The development of the correct flavour characteristics is a critical factor in the production of a range of fermented foods. However, the specific mechanisms by which flavour is generated is not fully understood, although the principal components contributing to flavour, such as protease, peptidase and lipase activities may be known. This is well exemplified in a product such as Cheddar cheese where the fine and subtle flavour attributes of the mature product is an essential element in determining the quality of the cheese. There now exists the ability to manipulate the proteolytic system of certain lactic acid bacteria, albeit in a crude way (McGarry et al.,1994; Mierau et al. 1996). Other recent advances related to an understanding of the pathways of amino acid metabolism and the role of cell lysis during product maturation will not only illuminate the allow this characteristic to be controlled and modified according to the needs of the market