Sourdough has traditionally been used as leavening agent in artisanal baking. The production of baked and steamed cereal products increasingly employs sourdough as baking improver to achieve improved ...bread quality, or to obtain “clean label” products. Sourdoughs are maintained in bakeries by continuous propagation; composition and metabolic activity of sourdough microbiota and their impact on bread quality are therefore shaped by processing parameters and fermentation substrates. The diversity of fermentation processes leads to diverse compositions of sourdough microbiota. This communication explores whether concepts in community assembly support an improved understanding of the microbial ecology of sourdough. Community assembly is determined by diversification, drift, dispersal, and selection. Evidence for diversification in sourdoughs is inconclusive. Drift has been shown to shape sourdough microbiota only in specific cases. Increasing knowledge on the primary habitat of sourdough lactobacilli indicates that dispersal (limitation) is an important determinant in sourdoughs that are propagated only for short periods of time. In contrast, selection of adapted organisms mainly determines the microbiota of sourdoughs that are propagated for a long time. Bacterial metabolic traits that determine competitiveness in sourdough fermentation, i.e. effective use of maltose, exopolysaccharide formation from sucrose, the use of electron acceptors by heterofermentative lactic acid bacteria, and acid resistance mediated by arginine and glutamine conversion, also determine bread quality. The concepts in community assembly thus provide a valuable tool to understand the influence of the technology of sourdough fermentation on microbial ecology and on bread quality.
The novel cereal ‘Tritordeum’ was employed in sourdough fermentation for bread making using a traditional backslopping procedure over 10 days. Culture-dependent and culture-independent approaches ...were used to characterize microbial ecology during sourdough preparation and propagation. Sourdough reached the highest microbial diversity after three days of propagation. Microbial diversity decreased as sourdough reached maturity (day 5). Microbiota dominance shifted from Weissella to Lactiplantibacillus genera after 5 days of propagation. Lactic acid bacteria (LAB) showed a constant increase throughout the propagations starting from 3.9 ± 0.24 log CFU g−1 on day 0 up to 8.0 ± 0.39 log CFU g−1 on day 5. Weissella confusa/cibaria and Weissella paramesenteroides were the most prevalent LAB species until day 5 of propagation, while Lactiplantibacillus plantarum was the most prevalent thereafter. Yeasts were present in low cell density (2.0 ± 0.11 log CFU g−1) until the fourth backslopping (day 4) and then gradually increased until day 10 (5.0 ± 0.29 log CFU g−1), with Saccharomyces cerevisiae being the most prevalent and dominant species. Lactic and acetic acid concentrations increased throughout Tritordeum sourdough propagations, indicative of a proportional decrease of fermentation quotient (lactic acid/acetic acid) from 13.54 ± 1.29 to 4.08 ± 0.15. Utilization of glucose, fructose and sucrose was observed, followed a progressive increase in mannitol concentrations beginning from day 4. The nutritional potential (total phenol content, antioxidant activity, dietary fiber content and total free amino acids) remained elevated during sourdough propagations. Antinutritional factors (phytic acid and raffinose) were reduced to minimal concentrations by day 10. Finally, texture analysis of Tritordeum sourdough bread was demonstrated to have better cohesiveness, resilience and firmness compared to baker's yeast bread, confirming its potential to improve functionality and use in sourdough biotechnology.
•Tritordeum proved to be a suitable cereal for type I sourdough biotechnology.•The sourdough reached maturity after five days of propagation.•Lactiplantibacillus plantarum dominated the sourdough microbiota from day 5 onwards.•Nutritional and biochemical features were stabilized between day 5 and day 7 of propagation.•Tritordeum sourdough bread had firmer and more defined texture than baker's yeast bread.
In this study, technological role of α-glucan with (α1-3) and (α1-6) glycosidic linkages produced by Lactobacillus reuteri E81 on sourdough rheology and bread texture was investigated. To achieve ...this, a glucan deficient ΔgtfA mutant was produced by the deletion of the glucansucrase gene from strain E81. By comparison of glucan-positive and glucan-negative strains for rheological properties of sourdough revealed that in situ α-glucan production resulted in higher elasticity in sourdough. However, no additional effect of in situ glucan on textural characteristics of bread was observed although addition of glucan ex situ at 0.09% level significantly decreased bread hardness. Scanning Electron Microscopy (SEM) images of lyophilized sourdoughs confirmed association of glucan and starch granules forming a film like structure in sourdough.
•Sourdoughs with Lactobacillus reuteri E81 and ΔgtfA mutant possessed different acidity.•SEM images confirmed the glucan-starch association in sourdough.•In situ glucan formation resulted in higher viscosity in sourdough.•Bread texture was not affected by in situ glucan production but ex situ addition positively affected the bread texture.
Sourdough has been used in bread production for decades to improve its preservation, texture and flavor. Today it is mostly used as a bread flavor improver. For many years, bread volatile compounds ...have been referenced and more than 540 have now been reported. In contrast, sourdough volatile compounds have been less studied. No listing of these compounds has been previously carried out and their origins have not been reported in a review.
The scope of this review is to detail the volatile compounds previously reported in sourdough and sourdough bread in order to highlight the most common ones. Methods for studying volatiles in sourdough and sourdough bread are first listed. Then the volatile compounds identified from previous papers about sourdough aroma are characterized to understand their origins and their contribution to bread aroma.
According to this review, the main extraction technique applied to sourdough and sourdough bread is headspace solid-phase micro-extraction. To date, 196 volatile compounds have been reported in sourdough and sourdough bread including 43 aldehydes, 35 alcohols, 33 esters, 19 ketones, 14 acids, 13 furans, 11 pyrazines, 2 lactones, 2 sulfurs, 21 others and alkanes. The most recent characteristics of most of these volatile compounds (origins, odors and odor thresholds) are reported as well as their presence in sourdough, sourdough bread or bread. This report underlines the production levers that could modify sourdough and bread aroma.
•Comparison of volatile compounds extraction methods used on sourdough and bread.•540 volatile compounds previously reported in sourdoughs and in sourdough breads are listed.•Origins, odor quality and threshold and presence in sourdough and bread of most of the volatile compounds are reported.
Impact of sourdough on the texture of bread Arendt, E.K; Ryan, L.A.M; Dal Bello, F
Food microbiology,
04/2007, Letnik:
24, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
Sourdough has been used since ancient times and its ability to improve the quality and increase the shelf-life of bread has been widely described. During sourdough fermentation, lactic acid bacteria ...(LAB) produce a number of metabolites which have been shown to have a positive effect on the texture and staling of bread, e.g. organic acids, exopolysaccharides (EPS) and/or enzymes. EPS produced by LAB have the potential to replace more expensive hydrocolloids used as bread improvers. Organic acids affect the protein and starch fractions of flour. Additionally, the drop in pH associated with acid production causes an increase in the proteases and amylases activity of the flour, thus leading to a reduction in staling. While improving the textural qualities of bread, sourdough fermentation also results in increased mineral bioavailability and reduced phytate content. In this review we will be discussing the effect of sourdough on wheat and rye bread as well as the potential of sourdough to improve the quality of gluten-free bread.
This study investigated the effects of foxtail millet sourdough fermentation time (0, 8, 16, and 24 h) on the protein structural properties, thermomechanical, fermentation, dynamic rheological, ...starch granules crystalline regions molecular mobility, and starch microstructural characteristics. The fermentation led to a significant increase in the concentration of free amino acids from protein hydrolysis. Fourier transform infrared spectroscopy (FTIR) revealed changes in protein secondary structure and the presence of functional groups of different bioactive compounds. The result of thermomechanical properties showed a significant increase in the stability (0.70–0.79 min) and anti-retrogradation ability (2.29–3.14 Nm) of lactic acid bacteria (LAB) sourdough compared to the control dough, showing a wider processing applicability with radar profiler index. In contrast, sourdoughs with lower tan δ values had higher elasticity and strength. Scanning electron microscopy showed that the surface of the starch appeared from smooth to uneven with patchy shapes and cavities, which declined the crystallinity from 34.00 % to 21.57 %, 23.64 %, 25.09 %, and 26.34 % respectively. Fermentation changed the To, Tp, Tc, and ΔH of the starch. The results of the study will have great potential for application in the whole grain sourdough industry.
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•Whole grain foxtail millet sourdough was fermented by four strains of LAB.•LAB fermentation improved dough rheological and thermomechanical characterization.•LAB fermentation affected starch crystal structure and protein structure.
•Lactobacillus sanfranciscensis and Lactobacillus pontis were dominant bacteria.•The dominant fungal species were Kazachstania humilis and Saccharomyces cerevisiae.•A stable microbial consortia was ...established in sponge dough and main dough.•Extended sponge retarding led to abundant volatile compounds with much more esters.•Accumulation of organic acids and ethanol contributed to formation of ethyl esters.
Dynamics of microbial community and changes of metabolites during production of type Ι sourdough steamed bread made by retarded sponge-dough method (SSB) were studied. Lactobacillus sanfranciscensis and Lactobacillus pontis were the dominant bacterial species. Particularly, relative abundances of Lactobacillus sanfranciscensis were significantly higher than that of other sub-dominant bacterial species. The dominant fungal species were Saccharomyces cerevisiae and Kazachstania humilis, and the latter was the most predominant. A stable bacterial and fungal consortia was established in sponge dough retarded from 12 to 24 h and main dough proofed from 30 to 60 min. Metabolism preference for maltose of Lactobacillus sanfranciscensis favoured a mutualistic association with maltose-negative Kazachstania humilis, and hence contributing to their competitiveness and dominance. Volatile compounds became more abundant with much more esters as sponge retarding time extended. Probably, the accumulation of organic acids and ethanol contributed mostly to formation of ethyl esters in sponge dough during retarding.
The fermentation of type I sourdough was studied for 20 d with daily back‐slopping under laboratory and artisan bakery conditions using 1 wholemeal and 2 refined soft wheat (Triticum aestivum) ...flours. The sourdough bacterial and yeast diversity and dynamics were investigated by plate counting and a combination of culture‐dependent and culture‐independent PCR‐DGGE approach. The pH, total titrable acidity, and concentration of key organic acids (phytic, lactic, and acetic) were measured. Three flours differed for both chemical and rheological properties. A microbial succession was observed, with the atypical sourdough species detected at day 0 (i.e. Lactococcus lactis and Leuconostoc holzapfelii/citreum group for bacteria and Candida silvae and Wickerhamomyces anomalus for yeasts) being progressively replaced by taxa more adapted to the sourdough ecosystem (Lactobacillus brevis, Lactobacillus alimentarius/paralimentarius, Saccharomyces cerevisiae). In mature sourdoughs, a notably different species composition was observed. As sourdoughs propagated with the same flour at laboratory and artisan bakery level were compared, the influence of both the substrate and the propagation environment on microbial diversity was assumed.
Practical Applications
Bakery foods made from wholemeal flours have many health benefits, mainly due to their high content of bran fiber. However, wholemeal flours are poorly utilized in breadmaking due to their low leavening ability and richness in antinutrients (phytates). The use of wholemeal sourdoughs might represent an alternative to baker's yeast for future development of more nutritious cereal‐based foods.
In this study, spray-dried and freeze-dried sourdough powders were produced and characterized. In addition, the powder samples were used to produce sourdough breads. Differences observed in powder ...properties of sourdough powders (particle surface morphology, bulk density and flowability) depending on the method used. The powder samples were used at four blending ratios (3, 6, 9 and 15%) to assess the effect of their use on physico-chemical properties of sourdough breads produced. Converting sourdough into powder preserved the viability of both lactic acid bacteria and yeasts at certain numbers (final counts for both LAB and yeast were around 5 cfu/g and 8 cfu/g for freeze-dried powder and spray-dried powder, respectively). Satisfactory results were obtained with both spray dried and freeze dried sourdough powders even though there were significant changes in some dough properties and reduction of volume of bread products when powder starters used in comparison with control samples (p < 0.05). Therefore, the results obtained in this study suggest that freeze-dried and spray-dried sourdough powders could be used as alternatives to fresh sourdoughs in dough formulations.
•Sourdough powders were produced using spray-drying and freeze-drying.•Powder flow and particle morphology of sourdough powders were investigated.•Sourdough powders contained acceptable number of viable LAB and yeast cells.•Sourdough powder improved the shelf life of bread samples.
Due to a large adaptability to different cultivation conditions and limited input compared to other cereals, sorghum is considered an emerging crop. Its antioxidant properties, high fiber content and ...low glycemic index also make it a valuable addition to a healthy diet, nevertheless, the presence of antinutritional factors and the lack of gluten, hamper its use as food ingredient. This study investigated the impact of sourdough fermentation on sorghum nutritional quality. Lactic acid bacteria dominating sorghum flour and sourdough were identified by culture-dependent analysis revealing Lactiplantibacillus plantarum as the dominant species found in the mature sourdough, whereas Weissella cibaria and Weissella paramesenteroides were the species isolated the most after the first refreshment. Among yeasts, Saccharomyces cerevisiae was the most prevalent. Lactic acid bacteria pro-technological and functional performances as starter were evaluated in sorghum type-II sourdoughs through an integrated characterization combining chromatographic and NMR spectroscopic techniques. The metabolic profile of the strains mainly grouped together W. cibaria strains and W. paramesenteroides AI7 which distinguished for the intense proteolysis but also for the presence of compounds particularly interesting from a physiological perspective (allantoin, glutathione, γ-aminobutyric acid and 2-hydroxy-3-methylbutyric acid), whose concentration increased during fermentation in a species or strain specific matter.
•Lactic acid bacteria and yeasts were isolated from sorghum flour and sourdough.•Lactiplantibacillus plantarum was dominant in the mature sourdough.•LAB pro-technological and functional performances were evaluated.•Metabolome was investigated through chromatographic and NMR techniques.•W. cibaria and W. paramesenteroides strains caused an intense proteolysis.
