ORIGINAL PAPER Entrapment of Flaxseed Oil Within Gelatin-Gum Arabic Capsules S. Liu • N. H. Low • Michael T. Nickerson Received: 29 July 2009 / Revised: 9 February 2010 / Accepted: 16 February 2010 / Published online: 28 March 2010 Ó AOCS 2010 Abstract The aim of this study was to optimize the encapsulation of flaxseed oil within a gelatin-gum Arabic (GA) matrix via complex coacervation. The effect of homogenization rates (3,000–15,000 rpm) and total bio- polymer concentrations (1–2% w/v) on emulsion efficiency was studied in order to optimize the wall matrix. The physicochemical properties of the dried powder, and the capsule’s ability to inhibit oxidation during storage were assessed. As homogenization rates increased from 3,000 to 9,000 rpm, the structure of the capsule transitioned from a spherical mononuclear-type to irregular-shaped multinu- clear capsules. The size of the capsules and amount of non-encapsulated oil was found to increase as the total biopolymer concentration was raised from 1 to 2% (w/v). Subsequently, gelatin-GA capsules were produced with a 1:1 core-to-wall ratio at a total biopolymer concentration of 2% (w/v) and at a homogenization rate of 9,000 rpm. Formed capsules had an encapsulation efficiency of 84% and showed a protective effect against the production of primary and secondary oxidative products versus non- encapsulated oil during 25 days of room temperature storage. Keywords Flaxseed oil Á Gelatin Á Gum Arabic Á Encapsulation Á Oxidative stability Introduction Flaxseed oil offers a rich source of omega-3 fatty acids (a-linolenic acid) increasingly recognized for their role in reducing the risk of diseases and maintaining human health [1]. However, its incorporation into foods is hin- dered due to its incompatibility (i.e. lack of solubility) in the aqueous food environment and its inherent instability against oxidation [2, 3]. Various approaches have been used to increase the levels of essential fatty acids (EFAs) in the diet. Examples include: (a) the inclusion of flax- seed oils into animal feed, resulting in EFAs accumu- lating at higher levels in tissues; (b) creation of transgenic plants that are capable of synthesizing higher levels of EFAs than conventional lines; and (c) encap- sulation technology [4]. The entrapment of flaxseed oil within micron-sized particles offers a novel means to increase its compatibility in food, and at the same time improve their stability and controlled release properties for optimized bioavailability and dose delivery. The technology involves encasing or coating the core ingredient within a wall material (e.g. polysaccharides or proteins), often with cross-linking to improve mechanical integrity. Depending on the formula- tion, desirable release and functional properties (e.g. sta- bility, size, and strength) can be achieved to suit a wide range of applications. Although encapsulation technology is commercially available, significant hurdles still limit its widespread use in food. The coacervation process involves the electrostatic attraction between two biopolymers of opposing charges, and typically occurs over a narrow pH range. Gelatin-gum Arabic (GA) based capsules have been previously studied for a variety of applications. Yeo et al. [5] investigated the effect of polyion concentration, homogenization rates, and S. Liu Á N. H. Low Á M. T. Nickerson (&) Department of Food and Bioproduct Sciences, University of Saskatchewan, 51 Campus Dr., Saskatoon, SK S7N 5A8, Canada e-mail: Michael.Nickerson@usask.ca 123 J Am Oil Chem Soc (2010) 87:809–815 DOI 10.1007/s11746-010-1560-7