Preparation and radical scavenging activities of polymeric procyanidins nanoparticles by a supercritical antisolvent (SAS) process

► Nanoscale polymeric procyanidins (PPC) was first made by supercritical antisolvent. ► Solubility of nanoscale PPC increased significantly without any chemical reaction. ► The DPPH radical scavenging capacity of nanoscale PPC was significantly increased. ► The result indicates that nanoscale PPC might be an excellent natural antioxidant. The aim of this study was to prepare nanoscale polymeric procyanidins (PPC) by the supercritical antisolvent precipitation process (SAS), to improve the radical scavenging activities of PPC. Nanoscale PPC was successfully achieved by SAS. The effects of process parameters like temperature, pressure, solution flow rate and solution concentration have been investigated to reveal their impact on the mean particle size of the final product. We obtained microspheres with mean diameters ranging from 100 to 200nm. The processed and unprocessed PPC was characterised by scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis, differential scanning calorimeters, fourier-transform infrared spectroscopy and specific surface area analysis. The solubility of PPC precipitated using SAS process was significantly increased in comparison with unprocessed PPC. Moreover, the nanoscale PPC demonstrated higher antioxidant activities than unprocessed PPC. These results indicate that nanoscale PPC might be of interest to be used as a natural antioxidant.