Selection of cereal-sourced lactic acid bacteria as candidate starters for the baking industry

Abstract

The quality of sourdough bread mainly depends on metabolic activities of lactic acid bacteria (LAB). The exopolysaccharides (EPS) produced by LAB affect positively the technological and nutritional properties of the bread, while phytases improve the bioavailability of the minerals by reducing its phytate content. In the present study, a pool of 152 cereal-sourced LAB were screened for production of phytases and EPS for potential use as sourdough starter cultures for the baking industry. There was large heterogeneity in the phytase activity observed among the screened isolates, with 95% showing the ability to degrade sodium phytate on plates containing Sourdough Simulation Medium (SSM). The isolates Lactobacillus brevis LD65 and Lactobacillus plantarum PB241 showed the highest enzymatic activity, while the isolates ascribed to Weissella confusa were characterized by low or no phytase activity. Only 18% of the screened LAB produced EPS, which were distinguished as ropy or mucoid phenotypes on SSM supplemented with sucrose. Almost all the EPS producers carried one or more genes (epsD/E and/or epsA) involved in the production of heteropolysaccharides (HePS), whereas the isolates ascribed to Leuconostoc citreum and W. confusa carried genes involved in the production of both HePS and homopolysaccharides (HoPS). Monosaccharide composition analysis of the EPS produced by a selected subset of isolates revealed that all the HePS included glucose, mannose, and galactose, though at different ratios. Furthermore, a few isolates ascribed to L. citreum and W. confusa and carrying the gtf gene produced β-glucans after fermentation in an ad hoc formulated barley flour medium. Based on the overall results collected, a subset of candidate sourdough starter cultures for the baking industry was selected, including Lb. brevis LD66 and L. citreum PB220, which showed high phytase activity and positive EPS production.

Innovative Fermented Beverages Made with Red Rice, Barley, and Buckwheat

“…Though lactobacilli are known to potentially produce enzymes able to degrade phytates (phytases) at the low pH values reached during fermentation [ 61 ], in the present study, no effect of the multiple strain starter inoculation on the phytate content of the three beverages was seen. This latter finding might be feasibly explained by the lack of phytase activity by the strains used for the formulation of the three multiple strain starters, selected based on their performance as natural acidifiers.…”

Technological and Safety Attributes of Lactic Acid Bacteria and Yeasts Isolated from Spontaneously Fermented Greek Wheat Sourdoughs

“…Another property with technological impact, however, not detected in the present study, was EPS production by LAB strains. On the contrary, previous studies by Milanović et al [ 64 ] and Manini et al [ 49 ] reported the presence of EPS producing LAB strains, derived from cereal based substrates and wheat bran sourdoughs, respectively. A last safety attribute assessed in the present study, but what was not detected in either LAB or yeast strains tested was the ability to form BAs.…”

Functional and Healthy Features of Conventional and Non-Conventional Sourdoughs

“…A recent screening on 152 LAB, isolated from cereal-based substrates, revealed a widespread capacity of the isolates (95%) for degrading phytic acid. Among the isolates, strains L. brevis LD65 and L. plantarum PB241, showed the highest phytase activity; on the contrary, Weissella confusa strains showed low or no phytase activity [62].…”

“…A recent screening on 152 LAB, isolated from cereal-based substrates, revealed a widespread capacity of the isolates (95%) for degrading phytic acid. Among the isolates, strains L. brevis LD65 and L. plantarum PB241, showed the highest phytase activity; on the contrary, Weissella confusa strains showed low or no phytase activity [62]. In particular, the flavor profile of the product can be greatly affected by the use of sourdough, depending on type of starter cultures, fermentation conditions, baking conditions and raw material.…”