Abstract: A mixture of hydrogen peroxide and glycerol has been found to be a particularly effective composition as a preserving additive for raw materials, in particular foodstuffs. An organic acid, such as valeric acid, can be added to the mixture as stabiliser. By atomising the mixture, in combination with gentle shaking of the product to be treated in a device provided with means suitable for this purpose, an efficient treatment is effected with relatively low consumption of the preserving mixture. The shelf life of the products treated can be further increased by drying the surface thereof using sterile air.