Biotechnological characterization of lactic acid bacteria and yeast isolates from spontaneous sourdough for the development of bread with postbioticlike potential

Abstract

Sourdough (SD) is defined as the fermentation of flour, water, and otheringredients by lactic acid bacteria (LAB) and yeasts, which can be grownspontaneously from the flour and the environment or be inoculated as starter microorganisms. This a well-known biotechnological process that has shown the capability to improve the sensory, rheological, and shelf-life properties of baked goods. SD is an ecosystem characterized by a higher cell count of LAB over yeasts in terms of microbiological composition. In the last years, the presence of postbioticlike components has been associated with SD fermentation and SD bread. Postbiotics refer to a group of inanimate microorganisms and/or their components that confer health benefits to the host. Examples of postbiotic-like components are exopolysaccharides, short-chain fatty acids (SCFAs), bacteriocins, biosurfactants, amino acids, and cell surface biotechnological properties of LAB and yeasts isolated from spontaneous wholewheat SD and raspberry to generate defined microbial starter cultures useful for the development of novel functional breads with enhanced technological, and postbiotic properties. in identified species were Candida glabrata, Saccharomyces cerevisiae, Pediococcus pentosaceus, ompanilactobacillus paralimentarius and Latilactobacillus curvatus. Biotechnological and functional properties were assayed for the 25 isolated microorganisms and three commercial probiotic strains for 7 comparative purposes. LAB and yeast isolates showed the ability to release free amino acids by the action of proteolytic enzymes, and the ability to release phenolic compounds. Yeast isolates denoted a higher leavening capacity than LAB isolates, whereas LAB isolates presented a high phytase activity compared to yeast isolates. The results from a statistical analysis using Principal Component Analysis and Cluster Analysis and the microbiological performance allowed the selection of P. pentosaceus BIOTEC032, C. glabrata BIOTEC021, S. cerevisiae BIOTEC026 and Hanseniaspora. opuntiae BIOTEC045 to be used as starter cultures in the formulation of wheat breads. Eight types of wheat bread were elaborated using selected starter cultures (in combination or not with SD fermentation). Cell counts of LAB and yeasts, pH, TTA, biotechnological and postbiotics properties, physical characteristics and sensory evaluation were performed for the 8 bread treatments. The loaves of bread containing LAB in combination with SD, particularly Bac+Yeast SD and Bacteria SD, exhibited the best results for the postbiotic-like properties (total phenol content, phytase activity, antioxidant activity and presence of exopolysaccharides), and microbiological and acidification features. For the physical characteristics, the bread with a yeast combination (Yeast bread) had the softness property, whereas Bac+Yeast SD and Bacteria SD treatments were the hardest loaves. Finally, differences in color and sensory acceptance between the eighth treatments were not detected (P < 0.05). These results confirm that the use of defined consortiums of LAB and yeast as starter cultures for SD bread production enhances the nutritional, biotechnological and potential postbiotic properties of the baking breads.