Stability of Anthocyanin from Mulberry Extracts in Alginate Microspheres at High Temperature

The aim of this study was to investigate stabilities of anthocyanins from mulberry fruits extracts in alginate microspheres. The total anthocyanins contents measured from water extracts of mulberry fruits (Chiangmai/Jul cultivars) were at 10.46+/-0.51 mg/g DW and 15.31+/-0.86 mg/g DW (Chiangmai/Korat cultivars). At high temperature the extracts lost their anthocyanin contents to 52%wt (at 100 degrees C for 5 hour) and 73%wt (at 121 degrees C for 20 min). Alginate microspheres were prepared using external gelation methods. Sodium alginate solution (2.5%w/v) was sprayed into CaCl2 solution (0.1 M) through a nozzle at N-2 flow rates of 20 L/min. The average bead sizes were at 342.03+/-3.21 mu m. Anthocyanins loading on alginate microspheres were at 2.283+/-0.15 mg/g dry weight. At 80(10h), 100(5h) and 121 degrees C(20min), Anthocyanins retention were at 91%wt, 82%wt and 89%wt, respectively. Adsorption of anthocyanins from mulberry fruit extracts on alginate microspheres resulted in a greater stability at high temperature than that of the free anthocyanins.