Purified exopolysaccharides from Weissella confusa 11GU-1 and Propionibacterium freudenreichii JS15 act synergistically on bread structure to prevent staling

Exopolysaccharides (EPS) can act beneficially on bread texture and prevent staling. Homopolysaccharides such as dextran have been extensively investigated in cereal products, but fewer studies have adressed heteropolysaccharides (HePS). We investigated the functional interactions of the EPS types produced by Weissella confusa 11GU-1 (dextran and ropy cell-associated polymer) and Propionibacterium freudenreichii JS15 (HePS) produced by co-fermentation process on dough and wheat bread characteristics. Purified EPS powders obtained by ultrafiltration of fermentates from Weissella single culture and co-culture with Propionibacterium supplemented at 2.5 or 5 g/kg flour increased loaf volumes by about 10% and reduced moisture loss during baking compared to control bread. Synergistic activities of Weissella and Propionibacterium EPS led to improvement with respect to crumb-firming properties. For the lower addition of co-culture EPS powder (2.5 g/kg flour, corresponding to approximately 1.5 g pure EPS/kg dough), bread crumb firmness was reduced by 30 and 36% after 72 h and 1 week storage, respectively, compare to unsupplemented control bread. Our study revealed that Weissella-Propionibacterium co-culture EPS improved bread characteristics and decreased bread staling at a low level of addition compared to Weissella single culture EPS and unsupplemented bread.