Yeasts have been associated with foods since earliest times, both as beneficial agents and as major causes of spoilage and economic loss. Current losses to the food industry caused by yeast spoilage are estimated at several million pounds annually in the UK alone. As new food ingredients and new food manufacturing technologies are introduced, novel food spoilage yeasts are emerging to present additional problems. Consumer demand for milder food preservation regimes and tougher regulatory constraints on hygiene in the production environment all serve to increase the economic severity of problems caused by yeasts.