Masterbatch comprising one or more organic peroxides in liquid form, dispersed in a polymeric matrix comprising at least 50 wt % of a bioresin, wherein the polymeric matrix has a porosity, expressed as percentage of voids on the volume of the matrix, of 2.5-70 vol % and the concentration of water in the masterbatch is kept to 2000 ppm or less, based on the total weight of the masterbatch.