Carbohydrate Polymers 103 (2014) 234–243 Contents lists available at ScienceDirect Carbohydrate Polymers jo u r n al homep age: www.elsevier.com/locate/carbpol Inﬂuence of glucan structure on the swelling and leaching properties of starch microparticles Nicolas Bordenave 1 , Srinivas Janaswamy, Yuan Yao ∗ Department of Food Science, Purdue University, 745 Agriculture Mall Dr., West Lafayette, IN 47907, United States a r t i c l e i n f o Article history: Received 30 April 2013 Received in revised form 21 November 2013 Accepted 25 November 2013 Available online 4 December 2013 Keywords: Starch Microparticle Swelling Leaching Crystallinity Response surface method Molecular weight a b s t r a c t Microparticles were made by a water-in-oil emulsion technique from acid-hydrolyzed and debranched normal, waxy and high-amylose corn starches. The starches prepared had a weight-average molecu- lar weight (M w ) ranging 3.6 × 10 7 –2.5 × 10 4 , a polydispersity ranging 1.16–9.16, an apparent amylose content ranging 2.84–100%. These microparticles exhibited crystallinity ranging 4.41–22.84%, swelling power ranging 2.45–7.84 and percentage of leaching ranging 1.72–74.91%. Swelling power in water (R 2 = 0.86) and percentage of leaching in water (R 2 = 0.89) were modeled by a response surface method, using the following parameters: M w , polydispersity, apparent amylose content and crystallinity of starch in microparticles. Overall, this study showed the key parameters for controlling the behavior of starch microparticles were related to the cohesiveness of the three-dimensional network, particularly through the retrogradation of starch polymers, the formation of crystallites and junctions zones. Such micro- particles could be used for designing economical and biocompatible delivery systems of compounds for food, drug, or other applications. © 2013 Elsevier Ltd. All rights reserved. 1. Introduction Over the last decades, polymer-based delivery systems have gained considerable interest. These systems, commonly based on the formation of hydrogels from synthetic or natural polymer, have been extensively studied and developed (Hamidi, Azadi, & Raﬁei, 2008). On the one hand, the preparation of synthetic polymers is often well understood and controlled, leading to “smart” mate- rials with ﬁnely tuned characteristics. However, these polymers cannot be guaranteed for innocuousness, because of potential reac- tants remaining from their synthesis or products resulting from the polymer enteric degradation (Goddard & Hotchkiss, 2007). More- over, these systems rely on the use of non-renewable resources. Biopolymers also exhibit disadvantages that must be overcome for delivery applications (e.g. variability of their physicochemical characteristics depending on their source). However, biopolymers that can readily make hydrogels (e.g. chitosan, carrageenan and starch) are well known for their biocompatibility and non-toxicity (Chandra & Rustgi, 1998; Reis & Cunha, 2001; Varshosaz, 2007). In this perspective, starch has been widely studied, after modiﬁcations or in combinations with other polymers (Calinescu, Mulhbacher, ∗ Corresponding author. Tel.: +1 765 494 6317; fax: +1 765 494 7953. E-mail address: yao1@purdue.edu (Y. Yao). 1 Present address: PepsiCo Global R&D, 617 W Main Street, Barrington, IL 60010, United States. Nadeau, Fairbrother, & Mateescu, 2005; Elvira, Mano, San Román, & Reis, 2002; Fransén, Björk, & Edsman, 2008; Oechslein, Fricker, & Kissel, 1996; Onofre, Wang, & Mauromoustakos, 2009; Rahmouni et al., 2003; Tuovinen et al., 2004). In the case of in vivo delivery of bioactive compounds, whether the carriers are pre-hydrated hydrogels or hydrogels formed in situ from dry particles, these systems rely on the capability of the polymer network to swell upon water absorption and eventu- ally to disintegrate, in order to let active compounds be released and diffuse (Peppas & Brannon-Peppas, 2001). This disintegration can also be achieved via digestion of starch in the gastrointestinal tract: swelling and leaching of the loaded particles are here crucial parameters to tune the kinetics of degradation, because they will affect the accessibility of glucan chains to the digestive enzyme -amylase (Cristina Freire, Fertig, Podczeck, Veiga, & Sousa, 2009). Achieving a wide range of swelling and leaching characteristics can then lead to controlled delivery proﬁles of target compounds. Thus, this study aims to show that microparticles having potential for simple delivery systems can be prepared from starch only, by taking advantage of starch molecular properties and characteristics. Starch is composed of amylopectin and amylose, two high molecular-weight, polydisperse (1,4)--d-glucans. Amylopectin is highly branched through (1,6)- linkages (M w ∼5 × 10 7 –5 × 10 8 , average chain length ∼20–30 units) and soluble in water as an iso- lated polymer (as opposed to native state in granular form), and amylose is linear or slightly branched (M w ∼10 5 –10 6 , average chain length ∼10 2 –10 3 units), nearly insoluble in water as an isolated 0144-8617/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.carbpol.2013.11.031