Evaluation of Thermal Effects on the Bioactivity of Curcumin Microencapsulated with Porous Starch-Based Wall Material Using Spray Drying

Curcumin was microencapsulated with porous starch using a spray dryer with a particle size between 1.5 and 2.0 µm and subjected to water bath (40–100 °C) and oven heating (150–200 °C) in comparison to non-encapsulated samples. The minimum possible encapsulation rate ranged from 26.75 to 52.23%. A reasonable thermal stability was observed after water bath heating with regard to 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) scavenging activity. On the other hand, the increase in oven heating temperature caused significant alterations compared with the control samples (p < 0.05). The encapsulated particles subjected to oven heating at 170 °C demonstrated serious collapse. The DPPH scavenging activity of non-encapsulated curcumin was significantly reduced (p < 0.05) from 48.94% ± 3.72% (control, 0 °C) to 40.42% ± 2.23% (oven heating, 160 °C); however, remaining instead stable (p < 0.05) for the encapsulated samples (51.18% ± 4.86%–50.02% ± 1.79%) without significant difference (p < 0.05). The ABTS scavenging activity was promoted as a function of the oven heating temperature. Both DPPH and ABTS free radical scavenging activities remained stable after water bath. Nevertheless, the color of microencapsulated curcumin was better preserved on applying in comparison to the controls.