Contents lists available at ScienceDirect Journal of CO 2 Utilization journal homepage: www.elsevier.com/locate/jcou Study of chia oil microencapsulation in soy protein microparticles using supercritical Co 2 -assisted impregnation Nicolas Gañan a,c , María Gabriela Bordón b,c , Pablo D. Ribotta b,c , Agustín González a,d, * a Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada (IPQA-CONICET), Av. Vélez Sarsfield 1611, Ciudad Universitaria, Córdoba, Argentina b Instituto de Ciencia y Tecnología de los Alimentos Córdoba (ICyTAC-CONICET), Juan Filloy s/n, Ciudad Universitaria, Córdoba, Argentina c Instituto de Ciencia y Tecnología de los Alimentos (ICTA-FCEFyN-UNC), Av. Velez Sarsfield 1611, Ciudad Universitaria, Córdoba, Argentina d Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Medina Allende y Haya de la Torre, Ciudad Universitaria, Córdoba, Argentina ARTICLE INFO Keywords: Chia oil Soy protein Supercritical impregnation Microparticles Oxidative stability ABSTRACT Microencapsulation of chia oil in soy protein microparticles was achieved using supercritical CO 2 -assisted im- pregnation, an alternative green technology. The effect of the process variables on retention and encapsulation efficiencies was studied. The characterization of the chia oil-loaded microparticles showed excellent en- capsulation efficiency, a spherical shape with some depressions but without pores or fissures, sizes between 1 and 10 μm and homogeneous oil distribution. The hydroperoxide values and fatty acid profile indicated that the microencapsulation process did not affect the chemical quality of the oil. In addition, a study of the influence of storage time showed excellent oxidative stability for microencapsulated samples compared to free oils, with the microparticles providing a remarkable protective effect that enhances the useful life of the product. It was determined that 95.69 ± 4.28 % of the oil was released under gastro-intestinal conditions, mainly in the in- testinal step, remaining available for absorption. 1. Introduction The consumption of polyunsaturated fatty acid-rich oils, such as chia oil, provides numerous health benefits. Increasing knowledge about the influence on health of these compounds, grouped in the omega-9, omega-6 and omega-3 series, has increased consumption of these special oils. A diet rich in these compounds decreases the risk of many diseases, especially cardiovascular diseases, cancer and metabolic syndrome [1]. Chia seeds, with 32–39 % of oil, are the richest source of omega-3 fatty acids among vegetable sources (61–70 %) [2], and the unusual proportions of polyunsaturated fatty acids present in this oil are responsible for its great nutritional and therapeutic value. Food containing high amounts of unsaturated fatty acids is bene- ficial from a nutritional point of view; however, when these oils are exposed to environmental factors such as air, light and temperature, they become oxidized, altering their chemical and organoleptic quality, leading to a shorter shelf life. The incorporation of these oils into processed foods is also limited due to processing conditions such as baking, mixing and long storage periods [3]. For this reason, it is vital to develop technologies capable of protecting the oil, preventing oxi- dation and maintaining its nutritional and organoleptic characteristics over time. One competent technology to prevent oil oxidation and keep its nutritional characteristics intact is its microencapsulation in solid matrices [4]. This process converts the oil into a powder, which can be easily manipulated and used for the elaboration of nutraceutical pro- ducts and/or functional foods [5]. The use of vegetable proteins as a wall material is being widely developed, particularly in the fields of nutrition, pharmaceuticals, and cosmetics. Its excellent surfactant properties, high stabilizing activity, and a tendency to form a fine, dense network make this type of mate- rials very suitable for the microencapsulation of lipid compounds [6]. Soy protein isolate (SPI) has shown advantages due to its exceptional properties for forming films; at the same time, it presents good barrier properties to oxygen, aromas, and lipids under intermediate humidity conditions [7,8]. This type of protein also produces softer and more flexible coatings than proteins from other plant sources [9]. There are different methods for the microencapsulation of vegetable oils reported in the literature, such as spray-drying, freeze-drying, https://doi.org/10.1016/j.jcou.2020.101221 Received 15 January 2020; Received in revised form 8 May 2020; Accepted 14 June 2020 ⁎ Corresponding author at: Medina Allende and Haya de la Torre, Ciudad Universitaria, Córdoba, 5000, Argentina. E-mail addresses: nicolas.ganan@unc.edu.ar (N. Gañan), gabrielabordon90@gmail.com (M.G. Bordón), pribotta@agro.unc.edu.ar (P.D. Ribotta), agustingonzalez@unc.edu.ar (A. González). Journal of CO₂ Utilization 40 (2020) 101221 2212-9820/ © 2020 Elsevier Ltd. All rights reserved. T