ABSTRACT

Sourdoughs can be classified into three types according to the technology applied for the production. Type I sourdoughs are produced with traditional techniques; the microorganisms are kept in an active state with continuous, daily refreshments. Type II sourdoughs are semi-fluid preparations that have been created in order to assist the industrialised bread making process and serve mainly as dough acidifiers. Type III sourdoughs are dried doughs in powder form. The micro-ecosystem of spontaneously fermented sourdoughs has been extensively studied. However, in the majority of the cases, sourdough micro-ecosystems are much more complex as is the metabolic interactions between the members. Glucose, fructose, sucrose and maltose are the main flour carbohydrates. The lactic acid bacteria (LAB) may catabolize them homo-fermentatively or hetero-fermentatively. Biosynthesis of exopolysaccharides (EPS) is common among bacteria in general and LAB in particular. EPS produced by sourdough LAB exhibit similar positive effects and furthermore, for some of them, prebiotic properties have been claimed.