Fish oil encapsulation by genipin-crosslinked complex coacervation between gelatin and different anionic polysaccharides

Herein, a combination approach of bovine bone gelatin (BBG)/anionic polysaccharide (AP) complex coacervation with genipin crosslinking was developed to successfully fabricate fish oil-loaded genipin-crosslinked BBG/AP (fish oil@BBG-genipin-AP) powders. The genipin crosslinking process promoted the formation of larger fish oil@BBG-genipin-AP particles from the BBG/AP particles and fish oil@BBG/AP particles. AP types (gum Arabic, GA; sodium alginate, SA; sodium carboxymethyl cellulose, CMC) and concentrations significantly affected the critical pH to form complex coacervated particles, the powder physicochemical properties, the powder oxidative stability, and the powder in vitro digestion. The fish oil@BBG-genipin-CMC powder at the CMC preparation concentration of 17.5 mg/mL showed the highest loading capacity value (44.3% ± 0.8%), almost the highest encapsulation efficiency value (90.9% ± 0.7%), and the highest encapsulation yield (91.3% ± 2.0%). Due to the environmental pH change, the powders changed to emulsion droplets in the gastric phase and then released free fatty acids in the small intestinal phase. The highest FFA release percentages after the gastrointestinal phase (2 h in the gastric phase and 2 h in the small intestinal phase) were dependent on both AP types and their concentrations (GA: 64.8 ± 2.9%, 62.5 mg/mL; SA: 55.0 ± 3.1%, 15 mg/mL; and CMC: 48.9 ± 1.5%, 12.5 mg/mL). GA at a concentration of 62.5 mg/mL might be the best system to prepare fish oil@gelatin-genipin-anionic polysaccharide powders for fish oil digestion. This work provided useful information to develop oil-encapsulation powders for functional foods and understand the influences of wall materials on the fabrication and properties of powder foods.