In situ cross-linking of alginate during spray-drying to microencapsulate lipids in powder

Microencapsulation of emulsified lipophilic bioactive compounds in dry, cross-linked alginate microcapsules (CLAMs) is a promising strategy to facilitate their incorporation into food systems, prolong shelf life, and target delivery within the gastrointestinal tract. However, current technology to produce CLAMs requires multiple time-and energy-intensive unit operations. We developed a novel technology that streamlines CLAM production into a single unit operation by accomplishing particle formation, cross-linking, and drying during spray-drying. Spray-dried CLAMs were prepared using corn oil as the cargo, and dry basis oil loadings up to 35% (w/w) were achieved. Alginate cross-linking was verified by the insolubility of CLAMs in water and ready dissolution in sodium citrate. Volume weighted mean particle size of CLAMs increased with increasing oil content: 8.1 mu m, 11.8 mu m and 17.9 mu m for 15%, 25% and 35% oil, respectively. Spray dried CLAMs were approximately spherical, with oil droplets evenly distributed throughout each microcapsule. The size distribution of oil droplets, with average diameters ranging from approximately 200 to 300 nm, remained unchanged throughout the encapsulation process; spray drying did not induce aggregation or coalescence of oil droplets within CLAMs. CLAMs released 22-35% of oil in simulated gastric fluid (pH 1.5) and 81-93% in simulated intestinal fluid (pH 7) in 2 h, indicating that CLAMs are an enteric system. Coupled with the scalability of this novel CLAM production method, the successful encapsulation of the model lipid suggests that spray-dried CLAMs may be of commercial use for incorporating lipophilic compounds into foods. (C) 2016 Elsevier Ltd. All rights reserved.