Abstract
In this study, the potential of Leuconostoc as non-conventional sourdough starter cultures was investigated. A screening for antifungal activities of 99 lactic acid bacteria (LAB) strains revealed high suppression of bakery-relevant moulds in nine strains of Leuconostoc with activities against Penicillium sp., Aspergillus sp., and Cladosporium sp. Mannitol production was determined in 49 Leuconostoc strains with >30 g/L mannitol in fructose (50 g/L)-enriched MRS. Further, exopolysaccharides (EPS) production was qualitatively determined on sucrose (40 g/L)-enriched MRS agar and revealed 59 EPS positive Leuconostoc strains that harboured dextransucrase genes, as confirmed by PCR. Four multifunctional Lc. citreum strains (DCM49, DCM65, MA079, and MA113) were finally applied in lab-scale sourdough fermentations (30 °C, 24 h). Lc. citreum was confirmed by MALDI-TOF MS up to 9 log CFU/g and pH dropped to 4.0 and TTA increased to 12.4. Antifungal compounds such as acetic acid, phenyllactic and hydroxyphenyllactic acids were determined up to 1.7 mg/g, 2.1 µg/g, and 1.3 µg/g, respectively, mannitol up to 8.6 mg/g, and EPS up to 0.62 g/100 g. Due to the observed multifunctionalities and the competitiveness in the natural flour microbiota present in sourdoughs, non-conventional LAB genera such as Leuconostoc seem promising for application in sourdough-based bakery products.
Highlights
Based on metabolic activities, the application of a lactic acid bacteria (LAB) fermentation is used broadly in the food industry, e.g., for traditional sourdough fermentation [1].LAB mainly belonging to species of the former genus of Lactobacillus that were recently classified by Zheng et al [2] into the novel genera Lactiplantibacillus (Lpb.) plantarum subsp.plantarum (former: Lactobacillus (Lb.) plantarum), Levilactobacillus (Lev.) brevis, and Fructilactobacillus (F.) sanfranciscensis dominate the sourdough microbiota [3]
Derived mannitol mainly produced by heterofermentative LAB [6] such as Lc. citreum can be used as sugar substitute that is relevant for the baking industries in the production of sugarreduced baked goods [7]
This study assessed the use of Lc. citreum as non-conventional LAB starter cultures with techno-functional characteristics and their suitability in sourdough fermentations
Summary
The application of a lactic acid bacteria (LAB) fermentation is used broadly in the food industry, e.g., for traditional sourdough fermentation [1].LAB mainly belonging to species of the former genus of Lactobacillus that were recently classified by Zheng et al [2] into the novel genera Lactiplantibacillus (Lpb.) plantarum subsp.plantarum (former: Lactobacillus (Lb.) plantarum), Levilactobacillus (Lev.) brevis (former: Lb.brevis), and Fructilactobacillus (F.) sanfranciscensis (former: Lb. sanfranciscensis) dominate the sourdough microbiota [3]. The application of a lactic acid bacteria (LAB) fermentation is used broadly in the food industry, e.g., for traditional sourdough fermentation [1]. LAB mainly belonging to species of the former genus of Lactobacillus that were recently classified by Zheng et al [2] into the novel genera Lactiplantibacillus (Lpb.) plantarum subsp. The application and suitability of these LAB genera as starter cultures in sourdough fermentations has been researched for years [3,4]. Non-conventional LAB genera such as Leuconostoc (Lc.) and Weissella (W.) are still less studied but bear high potential as starter cultures in sourdough fermentations due to their adaptation and performance in sourdough fermentations [5]. The formation of microbial exopolysaccharides (EPS) as a natural texture enhancing agent has been studied by Chen et al [8] and was extensively studied in, e.g., Leuconostoc, Weissella, and species of the former genus of Lactobacillus such
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