Interaction between lactic acid bacteria and yeasts in sour-dough using a rheofermentometer

Area of Science:

• Food Science
• Microbiology
• Fermentation Technology

Background:

• Sourdough fermentation relies on a complex interplay between yeasts and lactic acid bacteria (LAB).
• Understanding microbial contributions is key to optimizing sourdough leavening and texture.
• Previous research indicates varied impacts of different microbial species on fermentation.

Purpose of the Study:

• To characterize the leavening properties of sourdoughs produced with specific LAB and yeast strains.
• To investigate the combined effects of yeast and LAB on carbon dioxide (CO2) and ethanol production.
• To evaluate the influence of fructose on sourdough fermentation dynamics.

Main Methods:

• Rheofermentometer assays were employed to measure gas production during sourdough fermentation.
• Selected strains of Saccharomyces cerevisiae and various lactic acid bacteria (LAB) were used, individually and in combination.
• The impact of fructose addition on fermentation was assessed.

Main Results:

• Saccharomyces cerevisiae 141 demonstrated the highest CO2 and ethanol production.
• S. exiguus M14 and Lactobacillus brevis subsp. lindneri CB1 showed poor leavening, resulting in non-porous sourdough.
• Heterofermentative LAB accelerated yeast fermentation, while homofermentative LAB slowed it but increased CO2 output.
• Combining L. brevis subsp. lindneri CB1 with S. cerevisiae 141 reduced bacterial activity, an effect mitigated by fructose addition.

Conclusions:

• Microbial selection is critical for achieving desired sourdough leavening and texture.
• S. cerevisiae is a potent leavening agent, and its activity can be modulated by co-fermenting LAB.
• Fructose can enhance fermentation by specific LAB and yeast strains, overcoming limitations in mixed cultures.