Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem Short communication Preparation of donut-shaped starch microparticles by aqueous-alcoholic treatment Yousof Farrag a , Constanza Sabando b , Saddys Rodríguez-Llamazares b, ⁎ , Rebeca Bouza a , Claudio Rojas b , Luís Barral a a Universidade da Coruña, Grupo de Polímeros, Departamento de Física, Escuela Universitaria Politécnica, Serantes, Avda. 19 de febrero s/n, 15471 Ferrol, Spain b Centro de Investigación de Polímeros Avanzados, CIPA, Avenida Collao 1202, Edificio de Laboratorios, Concepción, Chile ARTICLE INFO Keywords: Microparticle Starch Donut-shape Microcarriers ABSTRACT A simple method for producing donut-shaped starch microparticles by adding ethanol to a heated aqueous slurry of corn starch is presented. The obtained microparticles were analysed by SEM, XRD and DSC. The average size of microparticles was 14.1 ± 0.3 μm with holes of an average size of 4.6 ± 0.2 μm. The crystalline arrange- ment of the microparticles was of a V-type single helix. The change in crystallinity from A-type of the starch granules to a more open structure, where water molecules could penetrate easier within the microparticles, substantially increased their solubility and swelling power. The microparticles exhibited a higher gelatinization temperature and a lower gelatinization enthalpy than did the starch granules. The donut-shaped microparticles were stable for more than 18 months and can be used as a carrier of an active compound or as a filler in bioplastics. 1. Introduction Starch is a natural polymer of glucose that is widely available, biodegradable and biocompatible. Depending on the botanical source, the starch granules are typically of many micrometres in size and of different shapes. There are several strategies to increase the surface area of starch granules and thereby their processability and perfor- mance. For example, in the acid hydrolysis treatment the particle size of starch is reduced and its degree of crystallinity is increased, which leads to a decrease of the swelling power and pasting temperature and retards the development of viscosity (Gonçalves, Noreña, da Silveira, & Brandelli, 2014). Starch structures with a high area to vo- lume ratio, i.e. micro/nanoparticles, have been used as a carrier to modulate the release of active compounds (El-Feky, El-Rafie, El-Sheikh, El-Naggar, & Hebeish, 2015). The size and the shape of the micro/na- noparticles, as well as their properties and release characteristics, de- pend on the preparation method (Xie, Pollet, Halley, & Avérous, 2013). A granular cold water-soluble starch has been used as a solid bio- degradable matrix to encapsulate substances, such as ethylene (Shi, Fu, Tan, Huang, & Zhang, 2017), atrazine (Chen & Jane, 1995), and fatty acids (Lay Ma, Floros, & Ziegler, 2011). These microparticles are gen- erally obtained by an alcoholic-alkaline treatment, where the sodium hydroxide disrupts the intermolecular hydrogen bonds of starch mac- romolecules, while ethanol inhibits the swelling of the granules (Chen & Jane, 1994). Although the overall integrity of the granules is preserved, the starch granules are completely deformed and the size is increased after the treatment. In this communication, a simple and novel method for the pre- paration of donut-shaped microparticles is described, in which heated starch slurry is precipitated by addition of ethanol. The morphology, structure, thermal and swelling properties of the microparticles were studied. The produced microparticles are intended to be used mainly as a carrier of active compounds or filler for bioplastics; both uses could be combined for active food packaging applications. 2. Materials and methods 2.1. Materials and reagents Corn starch, composed of 25% amylose, was supplied by Roquette Freres S. A. (France). Ethanol was purchased from Scharlau (Spain). 2.2. Preparation of starch microparticles The microparticles preparation from corn starch granules was per- formed according to the method proposed by Ma, Jian, Chang, and Yu (2008) with modifications. In short, 8 g of starch were added to 150 ml of Milli-Q water. The mixture was heated at 66 °C, below the http://dx.doi.org/10.1016/j.foodchem.2017.10.147 Received 1 June 2017; Received in revised form 11 October 2017; Accepted 31 October 2017 ⁎ Corresponding author at: Centro de Investigación de Polímeros Avanzados (CIPA), Avenida Collao 1202, Edificio de Laboratorios CIPA, 4051381 Concepción, Chile. E-mail address: s.rodriguez@cipachile.cl (S. Rodríguez-Llamazares). Food Chemistry 246 (2018) 1–5 0308-8146/ © 2017 Elsevier Ltd. All rights reserved. MARK