Oxidative stability of microencapsulated fish oil powders stabilized by blends of chitosan, modified starch, and glucose.

Various indices of lipid oxidation were used to assess the oxidative stability of microencapsulated fish oil powders prepared from tuna oil-in-water emulsions (pH 4.9 or 6.0) containing chitosan, an emulsifying starch, and glucose. There were good agreements among the induction period for oxidation under accelerated conditions (80 degrees C, 5 bar oxygen), the development of oxidation volatile markers from fish oil (namely, propanal, 1-penten-3-ol, 1-penten-3-one, 2,4-(Z,E)-heptadienal, and 2,4-(E,E)-heptadienal), and the loss of eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) over four weeks of storage at 25 degrees C. All indices of oxidation showed that powders prepared from emulsions at pH 6.0 were more stable to oxidation than corresponding formulations at pH 4.9. It is suggested that the increased electrostatic interactions between the chitosan and emulsifying starch at the higher pH contributed to the increased stability of the microcapsule powders.