Why do food and drink smell like earth?

Fungi have long been associated with earthy odours. One of the main contributors to this odour is geosmin, a sesquiterpenoid metabolite produced by soil living fungi. Some food commodities are liable to contamination by geosmin producing fungi. Under favourable environmental conditions the production of geosmin occurs. One of the producers of geosmin in fruits is Penicillium expansum which also produces the mycotoxin patulin. Recent reports indicate that geosmin production by P. expansum is stimulated by Botrytis cinerea. However, the effect on patulin production is not known. The above issues will be discussed in this contribution.Fundação para a Ciência e a Tecnologia (FCT