Refrigerators should not be overloaded and they need packing in a manner which allows good air circulation. A gap of at least 3cm should always be allowed between trays stored on slatted shelves. Food should not be placed directly in front of the cooling unit as this reduces efficiency. Non-perishables should not be stored in a refrigerator if this takes up valuable space. Good stock rotation is essential, and daily checks should be made for out-of-date stock. Stock rotation is important because of the slow growth of mould. Spoilage bacteria and especially the pathogen Listeria monocytogenes. Particular care is required with soft cheese and pate which have been associated with listeria outbreaks.