Selection criteria of lactic acid bacteria to be used as starter for sweet and salty leavened baked products

One hundred lactic acid bacteria from Italian sourdoughs were characterized for technological features and selected for their tolerance to stress conditions commonly encountered within the production of leavened fermented bakery products. Specifically, lactic acid bacteria belonging to the family Lactobacillaceae were evaluated for the capability to withstand acidic conditions (pH 3.5, 4.0, 4.5, 5.5, 6.5) and to cope with different concentrations of NaCl (2, 3, 4, 5, 6, 8%), ethanol (2, 4, and 6%) and sucrose (20 and 30%) during 48 h fermentation. Strains were also tested for urease, amylase, proteolytic activities and for the capability to produce exopolysaccharides. The strains had a wide diversity in stress response pattern. Fructilactobacillus sanfranciscensis PE4, Furfurilactobacillus rossiae PS48, Levilactobacillus brevis PA6 and two strains of Leuconostoc pseudomesentereoides (PW2 and PD4) showed the highest survival to stress treatments and interesting technological properties (i.e. amino acid and exopolysaccharides production). Several strains exhibited high robustness also to strongest stress conditions, suggesting their potential use for applications in bakery industry. This study confirms the diversity of lactic acid bacteria to stress treatments and proposes suitable criteria for selection of competitive strains to be used in versatile way for production of different salty and sweetened leavened bakery products.