Flavour development in dairy fermentations is the result of a series of chemical and biochemical processes during ripening. Starter lactic acid bacteria provide the enzymes involved in the formation of specific flavours. Amino acids, and in particular methionine, the aromatic and the branched-chain amino acids, are major precursors for volatile aroma compounds. The recent sequencing of complete genomes of several lactic acid bacteria (i.e. Lactococcus lactis, Lactobacillus plantarum, Streptococcus thermophilus) is beginning to provide insight into the full complement of proteins that may be involved in flavour-forming reactions, and hence the potential for formation of specific flavour compounds. Examples are given how bioinformatics tools can be used to search in genomes for essential components, such as proteinases, peptidases, aminotransferases, enzymes for biosynthesis of amino acids, and transport systems for peptides and amino acids.