Microencapsulation of stearidonic acid soybean oil in Maillard reaction-modified complex coacervates Ebenezer A. Ifeduba, Casimir C. Akoh ⇑ Department of Food Science and Technology, University of Georgia, Athens, GA 30602-2610, USA article info Article history: Received 22 June 2015 Received in revised form 9 November 2015 Accepted 2 December 2015 Available online 7 December 2015 Keywords: Microencapsulation Complex coacervation Stearidonic acid soybean oil Omega-3 oils Maillard reaction products Antioxidant capacity Oxidative stability abstract The antioxidant capacity of Maillard reaction (MR)–modified gelatin (GE)–gum arabic (GA) coacervates was optimized to produce microcapsules with superior oxidative stability compared to the unmodified control. MR was used to crosslink GE and GA, with or without maltodextrin (MD), to produce anti- oxidative Maillard reaction products (MRP) which was used to encapsulate stearidonic acid soybean oil (SDASO) by complex coacervation. Biopolymer blends (GE–GA [1:1, w/w] or GE–GA–MD [2:2:1, w/w/w]) were crosslinked by dry-heating at 80 °C for 4, 8, or 16 h. Relationships between the extent of browning, Trolox equivalent antioxidant capacity (TEAC), and the total oxidation (TOTOX) of encapsu- lated SDASO were fitted to quadratic models. The [GE–GA–MD] blends exhibited higher browning rates and TEAC values than corresponding [GE–GA] blends. Depending on the type of biopolymer blend and dry-heating time, TOTOX values of SDASO in MRP-derived microcapsules were 29–87% lower than that of the non-crosslinked control after 30 days of storage. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Complex coacervation is a phase separation phenomena that occurs when oppositely-charged hydrocolloids interact non- covalently to form a liquid electro-neutral complex known as a coacervate (Bungenberg de Jong, 1965). The formation of coacer- vates may be initiated by adjusting the pH, temperature, or by dilu- tion of the bulk sol. When complex coacervation is elicited in the presence of dispersed oil droplets, encapsulation occurs by deposi- tion of a coacervate film around oil droplet(s). Subsequent cooling transforms the coacervate film to a hydrogel and forms microcap- sules with high payloads and controlled-release capabilities (Gouin, 2004). Since encapsulation by coacervation is driven by non-covalent interactions, a crosslinking agent must be added to stabilize the capsular wall. Microencapsulation of lipophilic sub- stances by complex coacervation was first described by Green and Schleicher (1957) who used porcine gelatin (GE) and gum ara- bic (GA) as the encapsulating biopolymers. Since then many encap- sulation studies based on complex coacervation have been reported, most of which focused on improving the acceptability and performance of encapsulating biopolymers for food applica- tions. Consequently, a wide collection of proteins, polysaccharides, and blends thereof, have been identified as potential candidates for encapsulation of food ingredients by coacervation on commercial scale (Thies, 2012). Although complex coacervation is a promising encapsulation technique, application by the food industry was ini- tially limited by perceptions of high process cost and toxicity asso- ciated with the use of chemical cross-linking agents, such as gluteraldehyde or formaldehyde, as process aids. Food industry interest has increased due to reports demonstrating that poten- tially harmful chemical crosslinking agents can be replaced by enzyme-induced crosslinking with transglutaminase (TG; amine c-glutamyl transferase, EC 2.3.2.13) (Thies, 2012), but long pro- cessing times and negative consumer perception of TG (controver- sially dubbed ‘‘meat glue”) are issues that need to be addressed. Research interest in complex coacervation technique continue to be high as studies demonstrating that stable microcapsules loaded with high-value core materials, such as omega-3 oils, can be produced. In a recent study, we found that the encapsulation of stearidonic acid soybean oil (SDASO) in complex coacervates based on a Maillard reaction product (MRP) of GE and GA yielded microcapsules that displayed higher colloidal, thermal, and oxidative stabilities compared to microcapsules based on non- or TG-crosslinked [GE–GA] complex coacervates (Ifeduba & Akoh, 2015). The use of Maillard reaction (MR) to crosslink GE and GA and produce anti-oxidative MRPs prior to encapsulation of omega-3 oil by coacervation was demonstrated. However, there is need to improve the antioxidant capacity of the MR-modified [GE–GA] complex coacervate since the antioxidant effect of MRPs http://dx.doi.org/10.1016/j.foodchem.2015.12.011 0308-8146/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: cakoh@uga.edu (C.C. Akoh). Food Chemistry 199 (2016) 524–532 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem