Encapsulation of Haematococcus pluvialis using chitosan for astaxanthin stability enhancement

Astaxanthin is receiving commercial interest due to its use as a preferred pigment in aquaculture feeds. Its antioxidant activity is approximately 100 times higher than that of beta-tocopherol, and can be used as a potential agent against cancer. Astaxanthin can easily be degraded by thermal or oxidative processes during the manufacture and storage. In this study, astaxanthin and its biological activity were protected against oxidative environmental conditions by encapsulating the homogenized cells in chitosan. Haematococcus pluvialis were formed into beads, which were then coated with 5 layers of chitosan film, resulting in chitosan-algae capsules that have a mean diameter of 0.43 cm and the total film thickness of approximately 100 pm. No significant loss in the amount of astaxanthin content in H. pluvialis was found due to the process of encapsulation. However, approximately 3% loss of antioxidant activity of the H. pluvialis was observed after encapsulation. The results of stability under different storage conditions showed that although encapsulation caused 3% loss of antioxidant activity, the longer term stability of the dried algae biomass, beads, and capsules indicated that encapsulation of H. pluvailis in chitosan film was capable of protecting the algae cells from oxidative stresses. (C) 2007 Elsevier Ltd. All rights reserved.