The influence of fermentation temperature on the development of exopolysaccharides in yoghurt production.

Exopolysaccharides (EPS) have potential for development and exploitation as functional ingredients with health and economic benefits in dairy industry. The information on the biosynthesis, molecular organisation and fermentation conditions of EPS is rather scarce and the kinetics of EPS formation are poorly described. This study was designed to evaluate the effect of fermentation temperature on the development of lactic acid bacteria (LAB) starters EPS production potential. The commercial starters (Harmony 1.0, TWIST 1.0 and YF-L902, Chr.Hansen, Denmark) are used for yoghurt production. Milk samples were incubated at 38° C, 40° C and 43° C for 7, 6 and 5 hours, respectively, reaching pH 4.5. EPS and lactic acid concentration, LAB colony forming units (CFU) were measured in yoghurt samples using an appropriate analytical technique or standard procedures. The production of intracellularly synthesized EPS varies roughly from 25.28 to 440.81 mg L -1 during fermentation. The fermentation temperature significantly contributes to EPS concentration because the increased rate of fermentation temperature is attributed to increased metabolic activity of LAB. Thermophilic strains produce maximal amounts of EPS under conditions optimal for growth. There isn’t established the correlation between the amount of EPS and CFU of LAB in samples fermented at different temperatur es, but there is found stable CFU concentration in samples with higher initial EPS concentration during the shelf-life of yoghurt. EPS in their natural environment are thought to play a role in the protection of the microbial cell against desiccation to phagocytosis and phage’s attack, osmotic stress, adhesion to solid surfaces and biofilm forma tion. The fermentation temperature has a crucial role for the development of yoghurt quality and functional properties.