Formation and stability of shark liver oil loaded chitosan/calcium alginate capsules

Calcium alginate capsules containing shark liver oil were prepared by ionotropic gelation of alginate solutions. Since the capsules were permeable to the oil, they were coated with a membrane of chitosan-alginate polyelectrolyte complex to reduce permeability. Encapsulation efficiencies (expressed as the percentage of shark liver oil entrapped) greater than 87% (w/w) were obtained by using 6% (w/v) alginate solution. The oil content in the capsules was higher than 65% (w/w) when the oil was dispersed in the alginate solution at 10% (v/v) or more. However, at the level of 15 or 20% (v/v) the oil was exuded after 48 h. Capsules were degraded in vitro by enzymes, with lipase being more effective than pancreatine. No release of oil from the capsules up to 4 h at pH 1.2 was observed, but after 4 h the capsules became very fragile when they were immersed in buffer solution at pH 7.4.