Abstract: The invention relates to a method for reducing the virus and micro-organism content of biological extracts which contain solids. It is provided that the method comprises the steps (a) provision of a biological extract which contains solids in the form of a suspension, which consists of a liquid phase and solid particles dispersed therein, wherein the extract in step (a) comprises a mixture of enzymes, proteins and peptides, some of which is dissolved in the liquid phase and some of which can be bound to the solid particles or is present in pulverulent, solid form; and (b) irradiation of the biological extract provided in step (a); wherein the radiation used for the irradiation is selected from the group comprising ultra-violet radiation, x-ray radiation, ? radiation and ? radiation; and the enzymic activity of the biological extract which contains solids after irradiation is at least 50% of the enzymic activity of the biological extract which contains solids before irradiation.