A READY-TO-USE LIQUID SOURDOUGH FOR THE PRODUCTION OF "YEAST-FREE" BREAD

The aim of this study was the development of a biotechnological protocol to produce "yeast-free" bread by using a ready-to-use liquid sourdough. A selection of suitable LAB strains, mainly based on the leavening ability, was carried out by the characterization of 12 strains belonging to 8 species of lactic bacteria. The results allowed selecting two very promising strains, Leuconostoc citreum C2.27 and Weissella confusa C5.7, which were used for bread-making laboratory tests. After fermentation, the liquid sourdoughs singly inoculated with the two starter strains as well as bread doughs were subjected to chemical-physical (pH, volume, TTA, concentration of lactic and acetic acids, free amino acids) and microbiological (determination of total lactic bacteria, yeasts and molds) analyses. Bacteria and yeasts were isolated from liquid sourdoughs and doughs, genetically characterized and identified. Both the selected strains were suitable for the production of bread without baker's yeast, however the L. citreum C2.27 showed the highest leavening capacity and was able to dominate the dough microbiota. In fact, it was the only bacterial strain identified in both the liquid sourdough and the bread dough, in the absence of yeasts at the same time. The applicability of the developed protocol, adapted for the production of a typical Apulian bread, and the suitability of the L. citreum C2.27 strain were confirmed at pilot scale in an industrial bakery. The "puccia" bread, made without baker's yeast, was similar in appearance to bread containing baker's yeast and its sensory characteristics were judged positively (De Bellis et al., 2019). References: De Bellis P., Rizzello C.G., Sisto A., Valerio F., Lonigro S.L., Conte A., Lorusso V., Lavermicocca P. Use of a selected Leuconostoc citreum strain as a starter for making a "yeast-free" bread. Foods, 2019, 8(2), 70; doi: 10.3390/foods8020070