The original and primary purpose of fermenting food substrates was to achieve a preservation effect. However, with the development of the many effective alternative preservation technologies which are now commonly available, particularly in the Western World, this is no longer the most pressing requirement and many of these foods are manufactured because their unique flavour, aroma and texture attributes are much appreciated by the consumer. However, even in these situations, the conditions generated by the fermentation are essential in ensuring the shelf-life and microbiological safety of the products. Nevertheless, there are many parts of the world where the preservation role is still the essential one and where the fermentation process is still performed on an artisinal rather than industrial basis. In many cases these fermentations have only come under scientific scrutiny in the relatively recent past and thus are still only moderately or poorly under stood.