The present invention is directed to a polymer composition (C) comprising a first propylene homopolymer (H-PP), at least one hydrocarbon oil, at least one nucleating agent and at least one antioxidant, a moulded article formed from said polymer composition, a process for gamma-ray sterilization of said moulded article and uses of hydrocarbon oil in said polymer composition for improving resistance to gamma-ray radiation and reducing discoloration after gamma-ray sterilization in said polymer composition.