The use of sourdough improves the quality and increases the shelf life of bread. The positive effects are associated with metabolites produced by lactic acid bacteria (LAB) during sourdough fermentation, including organic acids, exopolysaccharides (EPS), and enzymes. EPS formed during sourdough fermentation by glycansucrase activity from sucrose influence the viscoelastic properties of the dough and beneficially affect the texture and shelf life (in particular, starch retrogradation) of bread. Accordingly, EPS have the potential to replace hydrocolloids currently used as bread improvers and meet so the consumer demands for a reduced use of food additives. In this review, the current knowledge about the functional aspects of EPS formation by sourdough LAB especially in baking applications is summarized.
The addition of sourdough fermented with lactic acid bacteria synthesizing organic acids and oligo- and exopolysaccharides (EPS) from sucrose enhances texture, nutritional value, shelf life, and machinability of wheat, rye, and gluten-free bread. This study compared acetate, mannitol, and oligosaccharide formation of EPS-producing strains of Weissella and Leuconostoc spp. to the traditional sourdough starter Lactobacillus sanfranciscensis. In broth, Leuconostoc strains generally formed acetate and mannitol, whereas Weissella produced only small amounts of acetate and no mannitol in the presence of sucrose. In the presence of sucrose and maltose, Weissella and Leuconostoc strains synthesized glucooligosaccharides and EPS. Strains of Weissella were employed as starter cultures for wheat and sorghum sourdough and formed 0.8−8 g kg−1 EPS and gluco-oligosaccharides but only low amounts of acetate and mannitol. In contrast, the formation of EPS from sucrose led to the production of high amounts of acetate and mannitol by L. sanfranciscensis LTH 2950 in wheat sourdough. This study indicates that Weissella strains are suitable starter cultures for wheat and sorghum sourdoughs and efficiently produce gluco-oligosaccharides and EPS.
The aims of this study were to identify antifungal lactic acid bacteria (LAB) and characterize their activity against the dermatophyte Trichophyton tonsurans.A total of 165 different LAB were isolated and initially screened for anti-Penicillium expansum activity. Five strains, which exhibited strong inhibitory activity, were then tested against the dermatophyte T. tonsurans DSM12285, where they also caused inhibition as observed by large fungal clearing on agar surface. The strongest inhibition was seen with Lactobacillus reuteri R2. When freeze-dried cell-free supernatant powder from this strain was incorporated in culture medium at concentrations >1%, growth of fungal colony was inhibited. Conidia germination was also inhibited under these conditions as determined by microscopy. The anti-T. tonsurans activity of Lact. reuteri R2 was not affected neither by heat treatment nor by proteolytic treatment using pronase E and proteinase K, indicating that the responsible agent(s) were nonproteinaceous in nature.Lactobacillus reuteri R2 was identified as having strong inhibitory activity against the dermatophyte T. tonsurans DSMZ12285.LAB are naturally associated with many foods and are well recognized for their biopreservative properties. The use of these and/or their products may well provide alternative safe approaches for the inhibition of dermatophytic fungi.
Feeding fermented feed to weaned pigs may improve nutrient digestibility and gut health and thereby reduce diarrhea incidence. Effects of feeding wheat grain fermented for 24 h with were evaluated with 36 weaned pigs (7.3 kg BW). Fermented wheat grain contained (DM basis) 14.2% CP, 0.45% chemically available Lys, and 7.8% NDF, whereas unfermented wheat grain contained 16.4% CP, 0.45% chemically available Lys, and 9.9% NDF. Pigs were fed 6 mash wheat-based diets balanced for water content during 2 phases: Phase 1 diets for 1 wk (d 0-7) with 20% unfermented or fermented wheat and, subsequently, Phase 2 diets for 2 wk (d 8-21) with 50% unfermented or fermented wheat. The 6 diets were unfermented wheat (CTRL), unfermented and chemically acidified wheat (ACD), fermented wheat with TMW1.656 and 10% sucrose, fermented wheat with TMW1.656 and 5% glucose + 5% fructose, fermented wheat with LTH5794 and 10% sucrose, and fermented wheat with LTH5794 and 5% glucose + 5% fructose. Diets were formulated to provide 2.5 and 2.4 Mcal NE/kg and 5.3 and 5.0 g standardized ileal digestible Lys/Mcal NE for Phase 1 and 2 diets, respectively. Feeding fermented wheat reduced ( < 0.05) apparent total tract digestibility (ATTD) of diet DM (84.7 vs. 85.4%), GE (84.4 vs. 85.3%), and CP (81.8 vs. 83.6%) for d 15 through 21 compared with the CTRL and ACD diets. Weaned pigs fed fermented wheat diets had lower ( < 0.05) ADFI than pigs fed the CTRL and ACD diets for d 0 through 7. The ADFI, ADG, and G:F did not differ between pigs fed fermented and unfermented diets. Concentrations of acetic, propionic, and branched-chain fatty acids and total VFA in feces increased ( < 0.05) for pigs fed fermented wheat diets containing exopolysaccharides (EPS). However, VFA did not differ in ileal digesta. Villus height in the duodenum and jejunum increased in pigs fed fermented wheat without EPS ( < 0.05) compared with pigs fed fermented wheat with EPS. However, pigs fed the CTRL and ACD diets had longer ( < 0.05) villi and deeper crypts in the ileum than pigs fed fermented wheat. The ratio of villus height to crypt depth did not differ in the 3 segments of small intestine of weaned pigs. In conclusion, feeding fermented wheat grain diets to weaned pigs did not affect gut morphology, intestinal fermentation, growth performance, and ATTD of nutrients; however, EPS stimulated hindgut fermentation and may promote health benefits.
The growing interest of governments and industry in developing healthy and natural alternative foods and beverages that will fulfil the consumer drive towards a healthy lifestyle and clean-label, natural diet has led to an increase in traditional lactic acid bacteria fermentation research. In particular, this research aims to address the organoleptic modulation of beverages using in situ-produced bacterial polysaccharides.Weissella cibaria MG1 is capable of producing exopolysaccharides (dextran) and oligosaccharides (glucooligosaccharides) during sucrose-supplemented barley-malt-derived wort fermentation. Up to 36·4 g l(-1) of dextran was produced in an optimized system, which improved the rheological profile of the resulting fermentate. Additionally, small amounts of organic acids were formed, and ethanol remained below 0·5% (v/v), the threshold volume for a potential health claim designation.The results suggest that the cereal fermentate produced by W. cibaria MG1 could be potentially used for the production of a range of novel, nutritious and functional beverages.Using conventional raw materials and traditional processes, novel LAB-fermented beverages can be produced representing an innovative mechanism towards fulfilling the aim to decrease government and personal costs as well as potentially ameliorating consumer lifestyle regarding dietary-related disease.
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