Species identification is the first step in the examination of newly isolated microorganism strains, including the cases when they are intended for application in the development of probiotic preparations or starters for different food products. The thorough identification process of newly isolated strains combines the application of different physiological, biochemical, and molecular genetic methods. The aim of the present study was to identify the species-level lactic acid bacteria (LAB) strains isolated from spontaneously fermented sourdoughs prepared from different flour types: Khorosan wheat, wheat, barley, buckwheat, spelled, spelt, and corn. Both classical phenotypic (cellular morphology characterization, and API 50 CHL) and molecular genetic methods (RAPD, ARDRA-analysis, 16S rDNA sequencing, and species-specific PCR) were applied. It was found that cultures with a short-rod morphology predominated among the 30 sourdough isolates. According to the RAPD profiles obtained, the isolates were divided into nine genotypes corresponding to nine genetically distinct strains. It was determined that individual sourdoughs made with different flour types shared cultures with a common genotype. The analysis of the physiological and biochemical profiles of the LAB isolates performed with the API 50 CHL system divided them into two groups according to their identification: Lactiplantibacillus plantarum (Lp. plantarum) 1 and Levilactobacillus brevis (Lv. brevis) 3. According to the 16S rDNA restriction profile, the LAB isolates showed two profiles corresponding to the Lp. plantarum and Lv. brevis groups. 16S rDNA sequencing and a comparison of the partially read 16S rDNA sequences of the studied isolates confirmed that some of them belonged to the Lv. Brevis species, but did not provide sufficient evidence that the rest of the cultures belonged to the Lp. Plantarum species. The species-specific PCR clearly separated the isolates from the Lp. plantarum group into two groups: isolates of the Lp. plantarum species and isolates of the Lp. paraplantarum species. The summary of the results of the conducted polyphasic taxonomic study determined the investigated LAB strains isolated from spontaneously fermented sourdoughs as representatives of the Lv. brevis, Lp. plantarum ssp. paraplantarum, and Lp. paraplantarum species.

In this study, black chokeberry (Aronia melanocarpa) juice pomace was used to enrich the extrudates from rice in order to create a functional food. A response surface methodology was applied to optimize the physical (expansion ratio, bulk density, moisture content, hardness, pellet durability index, and color) and functional (water solubility index, water absorption index) characteristics of the extrudates. A laboratory single-screw extruder was used to produce the extrudates and a full factorial experimental design was applied (N = 3²) to present the effect of the amount of chokeberry pomace (10 and 20%), the feed moisture content (14 and 20%) and the working screw speed (180 min⁻¹ and 220 min⁻¹) of the extruder on the physical and functional characteristics. The results showed that the three factors influenced all studied characteristics. An exception with statistically insignificant effect was the amount of chokeberry pomace on the expansion ratio, pellet durability index, water adsorption index, lightness, redness, and yellowness, the feed moisture content on the water solubility, water adsorption index, redness and yellowness, and the working screw speed on the bulk density and hardness.

Sourdough fermentation is an important technological process in bread production, influencing acidification, product quality, and storage stability. The present study developed and comparatively evaluated two-strain and multi-strain bacterial starter cultures for application in different flour matrices and under semi-industrial bread-making conditions. The starter cultures comprised selected strains of Lactiplantibacillus plantarum, Lacticaseibacillus rhamnosus, Levilactobacillus brevis, Limosilactobacillus fermentum, Fructilactobacillus sanfranciscensis, and Propionibacterium freudenreichii subsp. shermanii. Baker’s yeast was added separately during final dough preparation and was not part of the bacterial starter combinations. Starter performance was assessed through viable cell counts, titratable acidity, in vitro antimicrobial activity, dough fermentation time, bread volume, descriptive sensory evaluation, and the onset of visually detectable microbial spoilage under the tested storage conditions. The selected combinations adapted to the investigated flour matrices, maintained high viable cell concentrations, supported acidification, and were successfully applied in semi-industrial bread production. Several formulations showed favorable technological and descriptive sensory characteristics and delayed the appearance of visible bacterial and fungal spoilage compared with the corresponding controls. Overall, the findings demonstrate the practical potential of the developed multi-strain starter cultures for application across different flour matrices and provide a strong basis for further technological refinement and mechanistic characterization of these sourdough systems.

Sourdough fermentation is a critical technological process in bread production, directly influencing process stability, product quality, and shelf life. However, spontaneous fermentation often results in variability, limiting reproducibility and industrial applicability. This study proposes a process-oriented approach to the design of symbiotic starter cultures aimed at achieving controlled and predictable sourdough fermentation. Selected lactic acid bacteria of the species Lactiplantibacillus plantarum, Lacticaseibacillus rhamnosus, Levilactobacillus brevis, Limosilactobacillus fermentum, Fructilactobacillus sanfranciscensis and Propionibacterium freudenreichii ssp. shermanii and yeasts were combined in order to develop and select symbiotic starter cultures based on defined technological and metabolic criteria, including fermentation activity, adaptability to different flour matrices, microbial compatibility, and stability under controlled process conditions. The fermentation process was evaluated through key process indicators such as acidification dynamics and microbial behavior during sourdough fermentation. The proposed approach highlights the role of starter culture composition as a tool for process control, enabling reproducible fermentation performance and consistent product characteristics. This study provides a conceptual and technological framework for the development of controlled sourdough fermentation processes applicable to functional bread production without the use of chemical preservatives.