Galactose plays an important nutritional role as a source of energy and a structural component in the body. It has also been shown to have antibacterial activity limiting the invasion of some pathogens. However some people have  galactose metabolism disorders called galactosemia. It is caused by a deficiency of galactose metabolism  enzymes. In this case, it is necessary to eliminate lactose and galactose from the diet. Lactic acid bacteria differ in  their ability to metabolize galactose. The metabolism of lactose/galactose may follow the Leloir pathway (S. thermophilus, L. delbrueckii subsp. bulgaricus, L. helveticus) or the tagatose-6-P metabolic pathway (L. casei, L.  rhamnosus, L. lactis ssp. cremoris). The metabolism of lactose/galactose, which follows the tagatose-6-P pathway,  results in the accumulation of small amounts of galactose in the medium, while galactose metabolism via the  Leloir pathway is usually associated with the extracellular secretion of significant amounts of galactose. Therefore,  dairy products are characterized by different galactose content and this triggers different quality consequences.  The presence of galactose in cheese (Cheddar, Mozzarella) can cause undesirable slits and cracks to occur and also adverse changes in colour during storage and as a result of heat treatment. Consequently, the elimination of  galactose from those products would improve their quality. The elimination can take place when in the cheese  production microorganisms are applied that are genetically predisposed to the intensive use of galactose, such as  L. casei, L. rhamnosus, L. helveticus. In addition milk products that do not contain lactose and galactose can be  used in the diet of people affected by galactosemia.