Microencapsulation of ascorbic acid by complex coacervation: Protection and controlled release

Ascorbic acid (AA) is an efficient antioxidant that exhibits vitamin function but is naturally unstable. To overcome this problem, the objective of the present study was to improve AA microencapsulation by complex coacervation using both gelatin and gum arabic as encapsulating agents. To make the coacervation of a hydrophilic core material viable, a water-in-oil emulsion was first prepared using corn oil, a 30% solution of AA and polyglycerol polyricinoleate (PGPR 90), as the surfactant. Nine microcapsule formulations were prepared containing gelatin, gum arabic and AA at ratios of 1:1:0.5, 1:1:0.75 and 1:1:1, with 0.025, 0.05 and 0.075 g/mL of the polymer, respectively. The morphology of the freeze-dried microcapsules was analyzed by optical microscopy and scanning electronic microscopy. The water activity, hygroscopicity, solubility, particle size, encapsulation efficiency, Fourier transform infrared spectroscopy and stability of the encapsulated material were also examined. All of the microcapsule formulations were spherical, multinucleate and only slightly soluble and hygroscopic. The encapsulation efficiency was high (approximately 98%); therefore, it was possible to efficiently encapsulate AA using the double emulsion method followed by complex coacervation. The ascorbic acid was protected and more stable in the microcapsule than in solution, which suggests the possibility of controlled release under specific conditions and masking the acidic taste of AA. (C) 2013 Elsevier Ltd. All rights reserved.