Encapsulation of beta-carotene-loaded oil droplets in caseinate/alginate microparticles: Enhancement of carotenoid stability and bioaccessibility

b-carotene was encapsulated in biopolymer microparticles formed by electrostatic complexation to improve its water-solubility, chemical stability, and bioavailability characteristics. The beta-carotene-loaded microparticles had a particle size (1.87 +/- 0.03 mu m) larger than that of caseinate emulsions (0.48 +/- 0.01 mu m) (P < .05). Microparticles were stable to aggregation over a wide pH range (3-7) and at high salt levels (0-1000 mM NaCl), and protected beta-carotene from degradation during storage. For instance, around 32% carotenoid was retained after 42 days storage at 25 degrees C in the microparticles, whereas <10% was retained in the emulsions. An in vitro digestion experiment showed that the beta-carotene in microparticles had a higher bioaccessibility and chemical stability (67.57 +/- 2.72% and 80.03 +/- 1.95%, respectively) than in emulsions (30.03 +/- 1.87% and 70.87 +/- 1.52%, respectively) (P < .05). These results may facilitate the design of nutraceutical delivery systems for application in food, supplement, and pharmaceutical products.