Maltodextrin: A consummate carrier for spray-drying of xylooligosaccharides

The aim of this study was to evaluate the influence of spray-drying on the powder qualities and microstructures of prebiotic xylooligosaccharides (XOS). The relationships between glass transition temperature (T_g) and XOS retention, moisture content, drying yield as well as specific surface area under different inlet air temperatures and maltodextrin concentrations were investigated. Antioxidant activity retention, hygroscopicity, color attributes, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) of the spray-dried XOS product were also assessed. The results indicated that an increase in inlet air temperature decreased the moisture content, hence the T_g value was increased. Higher maltodextrin concentration increased the T_g value, and was attributed to the molecular weight increase. The wall deposition was a tendency to occur when the temperature beyond the T_g, reduced the drying yield. Higher temperature and wall deposition promoted the decomposition of XOS into monosaccharide. The crust formation rate of droplets and stickiness of microparticles were affected by T_g, and hence, influenced the specific surface area. The antioxidant activity retention of XOS exhibited a concentration-dependent behavior. The hygroscopicity of the microparticles could be reduced by both of the low inlet air temperature and high maltodextrin concentration. According to the results of color attributes, XRD and SEM, the particles were colorless and amorphous, and tended to become more spherical and scattered with the addition of maltodextrin. The FT-IR analysis confirmed that no chemical reaction occurred between XOS and agent, which indicated that maltodextrin is a promising carrier for producing bioactive XOS powder.