From gene to function: metabolic traits of starter cultures for improved quality of cereal foods.

Food fermentations with lactic acid bacteria (LAB) are employed to produce safe and shelf stable food products with characteristic flavour and texture. Advances in genomics and physiology of lactic acid bacteria enabled to link individual genetic and metabolic traits of starter cultures to specific food quality attributes. The empirical selection of starter cultures is increasingly supported by the targeted selection of functional starter cultures to achieve an improved quality of fermented foods. This review highlights recent developments related to metabolic traits of LAB that are relevant for the quality of foods; emphasis is placed on starter cultures for use in bread production. Although the food use of antibacterial metabolites of LAB is well established, antifungal compounds were only recently shown to extend the shelf life of foods. Redox reactions catalysed by LAB alter the technological functionality of proteins and influence the (off)-flavour development through lipid oxidation pathways. LAB produce polysaccharides and oligosaccharides from sucrose through the glycansucrase activities. The exploitation of glycansucrase biodiversity enables the generation of a large variety of glucans or fructans in food fermentation. Poly- and oligosaccharides influence food texture, increase the dietary fibre content of foods and can be applied to protect bacterial during culture preparation and storage. The transformation of amino acids or peptides to aroma compounds contributes substantially to food flavour of food and particularly the conversion of glutamate by LAB enables the targeted optimisation of food flavour.