Stability of Fish Oil in Calcium Alginate Microcapsules Cross-Linked by In Situ Internal Gelation During Spray Drying

Microencapsulating bioactive compounds, such as polyunsaturated fatty acids (PUFA), in dry cross-linked alginate serves to enhance their shelf life, mask unwanted flavors and odors, facilitate their incorporation into food products, and provide an intestinal release mechanism. Alginate microencapsulation is challenging to implement at industrial scale, but a recently developed process provides scalability by accomplishing alginate cross-linking in situ during spray drying. This study investigated how formulation variables affect the oxidative stability of fish oil in cross-linked alginate microcapsules (CLAMs) prepared via this industrially scalable process. Storage stability of PUFA from fish oil was prolonged by microencapsulation in CLAMs, relative to nonencapsulated fish oil. Neither the choice of emulsifier (Tween 80 or whey protein isolate) nor the extent of alginate cross-linking influenced the duration of storage stability of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, the retention of EPA and DHA during spray drying was significantly lower for CLAMs prepared with Tween 80. The addition of n-octenyl succinic anhydride (OSA) modified starch into spray-drying formulations improved the storage stability of microencapsulated fish oil. With increasing OSA-starch content in CLAMs, surface oil content decreased, particle size and powder yield increased, and PUFA storage stability increased. Despite OSA-starch being the majority component, OSA-starch CLAMs exhibited gastrointestinal release properties more akin to CLAMs than control OSA-starch microcapsules. OSA-starch CLAMs retained fish oil cargo in simulated gastric fluid and released it in simulated intestinal fluid, while OSA-starch microcapsules completely released cargo in either fluid. Overall, OSA-starch CLAMs show promise as an industrial-scale system for stabilizing PUFA while providing an enteric delivery mechanism.