Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem Thermodynamic criteria analysis for the use of taro starch spherical aggregates as microencapsulant matrix Javier D. Hoyos-Leyva a , Luis A. Bello-Pérez a, ⁎ , J. Alvarez-Ramirez b a Instituto Politécnico Nacional, CEPROBI, Yautepec, Morelos, Mexico b Departamento de Ingeniería de Procesos e Hidráulica, Universidad Autónoma Metropolitana-Iztapalapa, Iztapalapa, CDMX 09340, Mexico ARTICLE INFO Keywords: Starch Sorption isotherm Enthalpy Entropy Diffusion ABSTRACT Spherical aggregates can be obtained from taro starch by spray-drying without using bonding agents. Accurate information about thermal issues of spherical aggregates can provide valuable information for assessing the application as encapsulant. Spherical aggregates of taro starch were obtained by spray-drying and analyzed using dynamic vapour sorption. The use of the Guggenheim, Anderson and de Boer (GAB) model indicated a Type II isotherm pattern with weaker interactions in the multilayer region. Differential enthalpy and entropy estimates reflected a mesoporous microstructure, implying that energetic mechanisms dominate over transport mechanisms in the sorption process. The limitation by energetic mechanisms was corroborated with enthalpy- entropy compensation estimates. The diffusivity coefficient was of the order of 10 -8 m 2 ·s -1 , which is in line with results obtained for common materials used for encapsulation purposes. The thermodynamic properties and the lack of a bonding agent indicated the viability of spherical aggregates of taro starch for encapsulation of bio- compounds. 1. Introduction Starch spherical aggregates obtained from diverse botanical sources have been considered as suitable structures for microencapsulation purposes. Zhao and Whistler (1994) found that amaranth and small wheat and corn starch granules can lead to spherical aggregates during spray-drying. However, the formation of spherical aggregates required the addition of bonding agents, such as gums and proteins. Tari et al. (2003) studied the ability of small sized starch granules from amaranth (Amaranthus paniculatus L.), quinoa (Chenopodium quinoa L.), rice (Oryza sativa L.) and colocasia (Colocasia esculenta L.) in the presence of polysaccharide bonding agents (gum Arabic, carboxymethyl cellulose and carrageenan) to microencapsulate vanilla as a model compound. It was found that amylose content was negatively correlated with the extent of entrapment of vanillin held within the spherical aggregates. Beirão-Da-Costa, Duarte, Moldão-Martins, & Beirão-da-Costa (2011) explored the effect of the presence of bonding agents (CMC and/or gelatin), and of solids content, on the physical characteristics of sphe- rical aggregates from rice starch. Interestingly, it was found that the concentration of the bonding agent did not significantly affect the porosity of spherical aggregates. Gonzalez-Soto, de la Vega, García- Suarez, Agama-Acevedo, and Bello-Pérez (2011) reported that taro starch had the ability to form spherical aggregates without the addition of bonding agents. Notably, Gonzalez-Soto et al. (2011) only reported the method for obtaining spherical aggregates from taro starch. In fact, these authors only reported the formation of spherical aggregates as a peculiarity of taro starch, without further exploring potential applica- tions of such structures. However, the peculiarity of taro starch sphe- rical aggregates indicates that it could be used as wall material in en- capsulation of substances. In many instances, studies on wall materials rely on empirical results with trial-and-error strategies, while focussing mainly on the encapsulation of model biocompounds and the de- termination of underlying parameters (e.g., encapsulation efficiency, microcapsules stability). However, stability issues of materials intended for microencapsulation purposes are rarely considered. Rheological and thermal characteristics of the wall materials can be assessed before establishing their potential use as raw materials for encapsulation of biocompounds. The thermal properties commonly studied are glass transition temperature and activation energy. Activation energy (E a ) is a thermal property that can be used as a cri- terion for establishing the suitability of polymers as wall materials for microencapsulation by spray-drying (Anandharamakrishnan & Ishwarya, 2015). High activation energy (∼25.0–30.0 kJ·mol -1 ) of wall materials is desirable to obtain an effective protection of the core during spray-drying (Pérez-Alonso, Báez-González, Beristain, Vernon- Carter, & Vizcarra-Mendoza, 2003). The activation energy can be https://doi.org/10.1016/j.foodchem.2018.03.130 Received 18 December 2017; Received in revised form 19 March 2018; Accepted 28 March 2018 ⁎ Corresponding author. E-mail address: labellop@ipn.mx (L.A. Bello-Pérez). Food Chemistry 259 (2018) 175–180 Available online 29 March 2018 0308-8146/ © 2018 Elsevier Ltd. All rights reserved. T