Major aspects of food processing by the usage of cultures are acidification, flavor/aroma generation. However, these processes cannot be fully separated. Other attributes of cultures and their contribution to the finished products are health properties using specially selected probiotic cultures.

Acidification

Lactic fermentations are mainly characterized by the growth and metabolism of lactic acid bacteria. The most prominent food-relevant genera are Lactobacillus, Streptococcus, Leuconostoc, Lactococcus, Pediococcus and Bifidobacterium (not a lactic acid bacterium from a scientific point of view, but regarded as such in this context). Breaking down carbohydrates and other metabolic activities leads to an acidification of the food substrate, such as milk and meat. The major end-product in these processes is lactic acid, other organic acids and of course many secondary compounds, that are flavor active.

Flavor/aroma generation

The biochemistry behind generation of flavor/aroma compounds typical for dairy and meat products is complex and often not understood in detail. Basic metabolic activities are lipolysis and proteolysis of fat and proteins in the food. Typically starter microorganisms involved in this are bacteria like Staphylococcus (also involved in color formation), Brevibacterium and yeast and molds like Debaromyces, Klyveromyces, Geotrichium and Penicillium.  Especially moulds are known to cover the surface of cheese and meat products, protecting the surface and contributing to the characteristic appearance.