Preparation and characterisation of octenyl succinate starch as a delivery carrier for bioactive food components Xueyu Wang a , Xiaoxi Li a , Ling Chen a,⇑ , Fengwei Xie b , Long Yu a , Bing Li a a Ministry of Education Engineering Research Center of Starch & Protein Processing, College of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510640, China b Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Qld 4072, Australia article info Article history: Received 3 August 2010 Received in revised form 25 October 2010 Accepted 1 December 2010 Available online 7 December 2010 Keywords: Octenyl succinate starch Esterification Bioactive food components Delivery carrier abstract The octenyl succinic anhydride (OSA) modified corn starch (OSAS) was synthesised with different degrees of substitution (DS) and the influences of three factors namely OSA/starch ratio, reaction temperature, and reaction time on the DS of OSAS were studied by response surface methodology (RSM). As a delivery carrier material, the characteristics of OSAS were investigated. The resistant starch (RS) content of OSAS was increased with increasing DS, indicating the improvement of colon-targeting property. The swelling ratio (SR) of the OSAS in simulated gastrointestinal fluids was higher than that of native starch and its hydrophilicity was decreased with increasing DS. For in vitro release study, the percentage of released bioactive components was less than 7% within the first 8 h and close to 100% over a period of 36 h when the DS was 0.60. These results demonstrate that OSAS can be a potential carrier for colon-targeted deliv- ery of bioactive food components. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The incorporation of bioactive components in food provides a simple way to develop novel functional foods, which could have physiological benefits or reduce risk of diseases. This approach has received much attention in recent years from scientific com- munities, food manufacturers and consumers, and has experienced an intensive development in recent years (Chen, Remondetto, & Subirade, 2006). However, the work is still challenging due to the difficulty in the accurate control of release of bioactive food com- ponents in the body digestive system. It is important to overcome the chemical and enzymatic degradation in the upper gastrointes- tinal tract, which limits the activity and potential health benefits of nutraceutical molecules (Bell, 2001). Besides, bioactive compo- nents need to be delivered to specific destinations in the gut for full functionality and health effects (deFonseka & Kaunitz, 2009; Erickson & Hubbard, 2009). Most encapsulation approaches are based on pH value and time-dependent release principles. How- ever, these systems may release their contents in the upper gastro- intestinal tract due to the unpredictable variations of pH value and intestinal transit time. As a result, it is crucial to develop controlled release carriers for bioactive food components (de Vos, Faas, Spasojevic, & Sikkema, 2010). There has already been increasing interests in oral colon-targeted drug delivery systems. This is because colon has relatively low activity of proteolytic enzymes and good bioavailability, and it is an ideally suited for protein and peptide absorption (Lee & Mukkerjee, 2002). The matrix mol- ecules of carriers need to be able to withstand the environmental changes in the upper gastrointestinal tract but to be rapidly degraded by the enzymes produced by the colonic microbiota. However, this model has not yet been fully employed in food science. Currently, the most popular controlled release carrier materials are starch (Freire, Podczeck, Veiga, & Sousa, 2009), protein (Chen et al., 2006), chitosan (Kosaraju, 2005), and sodium alginate (de Vos et al., 2010). Starch, as a natural polymer, received much atten- tion in this area due to its abundant availability, low-cost, biode- gradability, biocompatibility, non-toxicity, and so on. Moreover, starch itself is a physiologically active component. By appropriate modification, it can inhibit colon cancer, lower cholesterol, and reduce cardiovascular disease (Martinez-Flores, Kil Chang, Martinez-Bustos, & Sgarbieri, 2004). However, in controlled release systems, many bioactive components based on native starch are released too fast. The multi-hydroxyl structure of starch makes it highly hydrophilic, which could result in the loss of embedded bioactive components in the foregut. Therefore, native starch is normally unsuitable as the controlled release carrier material for bioactive food components. Typically, starch derivatives are more resistant to enzymatic lysis than native starch. By modifying starch, some fractions of starch may become indigestible in the small intestine, which is 0308-8146/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2010.12.006 ⇑ Corresponding author. Tel./fax: +86 20 8711 3252. E-mail address: felchen@scut.edu.cn (L. Chen). Food Chemistry 126 (2011) 1218–1225 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem