Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal b Department of Biochemistry and Molecular Biology, Faculty of Sciences, and Institute of Molecular Pathology Biomarkers, University of Extremadura, Badajoz, Spain c IBET, Instituto de Biologia Experimental e Tecnológica, Avenida da República, Quinta-do-Marquês, Estação Agronómica Nacional, Apartado 12, 2781-901 Oeiras, Portugal d Department of Industrial Engineering, University of Salerno, Italy e Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. Da República, 2780-157 Oeiras, Portugal f ProdAl Scarl, Competence Center on Agro-Food Productions, University of Salerno, Italy g International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal ARTICLE INFO Keywords: Layer-by-layer Polyelectrolytes Multilayer nanoemulsions Lipid digestion Bioaccessibility and cytotoxicity ABSTRACT Nanoemulsions can be used to improve the bioaccessibility of lipophilic bioactive compounds, such as curcumin, being their behaviour highly influenced by their interfacial properties. The effect of chitosan and alginate layers’ deposition on curcumin nanoemulsions’ behaviour during in vitro digestion was evaluated using a dynamic gastrointestinal system. Results showed that polyelectrolyte layers’ deposition improved curcumin antioxidant capacity during in vitro digestion. In addition, multilayer nanoemulsions showed a better control of the rate and extent of lipid digestibility by decreasing free fatty acids release, compared to uncoated nanoemulsions. However, a lower curcumin bioaccessibility was observed for multilayer nanoemulsions. Although cytotoxicity assays revealed that both nanosystems are toxic due to the use of sodium dodecyl sulphate (SDS), nanosystems were 3.3-fold less toxic than SDS itself. This study showed that multilayer nanoemulsions could be used to increase satiety by retarding lipid di- gestion, which can be important for functional foods development for combating obesity. 1. Introduction Consumers’ demands for new and healthier foods are encouraging the food industry to seek for new strategies to fortify food products with bioactive compounds, turning foods into products that promote health and wellness (Cerqueira et al., 2013; Silva, Cerqueira, & Vicente, 2012, 2015b). Some of these bioactive compounds are lipophilic often re- sulting in low bioavailability, whereas some are pH- and temperature- sensitive, being prone to oxidative and chemical degradation (Guttoff, Saberi, & McClements, 2015; Mayer, Weiss, & McClements, 2013; McClements, 2015; Zou et al., 2015). Lipid-based delivery systems can be designed to encapsulate, protect and control/trigger the release of bioactive compounds at specific locations within the gastrointestinal (GI) tract. Also, they can control the digestion of lipophilic bioactive compounds in the GI tract, while improving their bioavailability (Li et al., 2010; McClements & Li, 2010; Sun et al., 2015). In particular, nanoemulsions can inhibit bioactive compounds’ chemical and oxida- tive degradation, their large surface area can enhance lipid digestibility rates, improve the release of bioactive compounds, promote the faster formation of mixed micelles, while enhancing the bioactive compounds’ permeability across the mucus layer and epithelium cells (Cerqueira et al., 2014; Sun et al., 2015; Ting, Jiang, Ho, & Huang, 2014). None- theless, nanoemulsions present some drawbacks and their stability can be influenced by their behavior towards dehydration, temperature changes (e.g. heating, chilling and freezing-thawing) and passage through the GI tract (Cerqueira et al., 2014; Silva, Cerqueira, & Vicente, 2015a). Multilayer nanoemulsions can be used as a strategy to improve the physical stability of nanoemulsions to environmental conditions https://doi.org/10.1016/j.jff.2018.08.002 Received 30 April 2018; Received in revised form 29 July 2018; Accepted 3 August 2018 Abbreviations: DPPH, 1,1-diphenyl-2-picrylhydrazyl; DLS, dynamic light scattering; FFA, free fatty acids; GI, gastrointestinal; H d , hydrodynamic diameter; LbL, layer-by-layer; MCTs, medium chain triglycerides; O/W, oil-in-water; PBS, phosphate buffered saline; PdI, polydispersity index; SDS, sodium dodecyl sulphate; TEM, transmission electron microscopy; Zp, zeta potential ⁎ Corresponding author at: Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal. E-mail address: anapinheiro@deb.uminho.pt (A.C. Pinheiro). Journal of Functional Foods 48 (2018) 605–613 1756-4646/ © 2018 Elsevier Ltd. All rights reserved. T