Abstract: In this study, two high-yield exopolysaccharide (EPS)-producing strains of lactic acid bacteria (LAB), Weissella cibaria T5 and Weissella confusa J28, which were respectively isolated from Chinese rice wine koji and traditional sourdough, were used to make buckwheat sourdough. The aim was to investigate the effects of the two strains on dough microstructure and bread quality. Both J28 and T5 produced high molecular weight dextran. J28 produced higher amounts (11.87 g/kg vs. 9.36 g/kg) of EPS but significantly lowers amounts of acetic acid than did T5 in buckwheat sourdough. Compared with bread with the addition of 30% EPS-negative buckwheat sourdough, EPS produced by both T5 and J28 could improve the structure of the gluten network in dough and the specific volume and softness of bread, with the former being more effective. Compared with the control bread, the bread made from 30% EPS-positive buckwheat sourdough fermented by J28 had the best quality and was more favored by consumers.

Key words: lactic acid bacteria, exopolysaccharide, buckwheat, sourdough, baking