**3.1 Preparation of alginate/κ-carrageenan and alginate/gelatin hydrogel beads and curcumin loading**

Alginate, κ-carrageenan and gelatin solutions were prepared separately by dissolving each of the biopolymers in distilled water and heated up at 50°C (for alginate), 60°C (for κ-carrageenan) and 40°C (for gelatin) under constant stirring from 30 min to 1 h until complete dissolution [50]. Ionotropic method was used for the preparation of hydrogel beads. Polysaccharide mixture composed of 50:50, 70:30, 80:20 (weight ratio) with concentrations varying from 1 to 2.5% (given in **Table 1**) were prepared by mixing under constant stirring at 30°C for 30 min. Briefly the hydrogel beads were prepared by dropping the mixture through a plastic syringe (5 ml) into an aqueous salt solutions stirred magnetically. For the preparation of alginate/κ-carrageenan hydrogel beads, the salt solution was composed of 100 ml of 2% (w/v) KCl and 100 ml of 2% (w/v) CaCl2 and for alginate/gelatin hydrogel beads, 200 ml of 2% CaCl2 solution. To complete gelation, beads were maintained in the solution for 30 min then filtered, followed by washing with distilled water and then allowed to dry overnight at 37°C.

For curcumin loading, 10 mg/ml curcumin prepared with ethanol was mixed with each of the alginate/κ-carrageenan and alginate/gelatin mixtures and stirred until complete evaporation of ethanol. Curcumin loaded beads were prepared by dropping the mixture through a 5 ml syringe into a stirred salt solution which was composed of 100 ml of 2% (w/v) KCl and 100 ml of 2% (w/v) CaCl2 in the case of alginate/κ-carrageenan and 200 ml of 2% (w/v) CaCl2 for alginate/gelatin and kept in the solution for 30 min, filtered, washed with distilled water and dried overnight at 37°C.
