Mushrooms are cultivated in compost soil infused with spores. Specialists speak of culture substrates. During the transport of the substrate to mushroom farming operations, the mushroom spores in the compost must not exceed a maximum permissible temperature – otherwise, they will die off. The cold from carbon dioxide, i.e. carbon dioxide snow, stops the natural fermentation process in the compost and maintains the compost soil at a constant temperature during transport. This reliably conserves the mushroom spores.