Photostability and characterization of spray-dried maltodextrin powders loaded with Sida rhombifolia extract

Sida rhombifolia extracts, obtained by pressurized liquid extraction (PLE), were microencapsulated in maltodextrin (MD) by spray drying. Different formulations were prepared with MD at 20% (w/w) and with 2.5, and 5.0% of S. rhombifolia extract, called ME2.5, and ME5.0, reaching an encapsulation efficiency of 89, and 94%, respectively. Scanning electron microscopy (SEM) and fluorescence microscopy enable the determination of the particles average size of 3.07 mu m, and confirmed the extract encapsulation in MD. Besides, the phenolics autofluorescence allowed the correlation with the extract compounds, mainly 3-O-beta-D-glycoside. The Fourier transform infrared (FTIR) results show no interaction between the coating material (MD) and the microcapsules core (extract). The produced powder was characterized by colorimetric analyzes, solubility isotherms, kinetics, and moisture adsorption, in addition to thermal analyzes. Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) indicated 64.6 and 53.4% of mass loss for ME2.5 and ME5.0, respectively. The microparticles photostability, evaluated in a self-assembled UVA/UVB emission chamber, showed 93.8 and 84.5% stabilization of total phenolic compounds (TPC) for ME2.5 and ME5.0, respectively. Given the high encapsulation efficiency and the preservation of extract quality, this study results suggest the possibility to use the loaded microcapsules in formulations for food and nutraceutical industries.