Impact of Long-Fermented Sourdough on the Technological and Prebiotical Properties of Rye Bread

The technology of fermented rye bread in Latvia has a strong traditional value. Microorganisms play an important role in the fermentation process of sourdough bread, mainly due to lactic acid bacteria (LAB). Traditional rye bread in Latvia is prepared using scalded flour and sourdough. Total fermentation time can be from 6 till 48 hours, depending on the bakery. Usually sourdough contains two to five LAB species. One of the metabolites in sourdough produced by LAB is exopolysaccharide (EPS). It has been found that 20% of the analysed strains in sourdough are able to produce EPSs from sucrose — mainly fructans and glucans are produced. The exopolysaccha-rides produced by LAB are able to bind water, improving the quality of bread, increasing the volume, delaying staling of the bread, and thus extending the shelf life. Many studies have shown that EPSs produced by LAB can improve the growth of probiotics in the human body, thus improving the immune function. Of particular interest about possible prebiotic functions are EPSs produced by LAB. Long rye bread scalding fermentation technology can improve the texture, quality, and shelf life of bread, as well as functionally affect the human immune system.