In a process to reduce the germ count in a charge of particulate herbs or spices (50), the container (2) is almost entirely filled and subjected to horizontal shaking, followed by the release of hot steam into the container. Also claimed is a suitable assembly in which a container is supported by a frame (6) with a vibrator mechanism (24) moving through a range of pref. more than 20 mm. After filling the container and introduction of hot steam, the supply of steam is cut off and the container sealed and evacuated while the shaking continues for a period which is determined by the temperature within the container or the temperature of the charge.