Preservation of foods by fermentation depends on the principle of oxidation of carbohydrates and related derivatives to generate end-products which are generally acids, alcohol and carbon dioxide.These end-products control the growth of food spoilage microorganisms and because the oxidation is only partial, the food retains sufficient energy potential to be of nutritional benefit to the consumer Using its most rigorous, chemical definition the term ‘fermentation’ is applied to describe a strictly anaerobic process; however, the general understand-ing of the term now encompasses both aerobic and anaerobic carbohydrate breakdown processes. Most fermented foods, including the major prod-ucts that are common in the western world, as wellas many of those from other sources that are less well characterised, are dependent on lactic acid bacteria to mediate the fermentation process. The end-products of carbohydrate catabolism by these bacteria contribute not only to preservation but also to the flavour, aroma and texture, thereby helping to determine unique product characteristics. Being able to control the specific microorganisms or the succes-sion of microorganisms that dominate the microflora of foods (which is the basis of development of starter cultures) is therefore very desirable. Fermentation may also increase the nutritional quality of food by