Improving functional properties of Spirulina protein by covalent conjugation followed by complex coacervation processes

Two stage complexation processes, i.e., covalent conjugation followed by complex coacervation processes were used to improve functional properties of Spirulina protein. Conjugates of Spirulina protein concentrate (SPC)-maltodextrin (MD) were produced via wet-route Maillard reaction and they were coacervated with carrageenan (CG). The complex coacervates of mixture of unconjugated SPC and MD with CG was used as benchmark. (SPC-MD conjugate)-CG coacervate and (SPC-MD mixture)-CG coacervate were used as shell material to encapsulate oxidation sensitive canola oil. The optimum conditions for the complex coacervation were found at pH 3.0 and ratio of conjugate- or mixture-to-CG ratio of 24:1 (w/w). Spray-dried microcapsules of canola oil produced using (SPC-MD conjugate)-CG coacervates exhibited lower surface oil content (1.52%), higher encapsulation efficiency (92.5%), and smaller particle size (D50=7.66 µm) compared to those produced using mixture-based coacervates as shell materials. The microcapsules produced using conjugate-based coacervates as shell material showed improved oxidative stability. These findings suggests that the Maillard reaction induced conjugate of SPC and its complex coacervates can be promising encapsulating shell materials for oxidation sensitive oils.