Exopolysaccharides from co-cultures of Weissella confusa 11GU-1 and Propionibacterium freudenreichii JS15 act synergistically on wheat dough and bread texture

• We compared dextran, dextran/levan and dextran/capsular polysaccharides from Weissella as baking ingredient.
• Weissella EPS and heteropolysaccharides and β-glucan from Propionibacterium showed synergistic effects in bread.
• A cofermentation process is presented for simultaneous production of EPS, propionate and acetate.
• Natural bioingredient with organic acids and EPS for bread preservation

The storage of bread is limited by both physical (staling) and microbial (mainly fungal) spoilage. Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) and organic acids from propionibacteria (PAB) have been used to enhance texture and extend shelf-life of bakery products. In this study the functionality of EPS of Weissella confusa A3/2-1 (dextran), W. confusa F3/2-2 (dextran and levan), W. confusa 11GU-1 (dextran and ropy capsular polysaccharide) was evaluated in wheat bread. Two strains of Propionibacterium freudenreichii (Pf), shown to produce a heteropolysaccharide (Pf JS15) or a β-glucan (Pf DF30), were tested in single and mixed cultures with W. confusa (Wc). The EPS fermentates were prepared by batch fermentation of cereal- or malt-based medium using sucrose (Wc) or lactic acid (Pf) as carbon source. Incorporation of EPS from single culture fermentates and 1:1 Weissella–Propionibacterium fermentate mixtures revealed strong positive effects of dextran and ropy capsular polysaccharide produced by Wc 11GU-1 on bread staling retardation, with synergistic effects of EPS mixture from Wc 11GU-1 and Pf JS15. A co-fermentation of Wc 11GU-1 and Pf JS15 was developed to produce EPS together with antifungal organic acid mixture (acetate and propionate) in a single step process. The addition of 15% (w/w flour base) co-culture, yielding EPS, acetate and propionate concentrations of 1.5, 0.5 and 1 g/kg dough, respectively, resulted in improved bread texture, increased loaf volume and decreased crumb firming during storage for 3 days compared with control breads and breads supplemented with equivalent levels of chemical organic acids. Our data showed that EPS could compensate for the negative effects of chemical acetate and propionate in a concentration range exerting antifungal effects. The natural bioingredient produced by Wc 11GU-1 and Pf JS15 has potential for applications as antifungal, texture-building and anti-staling agent in breads, consistent with consumer demands for clean label products.