Effect of layer (calcium phosphateechitosan)-by-layer (mesquite gum) matrix on carotenoids-in-water-emulsion properties Eristeo García-M  arquez a , Ang  elica Rom  an-Guerrero b , Francisco Cruz-Sosa b , Consuelo Lobato-Calleros c , Jesús  Alvarez-Ramírez d , E. Jaime Vernon-Carter d , Hugo Espinosa-Andrews a, * a Unidad de Tecnología Alimentaria, Centro de Investigaci on y Asistencia en Tecnología y Dise~ no del Estado de Jalisco, A.C. Av. Normalistas 800, Guadalajara, Jalisco 44270, Mexico b Departamento de Biotecnología, Universidad Aut onoma Metropolitana Unidad Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, M exico, D.F. 09340, Mexico c Departamento de Preparatoria Agrícola, Universidad Aut onoma Chapingo, Km 38.5 Carretera M exico-Texcoco, 56230 Texcoco, Mexico d Departamento de Ingeniería de Procesos e Hidr aulica, Universidad Aut onoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, M exico, D.F. 09340, Mexico article info Article history: Received 12 May 2014 Accepted 4 July 2014 Available online 17 July 2014 Keywords: Layer-by-layer emulsion Potentiometric titration Turbidity Zeta-potential Viscoelastic properties Carotenoid degradation kinetics abstract Layer-by-layer calcium phosphate (CP)echitosan (Ch)/mesquite gum (MG) matrixes were designed for protecting and stabilizing red chili oleoresin-in-water emulsions. Potentiometric titration, turbidity and z-potential measurements were used for establishing the interaction windows for obtaining CPeCh complexes. The CPeCh mass ratio of 1.24 showed the maximum soluble complex formation and a positive charge (~18.5 mV) for allow the interaction with MG. Then, red chili oleoresin-in-water emul- sions were formed by a layer-by-layer deposition of MG/CPeCh complexes (C/W RMG/CPeCh ). The results show that high mass ratio of MG was required to form a dense interfacial layer to improve the stability of the system. The droplet size distribution remained unchanged up to 720 h. Rheological measurements of C/W RMG/CPeCh indicate that both, the storage (G 0 ) and loss (G 00 ) moduli showed increasing values with frequency (~0.4e11.0 Hz) independently of shear strain applied (1, 5,10%), attributed to the formation of MG/CPeCh interlinked network in the continuous phase. The emulsion providing best stability and protection against carotenoid degradation was that made with CPeCh mass ratio of 1.24 and MG/CPeCh mass ratio of 10. The mean half-time life of the C/W 10 was 502 days compared to 0.24 days for the free unprotected carotenoids. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Natural polysaccharides are increasingly used in the food in- dustry as additives for encapsulation purposes. Emulsions, lipo- somes and complex matrices are examples of soft material where polysaccharides are used for protecting bioactive materials from the effects of light, oxygen and other adverse environmental con- ditions. The action of polysaccharides relies on the modification of microstructure, having an important impact on the stability and rheological properties of commercial products. Given the diversity of structure and properties of natural polysaccharides, physical and chemical combinations are commonly used for taking advantage of the desired characteristics of individual components (Ramírez- Santiago, Lobato-Calleros, Espinosa-Andrews, & Vernon-Carter, 2012). The importance of the microstructure of combined (e.g., bi-layers, blends, coacervates, etc.) polysaccharides has been recognized and extensively studied in the recent decade (Chen, Moschakis, & Nelson, 2004; Chen, Moschakis, & Pugnaloni, 2006; Espinosa-Andrews, Sandoval-Castilla, V azquez-Torres, Vernon- Carter, & Lobato-Calleros, 2010; Leal-Calderon, Thivilliers, & Schmitt, 2007; Moschakis, Murray, & Biliaredis, 2010; Moschakis, Murray, & Dickinson, 2006; Viana-Filho, Oliveira-Petkowicz, & Meira-Silveira, 2013). The use of chitosan (Ch) for the encapsulation of active components has gained interest in the last years due to its mucous adhesiveness, non-toxicity, biocompatibility and biode- gradability (Harris, Lecumberri, Mateos-Aparicio, Mengíbar, & Heras, 2011). Ch is a heterogenous binary polymer consisting of * Corresponding author. E-mail addresses: hespinosa@ciatej.mx, andrewshugo@hotmail.com (H. Espinosa-Andrews). Contents lists available at ScienceDirect Food Hydrocolloids journal homepage: www.elsevier.com/locate/foodhyd http://dx.doi.org/10.1016/j.foodhyd.2014.07.005 0268-005X/© 2014 Elsevier Ltd. All rights reserved. Food Hydrocolloids 43 (2015) 451e458