Production of protein-loaded starch microspheres using water-in-water emulsion method

•Protein-loaded starch microspheres were prepared by using w/w emulsion method.•It is more effective when protein and starch with high molecular weight are used.•Increasing solute concentration in both phases increased the yield of microspheres.•Encapsulation efficiency was improved when starch to protein mass ratio increased.•This method is environment-friendly and the parameters can be readily optimized. Protein-loaded starch microspheres were prepared by water-in-water (w/w) emulsion method. The effects of the molecular weight of starch and protein used, concentration of solutes in both dispersed and continuous phases and starch to protein mass ratio on the yield, loading capacity and encapsulation efficiency were measured. These parameters were significantly higher in Bovine serum albumin (BSA)-loaded microspheres than in lysozyme-loaded microspheres. An increase in the molecular weight of starch, solute concentration in dispersed and continuous phases increased the yield. The encapsulation efficiency was significantly improved when the starch to BSA mass ratio was increased. When the starch to BSA mass ratio was 15:1, the encapsulation efficiency reached about 100 % with a loading capacity of 7.3 g/100 g. This method is more effective when both core (protein) and shell (starch) materials with high molecular weight are used. This approach is environmentally friendly and the processing parameters can be easily optimized.